Dissertations / Theses: 'New Zealand ecology'

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Burrell, Gregory P. "Hyporheic ecology of alluvial rivers in Canterbury, New Zealand." Thesis, University of Canterbury. Zoology, 2001. http://hdl.handle.net/10092/4805.

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Aspects of the ecology of hyporheic river communities in Canterbury, New Zealand were examined using field surveys in association with field and laboratory experiments. Seasonal pump-sampling of Ashley River tributaries revealed an invertebrate fauna dominated numerically by harpacticoid copepods, although insects (particularly Chironomidae and Polycentropodidae) dominated biomass. Dissolved oxygen (minimum concentration = 2.1 mg 1-1) was negatively related to invertebrate abundance in reaches receiving upwelling groundwater in summer, but not winter. Thus, seasonal limitation of dissolved oxygen may occur in river reaches where upwelling is prevalent. Colonisation pots embedded in the Waipara River collected a high proportion of epigean taxa, notably the snail Potamopyrgus antipodarum, whereas pump-samples were biased towards collecting non-insect taxa, including harpacticoids and mites. In colonisation pots, the hyporheic biota (15-45 cm depth) represented about 50% of total (0-45 cm) invertebrate abundance and community respiration. Willow leaves added to colonisation pot gravels increased invertebrate abundance and community respiration, but their effect declined with depth. Low concentrations of silt (<2.5 g per litre of sediment) appeared to enhance the food resource for some collector-filtering taxa (particularly oligochaetes and ostracods), whilst lessening its value to the grazers P. antipodarum and Hydora sp. (Elmidae). The epilithic microbial community found in the hyporheic zone was similar to that of heavily-shaded surface epilithon, and both had lower biomass and a less diverse microbiota (algae and fungi) than epilithon grown in full light. While the epigean caddisfly 0. Feredayi ingested hyporheic foods, it did not grow in the absence of either higher quality light-grown epilithon, or particulate organic matter. Fine sediment (<2 mm diameter) added to colonisation pot gravels (up to 23% of total sediment dry weight) reduced invertebrate abundance and community respiration (CR) at all depths (0-45 cm). However, invertebrate community composition was influenced more strongly by fine sediment at depths below 15 cm, indicating that conventional stream sampling may provide an inadequate measure of sediment effects on the benthos. Finally, my data indicate that the hyporheic zone is likely to be sensitive to human activities. Therefore, water managers need to consider the biota of surface and subsurface waters concomitantly, so that freshwater ecosystems can be understood, maintained and protected, effectively.

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Collier, Kevin J. "Ecology of acid brownwater streams in Westland, New Zealand." Thesis, University of Canterbury. Zoology, 1988. http://hdl.handle.net/10092/4809.

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Effects of water chemistry and catchment afforestation on benthic invertebrates were investigated in acid brownwater and circumneutral clearwater streams in Westland, South Island, New Zealand. Annual dissolved organic carbon (DOC) budgets calculated for three North Westland wetland catchments (zero, two and five years post-afforestation) showed that forestry development resulted in a reduction of DOC export by up to 24 % and that recovery of DOC dynamics was linked to the time elapsed since the onset of development. The presence of high DOC concentrations in stream water (up to 41 g.m-3) resulted in lowering of pH to about 4.0. These highly acidic waters also contained high concentrations of dissolved aluminium, but only a small proportion (< 80 mg.m -3) was in the toxic labile (inorganic) monomeric form.

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Poupart, Timothée. "Foraging ecology of winter-breeding seabirds in New Zealand." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS016.

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Bien que le coût énergétique de la reproduction contraigne les animaux à élever leur(s) jeune(s) pendant le pic d’abondance de ressource alimentaire au printemps et/ou en été, certaines espèces font exception en se reproduisant en hiver. Comment leurs besoins énergétiques élevés peuvent-ils être satisfaits pendant une période traditionnellement décrite par des conditions environnementales difficiles réduisant les ressources alimentaires ? Cette question a été peu étudiée jusqu’à présent. Cette stratégie originale de reproduction hivernale est adoptée par davantage d’espèces d’oiseaux marins en Nouvelle-Zélande qu’ailleurs dans le monde, avec une concentration sur la côte ouest de l’île du Sud. Dans ce contexte, cette thèse a eu trois objectifs. Tout d’abord, décrire le comportement de recherche alimentaire à fine échelle d’espèces d’oiseaux marins nicheuses en hiver clés du réseau trophique, sur la côte ouest de l’ile du Sud de la Nouvelle-Zélande. Ensuite, examiner les facteurs intrinsèques et extrinsèques déterminant leur comportement. Enfin, quantifier le recouvrement de leurs niches écologiques sur leur zone d’alimentation durant la période d’élevage du(des) jeune(s). Nous avons étudié la stratégie de recherche alimentaire sur une communauté d’espèces constituée de deux guildes : les oiseaux plongeurs (manchot du Fiordland Eudyptes pachyrhynchus) et de surface (pétrel de Westland Procellaria westlandica, albatros de Buller Thalassarche bulleri bulleri). L’approche s’est basée sur le déploiement de bio-loggers sur ces oiseaux (GPS, accéléromètre, enregistreur de plongée) et l’analyse isotopique (carbone, azote) de sang prélevé après leur voyage en mer. Les individus équipés se sont moins éloignés de leur colonie que leurs espèces congénères nichant en été, en utilisant majoritairement les eaux du talus continental et néritiques. Mâles et femelles ont eu des comportements de recherche alimentaire semblables, avec des différences spatiales concernant l’albatros de Buller. Des taux de rencontre de proies élevés ont été enregistrés chez les trois espèces, permettant un élevage du(des) jeune(s) avec un taux de succès élevé, et sans effort supérieur par rapport aux espèces nichant en été. Ces résultats suggèrent que les oiseaux marins nichant en hiver sur l’île du Sud de la Nouvelle-Zélande ont une phénologie de reproduction concordant avec des ressources alimentaires hivernales locales suffisantes. Des données supplémentaires issues de la littérature ont permis d’inclure le manchot bleu Eudyptula minor et le Cormoran tacheté Stictocarbo punctatus (espèces nichant aussi en hiver sur la même côte) dans l’étude de ségrégation de niche écologique. Cette communauté a montré un recoupement partiel de leur niche écologique, mais aussi un faisceau de divergences sur le plan des déplacements horizontaux, verticaux, de la distribution temporelle de l’activité de recherche alimentaire, du régime alimentaire et de la niche isotopique. Cette ségrégation écologique explique la coexistence de cette communauté avienne dans un même habitat. Par conséquent, la stratégie de reproduction hivernale peut être favorable aux oiseaux marins prédateurs supérieurs, lorsque des processus océanographiques locaux sont favorables. Sur le plan océanographique, un mélange vertical des eaux attire et garantit la persistance de proies au cours de l’hiver. En outre, la phénologie hivernale de la reproduction contribue aussi à l’émancipation du poussin au printemps. Ainsi, elle concorde avec le pic local de productivité primaire, en accord avec les prédictions. Ces espèces présentes en populations modestes, peuvent ainsi terminer leur cycle de reproduction hivernal avant que d’autres espèces beaucoup plus abondantes (comme les millions de Puffin fuligineux Puffinus griseus) rentrent de migration et s’engagent à leur tour dans leur reproduction estivale
Although the cost of reproduction constrains animals to breed during spring/summer when food availability peaks, exception exist in seabirds with few species engaged in breeding during winter months. How their elevated energy needs can be sustained during a period traditionally reported for food shortage and challenging at-sea conditions is poorly understood. In addition, this unusual breeding phenology is adopted by more species in New Zealand than elsewhere in the world, with a concentration on the South island west coast where several winter breeding species are reported to forage with overlap. Therefore, the objectives of this thesis were to: 1) describe the fine-scale foraging behaviour of winter-breeding species from the west coast of New Zealand’s South Island, 2) investigate the intrinsic and extrinsic factors driving their foraging, and 3) quantify their niche overlap as they exploit similar areas during elevated energetically demand. Using bio-logging data (GPS, accelerometer, dive recorder) combined with stable isotopes (carbon and nitrogen from whole blood), the winter foraging strategies of breeding males and females were investigated in a deep diver (Fiordland penguin Eudyptes pachyrhynchus) and two surface-feeders / shallow divers (Westland petrel Procellaria westlandica and southern Buller’s albatross Thalassarche b. bulleri). The tracked individuals foraged close to their colony compared to their summer breeding congenerics, using primarily the nearby shelf-slope and neritic waters. Males and females displayed similar foraging behaviour in penguins and petrels, while spatial sexual differences occurred for albatross. All three species encountered prey at a high rate, allowing raising offspring with good success and without higher foraging effort than their summer-breeding congeners.These findings suggest that winter-breeding species have a phenology matching a winter prey resource on the shelf of the west coast of New Zealand’s South Island. With additional data from literature for little penguin Eudyptula minor and spotted shag Stictocarbo punctatus, this winter-breeding community showed partial overlap of their foraging niche, but an accumulation of small divergences in home ranges, diving behaviour, temporal pattern of foraging, diet and trophic level is likely to explain their coexistence. Hence, winter-breeding can be a favourable phenology for high-level predators, which exploit shelf-slope and inshore waters undergoing winter mixing that insure fish and squids persistence through winter. In addition, winter-breeding also allow the matching of chick-fledging period with the spring (local primary production peak), and before the elevated needs of millions of summer-breeding species back from migration

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Cipriano, Frank Walter. "Behavior and occurrence patterns, feeding ecology, and life history of dusky dolphins (Lagenorhynchus obscurus) off Kaikoura, New Zealand." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186097.

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My dissertation research focused on the behavior, movement patterns, and foraging ecology of dusky dolphins (Lagenorhynchus obscurus) off the east coast of New Zealand's South Island. Information on growth, morphometrics, parasites and life history was also collected. Movement patterns and foraging behavior of New Zealand dusky dolphins were much different from those of dusky dolphins observed off the Argentine coast by Bernd Wursig, the only other study of dusky dolphin behavior. Unlike the Argentine dolphins, which cooperatively herd anchovy to the surface and contain them there for feeding, New Zealand dusky dolphins behave and forage more like Hawaiian spinner dolphins (Stenella longirostris). In summer and fall, New Zealand dusky dolphins remain near shore in morning and early afternoon hours, then move into deeper water with greatly increased activity levels in late afternoon. In winter and spring they remain farther from shore at all times of day, are found in somewhat larger groups, and appear to travel along shore more often than in other seasons. In summer, dive times of radio-tagged dolphins also varied on a daily cycle, most long dives occurring during crepuscular and night periods. Stomach contents of incidentally-netted and beachcast dolphins contained primarily a demersal fish and a few types of mesopelagic fishes and squid. Acoustic surveys along the east coast of South Island show a dense layer of mesopelagic fishes and squid that move to within 50-100 m of the surface at night. Like Hawaiian spinners, New Zealand dusky dolphins feed primarily on prey in and associated with the vertically migrating layer, probably as a means of increasing foraging efficiency. External measurements of L. obscurus specimens were analyzed using canonical variate analysis, which revealed measurements useful in discrimination of age/sex classes, including dorsal fin dimensions, and positioning of dorsal fin and flipper insertions. Tooth-section age analysis of specimens allowed construction of growth curves; life span maximum was about 35 years. The very large size of active testes (over 1 kg each) during summer breeding represents a large proportion of total body weight. Along with observations of group composition variability, this suggests a promiscuous mating system and a fluid, extended-group social system.

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Ebbett, R. L. "The ecology of lowland totara in South Island, New Zealand." Thesis, University of Canterbury. Forestry, 1998. http://hdl.handle.net/10092/4833.

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Historically, lowland totara was a common forest tree throughout much of lowland New Zealand but is now confined to small, mainly protected, areas usually as the dominant species in mixed podocarp forest with matai and kahikatea. Lowland podocarp forest has suffered the most extensive reduction of all New Zealand forest types, with only circa 1% of the original forest cover remaining. The lowland totara dominated stands remaining therefore represent an highly fragmented population with relatively few individuals, making the collection of large data sets difficult. Sample sizes are small in some stands due to the limited area of to tara dominated forest (circa 1 hectare). The present study aims to describe the natural extent of lowland totara forest, document its reduction and current status, and to provide for the long-term survival of this species in the now fragmented forest environment. Literature relating to the ecology of Podocarpus totara is reviewed with respect to vegetative morphology and growth, reproductive biology, timber properties and· utilisation, and population dynamics. The ecological niche of lowland totara is defined, examining site characteristics and soil type. The distribution of lowland totara dominated stands is a function of several interlinked site characteristics such as climate, landform, drainage, disturbance regime, soil type, and altitude. Lowland totara appears to be confined to semi-fertile or fertile soils which are the result of landform and disturbance e.g. flood events on a river plain. Stand descriptions identify lowland totara forest as ranging from pure totara, to totara - matai, to totara - matai - kahikatea, to dense mixedpodocarps. The relative proportions of totara, matai, and kahikatea appear to be due to edaphic features such as fertility and drainage. In dense mixed podocarp forest, totara is confined in small populations to optimal sites such as terraces and ridges. The podocarps have differing nutrient, light, and disturbance regime requirements and these factors work together to partition the environment into optimal areas for the regeneration and persistence of each species. Totara dominated stands require high light to initiate and capture a high fertility site, and relatively free-draining ABSTRACT 3 fertile soils to remain dominant. Sub-optimal totara sites will see the dominance of other species such as rimu. Totara and kahlkatea dominate in catastrophically disturbed areas, miro responds to medium levels of disturbance such as tree fall, and rimu dominates in areas subject to continual disturbance such as canopy collapse. Regeneration of lowland totara dominated forest is seen to be a consequence of seedling dispersal to preferred microsites, and disturbance history. The broad scale forest pattern is detennined by the level of disturbance and the finer scale pattern of tree distribution is a result of light levels, parent and perch trees, and edaphic properties. There is no evidence that totara dominated stands are older than first generation, indicating that periodic catastrophic regeneration is required to reinitiate stands. The alteration of the natural disturbance regime by humans may pose problems for the future of lowland totara. There is no evidence that totara forest regenerates under a senescing totara canopy. Presently protected areas are therefore likely to undergo floristic composition change away from totara/matai/kahlkatea in the absence of disturbance. A landscape management plan is proposed as a mechanism for appropriate land use using ecological principles at catchment scale and to provide adequate areas for the long-term survival of totara dominated forest in a fragmented landscape. New Zealand's natural environment has been radically altered with the invasion of humans, introduced weeds and pests, and alteration of the natural disturbance regime. Restoration and revegetation are therefore options for the future survival of lowland totara in a fragmented landscape. Silvicultural plantations can provide timber (to tara heartwood being highly prized), income, and seed sources for regeneration. Land values such as water and soil quality will also benefit from artificial plantations. Stand spacing and age structure is described and can be used in the future when revegetation projects have the aim of approximating natural stands.

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Redd, Sarah M. "Effects of varying environments on the ecology and evolution of the New Zealand Mud Snail and its interactors." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/s_redd_100109.pdf.

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Thesis (M.S. in zoology)--Washington State University, December 2009.
Title from PDF title page (viewed on Jan. 21, 2010). "Department of School of Biological Sciences." Includes bibliographical references (p. 34-40).

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Poorbagher, Hadi, and n/a. "Life-history ecology of two New Zealand echinoderms with planktotrophic larvae." University of Otago. Department of Marine Science, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081029.160011.

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The importance of parental nutritional status on planktotrophic larvae was investigated in both laboratory-conditioned and field (populations) parents of two New Zealand echinoderms: the sea urchin Pseudechinus huttoni and the starfish Sclerasterias mollis. Three questions were addressed: (i) Does parental nutritional status affect the reproductive features (gonad index, gametogenesis, fecundity and biochemical composition) both in the laboratory and under natural conditions? (ii) Does parental nutritional status affect egg characteristics (diameter, number, dry weight, fertilization rate and biochemical composition)? (iii) Are the characteristics of larvae (growth, development, morphology, mortality rate and body composition) influenced by parental or larval nutrition (or both)? To answer the first question, adult P. huttoni and S. mollis were maintained in the laboratory with a low or high diet (in terms of quantity and quality for P. huttoni, and in terms of quantity for S. mollis) for one year. The effect of low and high diets on reproductive features was studied and the same parameters were studied in two parental populations with dissimilar food availability (for P. huttoni: Otago Shelf and Doubtful Sound populations; for S. mollis: Otago inshore and offshore populations). To address the second question, egg characteristics of the laboratory-held and field parents were measured. The third question was answered by rearing larvae of the laboratory and field parents with both low and high concentration planktonic diets. P. huttoni reared in the laboratory with a higher food ration had greater gonad indices and lipid concentration and larger oocyte area. Sea urchins from the Doubtful Sound population had higher food availability, greater gonad lipid concentration and larger oocytes. Parental nutrition had some effect on the characteristics of the egg in P. huttoni. The laboratory-held urchins fed a high diet produced larger eggs: P. huttoni from Doubtful Sound produced larger eggs with a greater carbohydrate concentration. P. huttoni larvae from low-fed laboratory and Otago Shelf parents had faster development The effect of larval nutrition was more important than parental food availability on larval growth and development. Feeding parents in the laboratory had no effect on larval morphology but larvae from Doubtful Sound, which had better food availability, had longer arms relative to body width. A higher cell concentration in the planktonic diet led to shorter larval arm relative to body width. In S. mollis reared in the laboratory, a higher food ration led to larger gonad and pyloric caeca indices. The starfish from an Otago inshore population mainly had a higher gonad index than those from an Otago offshore population. In the laboratory-held parents S. mollis, nutrition had no effect on the egg characteristics. In the field, starfish with higher food availability produced smaller eggs with lower carbohydrate concentration. There was no significant difference between development rates of S. mollis larvae from low and high fed laboratory parents. However, those from the Otago inshore parents, with better food availability, had faster development than the larvae from Otago offshore parents. In S. mollis larvae, the origin of the parents (either from the laboratory or the field) had no effect on larval shape. A higher concentration planktonic diet led to longer larvae relative to body width in larvae from high-fed laboratory parents. In both P. huttoni and S. mollis, parental and larval diet had no effect on rate of instantaneous larval mortality. In both P. huttoni and S. mollis larvae, biochemical composition of the larvae and the egg were different to each other. Egg reserves appear not to be a factor which affects larval characteristics in these species.

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Fraser, Elizabeth Anne. "Population Ecology of Thelymitra matthewsii Cheeseman Orchidaceae, in Northern New Zealand." The University of Waikato, 2008. http://hdl.handle.net/10289/2291.

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The terrestrial orchid Thelymitra matthewsii Cheeseman, uncommon in New Zealand, was studied to increase knowledge of the species life cycle, morphology and ecology. Results will enhance future conservation management for the species. New information related to the morphology of T. matthewsii was obtained. The species was found to emerge in one of four discrete life stages of distinctive morphology and height range that remained constant for the season, not developing into a more advanced life stage. The leaf of the three pre adult life stages designated a hook, a spiral, and a non flowering stage, did not inflate at the base, but rose smoothly from the tuber. Apparent morphological differences in the column between descriptions of the Australian taxon and the small New Zealand sample examined suggested further study was needed. Comprehensive monthly monitoring was carried out at five study sites in three locations in the Te Paki area of the Far North, from 2002 to 2004. No patterns emerged in plant life stage succession, flowering, and presence or absence at labels reinforcing the concept that variability was a common component of the population census. Seasonal and partial absence was a major component of the populations. An average of 32.8% of plants, over five study sites, were present throughout three seasons, while 66.9% were recorded as absent (not visible) at monitoring. New plants appearing in 2003 and 2004 showed a high percentage of subsequent absence (mean 85.7%). To determine population stability, recruitment and absence were compared. Plant absence exceeded recruitment by 7% (mean plant absence 30.5%; mean recruitment 23.4%). Plants continued to appear during the monitoring period, and labeled plants increased two-fold over commencement numbers. Adults recorded as 28% of labeled plants over three seasons, were out numbered by pre-flowering stages. Only 5% of population numbers exhibited succession from a smaller to a flowering plant. Life stage modeling indicated a life stage was more likely to be followed by the same stage than an expected successive stage. Thelymitra matthewsii was found to be present in four substrates in the Far North. The survey of vegetation found the indigenous species Kunzea ericoides and the exotic Hakea gibbosa dominant for both height, and cover. Litter and bare ground dominated ground cover. Differences in vegetation and ground cover, of sites supporting T. matthewsii and comparison sites that did not, were minor and suggested that another factor, for example a suitable fungal partner, influenced the species presence or absence. The results of the study indicated the present threat classification of Thelymitra matthewsii is inadequate in the light of the species relatively circumscribed, widely separated habitats, the small number of reproducing individuals and vulnerability to habitat modification.

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Markowitz, Timothy Michael. "Social organization of the New Zealand dusky dolphin." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/537.

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Social organization of dolphins in extensive societies has not been well studied. Off Kaikoura, New Zealand, thousands of dusky dolphins (Lagenorhynchus obscurus) gather, feeding nocturnally on deep scattering layer prey, resting and socializing diurnally. During 1997-2003, interval sampling was used to monitor large assemblages numbering hundreds (n=169), smaller mating groups (mean+s.e.=7+1.6 adults, n=42), mother-calf nurseries (mean+s.e.=13+1.6 adults, 1+0.5 juveniles, 4+0.7 calves and 1+0.4 neonates, n=41), and non-mating adult groups (mean+s.e.= 9+1.3 adults, 1+0.2 juvenile, n=37). Group size, distance from shore (east), ranging along shore (north), traveling, inter-individual distance, and noisy leaping peaked in winter (n=39), with dolphins maintaining closer proximity to each other in smaller, more restful groups, closer to shore during the spring-summer-autumn (n=234) reproductive seasons. Dolphin groups were found closest to shore (west) during early morning, spread out and leaping often. Resting peaked at midday in tight groups. Late in the day, dolphins spread out, moving eastward (offshore) in preparation for feeding. Large groups exhibited coordinated travel, with noisy leaps as a directional signal. "Mating of the quickest" occurred in groups of (median) 6 males chasing 1 female. Leaping rarely occurred in restful nurseries, which at times associated with Hector's dolphins (Cephalorhynchus hectori). Other mixed-species groups included common dolphins (Delphinus delphis), southern right whale dolphins (Lissodelphis peronii), long-finned pilot whales (Globicephala malaena), and bottlenose dolphins (Tursiops truncatus). Killer whales (Orcinus orca) elicited predator assessment and evasion. Whale riding occurred with larger whales. Residence was seasonal, with 1,969+814.9 from a population of 12,626 dolphins spending 103+38.0 days in Kaikoura (mean+s.e., mark-recapture mortality, single-season lagged-ID emigration models, n=153 weeks). Dolphins (n=39) summering in Kaikoura migrated to the Marlborough Sounds in winter, where small, coordinated groups foraged diurnally on schooling fishes in shallow bays, often associated with sea birds and New Zealand fur seals (Arctocephalus forsteri). Aquaculture may threaten dusky dolphin foraging habitat in Admiralty Bay, where an estimated 220 dolphins gathered to feed each winter. Photo-identification research, enhanced by digital techniques, demonstrated a structured fission-fusion society. Dusky dolphins associated with preferred long-term (>1,000 days) hunting companions in Admiralty Bay and non-random casual acquaintances (200 days) in Kaikoura (lagged-association models).

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Sutherland, Darin Lee. "Phylogeography and Ecology of New Zealand Freshwater Amphipoda (Paracalliope, Paraleptamphopus, and Phreatogammarus)." The University of Waikato, 2006. http://hdl.handle.net/10289/2650.

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ABSTRACT This thesis examines phylogenetic patterns in three New Zealand amphipod taxa in relation to current geographic distributions and historical climatic (e.g. glaciation, marine inundation) and geological (e.g. mountain building) events using DNA sequencing and distributional data. It also examines how recognition behaviour can be used to delineate potential species boundaries and to assess the role of sexual selection. The endemic genus Phreatogammarus has been found in only a limited number of sites and is not very abundant. An analysis of the genetic variation of two species within the genus using allozyme electrophoresis revealed high levels of genetic differentiation among populations but low levels within populations. This suggested that limited dispersal occurred among habitats with one population possibly representing a cryptic species. The endemic freshwater genus Paraleptamphopus is thought to contain a large number of undescribed species with a number of these existing in small waterbodies such as seepages. Examination of the phylogeographic patterns using both mtDNA (CO1) and nuclear DNA (28S) showed that a number of distinct genetic lineages exist, with CO1 revealing 21 haplotypes with genetic distance of over 20%. Using a molecular clock rate of 2.4%, most haplotypes diverged approximately 8-12 million years ago during the Miocene era, possibly as a result of greater land availability increasing habitat diversity or by allopatric speciation. Morphological and genetic differences were not congruent, with morphologically similar taxa appearing among highly genetically distinct lineages, and some morphologically distinct forms appearing within single lineages. The distribution and habitat variables of 419 sites were analysed to determine what was affecting the presence or absence of Paraleptamphopus. The presence of native vegetation in catchments had a positive affect on Paraleptamphopus distribution suggesting that large anthropogenic changes in catchment vegetation could have a negative effect on their abundance. I found smaller waterbodies to be more important than larger ones highlighting the need to study such sites as rare taxa may be ignored. A better understanding is needed on the role of small waterbodies in promoting overall species diversity in catchments. Examination of Paracalliope fluviatilis phylogenetic patterns using the mtDNA gene CO1 showed that a number of separate clades existed suggesting long term isolation and limited dispersal among catchments. Due to the large genetic divergences among some populations there was the possibility that cryptic species might exist. Species recognition experiments were conducted on seven populations to help determine whether cryptic species were present. For the three most genetically divergent crosses there was bias against inter-population pairings, suggesting that there were between two or three separate species. Using a combined field and laboratory approach, size assortative mating was examined in Paracalliope fluviatilis. The field study showed positive size assortative mating and that larger females carried more eggs, suggesting they were more fecund. A series of laboratory experiments examining four existing theories explaining the phenomenon found that none adequately explained positive size assortative mating in P. fluviatilis. I therefore presented two new explanations to explain size assortative mating: a combination of female resistance and size-related variation in a male's capacity to amplex larger females or a form of indirect intra-sexual competition.

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Lord, Janice M. "The evolutionary ecology of Festuca Novae-Zelandiae in Mid-Canterbury, New Zealand." Thesis, University of Canterbury. Botany, 1992. http://hdl.handle.net/10092/4900.

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Festuca novae-zelandiae (Hack.) Cockayne is a long-lived, caesptiose grass indigenous to New Zealand. It has expanded dramatically in range in 1000 years of human settlement. This study was conducted to determine how generalist life-history attributes and 'adaptive' variation have enabled this species to adjust to environmental change. A range of aspects of the biology of F. novae-zelandiae were investigated. Reproduction in 155 individuals over four seasons was monitored. Only 17.4% of individuals flowered every year and 36.1 % did not flower at all. However, the reproductive output of the population was still relatively consistent between years. Reproduction of individuals and the pre-dispersal fate of seeds was compared among eight sites. Differences existed among sites for most attributes measured. Site factors appeared to mask any effects of tussock density on culm production. Total seed predation was positively related to density and negatively to altitude. A flightless fly, Diplotoxa moorei (Diptera, Chloropidae) was found to be the most common identifiable seed predator, accounting for up to 8% of seeds produced in some populations. Seed germination was compared for eight populations in laboratory trials and most seeds germinated easily. Mean final % germination across all populations was 86%. Seedlings were monitored in the field for 30 months. They commonly established on mat-vegetation, were very slow-growing (mean of 0.6 leaves yr-1) and had a half-life of 12 months. Tillers in 26 tussocks were tagged and monitored for 30 months. Tillering was concentrated in spring, tillers lived on average 15.2 months and the majority (64%) did not produce daughter tillers. Tillering rate was not affected by either position within a tussock or size of the tussock. A stage-based approach was used to investigate population structure. Stages were defined using discriminant analysis. The discriminant function was then used to assign stages to 255 tussocks which had been measured at the beginning and end of a two year period. Transition probabilities were calculated between stages. Transitions were distinctly non-linear and tussock size and condition could vary widely in the space of two years in response to environmental fluctuations. The genetic identity of mapped tussocks was investigated using isozyme electrophoresis and it was found that clonal fragmentation did not contribute significantly to the maintenance of population densities. Patterns of variation at different taxonomic levels were compared using three taxa: F. novae-zelandiae s.s., a distinct high altitude form of F. novae-zelandiae and a closely related species, F. matthewsii. Vegetation composition was investigated using ordination and classification techniques. Environmental gradients in altitude, temperature and rainfall were important in explaining observed patterns. The vegetation composition at "high altitude" F. novae-zelandiae sites was more distinct from that of F. novae-zelandiae s.s. sites than the latter was from F. matthewsii sites. Morphological variation in the same taxa was investigated using Principal Components Analysis. The same environmental factors were important to observed patterns of variation. Populations within F. novae-zelandiae possessed some genetically-determined differentiation that related to habitat. A narrow zone of intermediacy was found between F. novae-zelandiae s.s. and F. matthewsii. Plants from populations of the three taxa were grown in cultivation. Culms of F. matthewsii emerged four weeks prior to F. novae-zelandiae s.s. "High altitude" F. novae-zelandiae was more similar to F. matthewsii in flowering phenology. Levels of biochemical variation in populations of all three taxa were investigated using isozyme electrophoresis. All populations were characterised by high within-population variation and relatively low between-population variation. The differences between the three taxa were small. Variation among populations related to environmental factors but not to the proximity of populations. The adaptiveness of populations to their own environment was tested using reciprocal transplants. No 'home-site' advantage was found. All populations proved to be highly plastic in growth responses. The findings of this study are discussed in terms of generalist versus specialist strategies in long-lived, polyploid, perennial grasses. I conclude that in environments characterised by unpredictable, short-term fluctuations, long-lived species will show adaptation to large-scale, long-term environmental trends only, and adopt a generalist strategy in the face of short-term fluctuations.

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12

Leduc, Daniel, and n/a. "The ecology and taxonomy of meiofauna at Papanui Inlet, with particular emphasis on nematodes." University of Otago. Department of Marine Science, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081124.143019.

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Meiofauna are an ecologically significant component of marine benthic communities worldwide. Nematodes, in particular, are arguably the most abundant metazoans on Earth and often form highly diverse communities in marine sediments. The study of meiofauna, however, often lags behind that of macrofauna, probably due to the small size of meiofaunal organisms and the paucity of suitably-trained taxonomists or para-taxonomists. Our understanding of basic ecological questions, such as the role of meiofauna in the energetics of benthic communities, as well as the nature and extent of possible relationships between meiofauna and macrofauna in detritus-based communities, is still limited. The present study aimed to address these questions in the context of intertidal seagrass (Zostera muelleri) meadows and adjoining unvegetated sediments in Papanui Inlet, Otago Peninsula. The near absence of taxonomical and ecological studies on free-living marine nematode species in New Zealand also prompted the description of several new species and as well as a comparison of species assemblages from the study sites. Meiofaunal abundance (range: 1325-4979 ind. 10cm�) in the top 5cm of sediments was not significantly different inside and outside the seagrass meadow. Meiofaunal biomass and production estimates were small relative to macrofauna (approx. 1 and 5% of macrofaunal values, respectively), with little variation in both meiofaunal and macrofaunal values between vegetated and unvegetated habitats. Analysis of the isotopic and fatty acid composition of primary producers, sediment organic matter, and consumers at the study sites suggest that a significant proportion of secondary productivity in seagrass meadows is fuelled by macrophyte detritus. These data suggest that secondary productivity in the seagrass meadow was limited by the low palatability of macrophyte detritus compared with microalgal food sources, resulting in lower trophic transfer efficiency in vegetated sediments. These results contrast with previous findings showing a large contribution of meiofauna to the secondary productivity of vegetated sediments, as well as greater secondary productivity inside than outside seagrass meadows. The nature of the sediments (coarse particle size with low organic matter content) is likely to have led to low meiofauna biomass whilst favouring large suspension feeders. The low availability of high quality food sources (i.e. seston, benthic microalgae, and epiphytes) in vegetated sediments may have contributed to the lower than expected secondary productivity inside the seagrass meadow. Most of the dominant nematode species found at the study sites were new to science, and 6 new species were described. Significant differences were found in the nematode assemblages between sites and sediment depths. There was a trend of greater nematode diversity and abundance in vegetated sediments, but this was restricted to the uppermost 2cm of sediments. The effect of seagrass on nematode assemblages is likely to be mediated by the effect of blades on sediment characteristics and the presence of roots. The present study suggests that the presence of Zostera muelleri results in greater biodiversity of sheltered soft-shore communities on a local scale. The addition of ��C-labelled macroalgal detritus (Enteromorpha) to microcosms in a feeding experiment resulted in minimal labelling of harpacticoid copepods and nematodes. Lack of change in the fatty acid composition of the latter also suggests limited assimilation of detritus during the experiment. It is likely that consumers choose benthic microalgae over detritus when both food sources are available in the field. High content of highly unsaturated fatty acids (HUFAs) in nematodes from the field suggests, for the first time, that they are a high quality food source to higher trophic levels. A feeding experiment investigating the effect of bacterivorous nematodes on detritus assimilation rates by amphipods did not support the hypothesis that nematodes increase the trophic transfer efficiency between detritus and macrofaunal detritivores. It is unclear whether amphipods preferentially fed on detritus or whether nematodes escaped predation by burrowing deeper in the sediment. Data obtained in the present study, however, shows that marine bacterivorous nematodes can biosynthesise/accumulate HUFAs in high concentrations despite their low concentrations in their diet. Nematodes could, therefore, provide an important source of these essential nutrients to bulk deposit feeders living in otherwise HUFA-poor sediments.

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13

Wiseman, Nicky. "Genetic identity and ecology of Bryde's whales in the Hauraki Gulf, New Zealand." Thesis, University of Auckland, 2008. http://hdl.handle.net/2292/2612.

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Little long-term research has been conducted in the Hauraki Gulf on Bryde’s whales; the least studied baleen whale. This thesis investigates this population using photoidentification and sighting records obtained from boat-based opportunistic surveys and genetic analyses of samples from living and `stranded’ whales. Samples from `stranded’ Bryde’s whales have been collected since 1994 from the North Island of New Zealand. In addition, biopsy samples were collected from whales in the Hauraki Gulf. Fifty-two samples from `stranded’ and biopsied Bryde’s whales identified 49 unique individuals using 12 polymorphic microsatellites. The sex ratio for both sample collection types were equal with 22 males : 23 females (the sex of four could not be determined). MtDNA D-loop analysis (~800 bp) identified the samples as being consistent with Balaenoptera brydei with 11 haplotypes defined by 16 variable sites. Comparisons with published sequences (373 bp) revealed three shared haplotypes between the North Pacific and Indian Oceans. However, an AMOVA (FST and ΦST) showed high levels of differentiation between these oceans, likely resulting from ancestral gene flow. Between March 2001 and February 2006, 1,102 boat-based surveys were conducted during which there were 1,059 sightings over 521 days of Bryde’s whales (including two birth-length calves) in the Gulf. Since whales with calves, were observed during all months this suggests that the Hauraki Gulf is an important area for breeding whales. The seasonal change in `trip encounter rate’ indicated that some whales leave the Gulf for part of the year. Whales in the Gulf were observed in shallower (12.1 to 59.8 m) and cooler (12 to 24.5oC) water than has generally been reported elsewhere. Balaenoptera brydei corresponds to the form described in the offshore waters of the western North Pacific. In contrast, their habitat use in the Hauraki Gulf was more consistent with the `inshore’ form from the coasts off South Africa.
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14

Miller, Craig J. "Conservation ecology of riparian forest within the agricultural landscape: West Coast, New Zealand." Thesis, University of Canterbury. Forestry, 2002. http://hdl.handle.net/10092/4801.

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This study seeks to determine the spatial extent and characteristics of riparian forest on the South Island's West Coast, and to examine the ecological status and condition of riparian forest patches within the West Coast's agricultural landscape. The majority of West Coast riparian forest occurs on south Westland floodplains. Further north these forests were found to comprise <20% of the vegetation cover in 16/27 of the region's Ecological Districts. Today >80 000 ha (53%) of the floodplains are in pasture, and <1% of the farmed areas are in indigenous forest. Remaining forests on the farmed floodplains are comprised of many small patches (mean size 3.7 ± 0.3 ha), with only 13 patches  9 ha.

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15

Schweikert, Katja, and n/a. "The functional biology of Porphyra sp. in New Zealand." University of Otago. Department of Botany, 2007. http://adt.otago.ac.nz./public/adt-NZDU20080910.114121.

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The intertidal red algal genus Porphyra is found on rocky shores worldwide. In the Northern Hemisphere the genus is well studied but there is a paucity of data on southern hemisphere Porphyra and even less on New Zealand Porphyra. The species� taxonomy has been undergoing revision since the late 1990�s, when it was discovered that the main species P. columbina and P. lilliputana reported for New Zealand were a combination of several endemic species. These species are found from the low to the high intertidal watermark; hence they are exposed to fluctuating stresses such as desiccation, temperature, high light and UV radiation. Algae have evolved a number of mechanisms to adapt to naturally changing increasing abiotic conditions, such as accumulation of screening pigments and changes in antioxidant metabolism during light stress. For terrestrial plants, polyamines (small aliphatic amines) have been shown to be involved in protecting cells from damage under conditions of stress including UV-B radiation; such mechanisms have yet to be identified in algae. The overall aim of this study was to determine the importance of cellular processes in shaping the community structure of Porphyra on a wave-exposed shore on the east coast of the South Island, New Zealand. Porphyra distribution and community structure was assessed by regular monthly monitoring of presence and absence of Porphyra along four transect lines at the site. Enviromnental information was recorded to determine the effects of temperature, light, UV radiation, humidity and wind on Porphyra�s spatial and temporal distribution. Regular tissue samples were taken for species identification by the application of primers, which were specifically designed during this study. P. cinnamomea and Porphyra spec. "ROS 54" were identified as dominant species present almost throughout the year with a pronounced maximum in presence during late winter and spring, and some weeks of absence during April or May. The two dominant species were recorded from the low to the high intertidal shore, but the mid intertidal was identified as the preferred habitat. Other species that were found were rare and only present for a few months in a very restricted area. It was hypothesised that free radical generation and antioxidant metabolism are associated with desiccation tolerance in Porphyra. An attempt was made to investigate the impact of desiccation stress on Porphyra. The extraction process of antioxidants was problematic and no reproducible results could be obtained. It was attempted to investigate the spatial distribution of spores and conchocelis of different Porphyra species in the field, and determine if those found at Brighton Beach are species-specific in their morphology. This indicated that the two main Porphyra species at Brighton Beach not only prefer to occupy the same habitat but that they also have a morphologically similar conchocelis phase. Mechanisms on a cellular level such as polyamine metabolism affected by environmental (abiotic) stresses are related to the alga�s ability to adapt to stress and therefore can have an effect on Porphyra�s distribution along the shore and its presence throughout the year. The depletion of the ozone layer has become an important issue as the effects of increased UV radiation on the environment, especially the intertidal habitat, are revealed. Marine macrophytes possess the main three. polyamines: putrescine, spermidine and spermine of varying levels. For the few species studied, Rhodophyta generally contain higher levels of polyamines than Chlorophyta, while polyamine levels for the one heterokontophyte analysed were between Chlorophyta and Rhodophyta. Levels of the three most common polyamines (putrescine, spermidine, spermine) were determined in P. cinnamomea under controlled UV exposure. Tissue discs were exposed to visible light (PAR), PAR and UV-A or PAR, UV-A and UV-B radiation. Discs exposed to PAR and PAR and UV-A showed little change in polyamine levels over a six day trial period, while discs exposed to PAR, UV-A and UV-B showed a significant increase in free, bound soluble and bound insoluble polyamines over the same period of time. Correspondingly levels of ADC and ODC, two enzymes involved in polyamine synthesis, were measured. ODC levels changed little while ADC levels increased significantly during UV-B treatment, indicating that under UV-B stress polyamines are mainly synthesized via the ADC pathway. The experimental set-up and process of this study has not been applied in macroalgal polyamine research and results obtained are the first indication that increased levels of polyamines are involved in protection and/or protection mechanisms in macrophytic algae to prevent UV-B damage.

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16

Scott, Matthew B., and n/a. "Fine-scale ecology of alpine patterned ground, Old Man Range, Central Otago, New Zealand." University of Otago. Department of Botany, 2007. http://adt.otago.ac.nz./public/adt-NZDU20080130.093120.

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This study is an interdisciplinary ecological study addressing the fine-scale relationships between plants, invertebrates and the environment in an alpine ecosystem. Alpine environments are marked by steep environmental gradients and complex habitat mosaics at various spatial scales. Regular forming periglacial patterned ground landforms on the Old Man Range, Central Otago, South Island, New Zealand present an ideal medium for studying plant-invertebrate-environment relationships due to their partitioning of the landscape into discrete units of contrasting environmental conditions, and the existence of some baseline knowledge of the soil, microclimate, vegetation and flora. The study was conducted in three types of patterned ground (hummocks, stripes and solifluction terraces) on the Old Man Range. Each component of the study was sampled at the same spatial scale for comparison. Temperature was recorded in the soil and ground surface from April 2001 to March 2004 in microtopographic subunits (microsites) of each patterned ground landform. Plant species cover was sampled within each microsite; invertebrates were sampled from soil cores taken from the same locations as plant samples in April 2001 and September 2001. The two sampling occasions coincided with autumn before the soil freezes, and winter when maximum freezing was expected. Fine-scale changes in the topographic relief of the patterned ground led to notable differences in the timing and duration of snow. The steepest environmental gradients existed during periods of uneven snow distribution. The soil in exposed or south-facing microsites froze first, beginning in May, and typically froze to more than 40cm depth. Least exposed microsites rarely froze. Within the microtopography, patterns of freezing at specific locations were consistent between years with only minor differences in the timing or depths of freezing; however, notable variation in freezing existed between similar microsites. Within the microtopography, different assemblages of organisms were associated with different microsites. In total, 84 plant and lichen species were recorded, grouping into six community types. Species composition was best explained by growing degree-days, freeze-thaw cycles, time frozen and snow-free days; species diversity and richness increased with increasing environmental stress as indicated by freeze-thaw cycles, time frozen and exposure. In total 20,494 invertebrates, representing four Phyla, 12 Classes, 23 Orders and 295 morpho-taxa were collected from 0.17m� of soil. Acari, Collembola and Pseudococcidae were the most abundant invertebrates. Over 95% of the invertebrates were found in the plant material and first 10cm depth of soil. Few significant relationships were found between diversity, richness or abundance of invertebrate taxa and the microsites; however, multivariate analyses identified distinct invertebrate assemblages based on abundance. Invertebrate composition was best explained by recent low temperature and moisture, particularly in winter; however, plant composition also explained invertebrate composition, but more so in autumn. This research has shown that organisms in the alpine environment of the Old Man Range are sensitive to fine-scale changes in their environment. These results have implications as to how historical changes to the ecosystem may have had long-lasting influences on the biota, as well as how a currently changing climate may have further impacts on the composition and distribution of organisms.

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17

Harbrow, Michael Andrew. "Ecology of streams affected by acid mine drainage near Westport, South Island, New Zealand." Thesis, University of Canterbury. School of Biological Sciences, 2001. http://hdl.handle.net/10092/2126.

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Macroinvertebrate assemblages, physico-chemical factors, epilithic algal biomass and leaf decomposition were examined in streams draining the Charming Creek and Stockton-Millerton coalfields north of Westport, South Island. Three invertebrate community types were evident in the streams depending on the degree of contamination by acid mine drainage. A diverse (9-31 taxa) "clean water" fauna dominated by the mayfly Deleatidium, larval Elmidae and various Trichoptera and Tipulidae occurred down to pH 4.5 where iron concentration was < 0.69 mg l⁻¹ and aluminium < 0.41 mg l⁻¹. At sites subject to moderate acid mine drainage and iron hydroxide precipitation, diversity was lower (9-13 taxa) and invertebrate density was often very low. Spaniocercoides phi/potti, a Zelandobius species and Oxyethira albiceps dominated. In the most polluted streams, where pH < 3, conductivity> 300-450 µS cm⁻¹ and metal concentrations were elevated (Fe> 5.7 mgl⁻¹, Al > 3.4 mg l⁻¹ ) taxonomic diversity was very low (2-6 taxa) but invertebrate abundance was often very high. Chironomidae made up 80-100% ofindividuals caught. Acid streams were dominated by habitat generalists rather than specialist acidophiles. Biomass ofperiphytic algae examined experimentally in 7 streams (pH 2.8-6.2) was greatest at low pH. It appeared to be affected by precipitation of iron hydroxide, nutrient concentration and the absence ofbicarbonate below pH 5.5. Grazing by invertebrates did not appear to have a significant effect on algal biomass. Decomposition ofbeech (Nothofagus) and kamahi (Weinmannia) leaves in 6 acidic-eircumneutral streams lacking shredders was slow, and differences in decomposition rates in the contrasting streams were evident only after 6 months. As in other parts of the world, acid mine drainage has a severe effect on New Zealand stream ecology.

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Creswell, Paul D. "Feeding ecology of the New Zealand Cancer crab Cancer novaezelandiae (Jacquinot, 1853) (Brachyura: Cancridae)." Thesis, University of Canterbury. Department of Zoology, 1988. http://hdl.handle.net/10092/2419.

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This study investigates the predatory behaviour of Cancer novaezelandiae (Decapoda : Brachyura : Cancridae), a subtidal crab from Lyttelton Harbour, Banks Peninsula. Cancer crabs were obtained at bimonthly intervals over a 22 month sampling period. Examination of stomach contents suggested that C.novaezelandiae was an opportunistic predator feeding on a wide variety of food items. Molluscs composed the major components of diet, with bivalves and gastropods comprising 35 % of all food items. Crustacea were the next most important group comprising 20 % of all food items. Amphipods, isopods and crabs were the most frequent crustaceans found. Other food types included fish, sponges, coelenterates and plant matter in relatively low abundances. No variation in dietary composition was evident with crab sex, size or season. The functional morphology of the chelae, mouthparts and gastric mill were examined for two size-classes of crab (60.0-70.0 and 120.0-130.0 mm carapace width). The mouthparts and gastric mill were generalised in structure and were typical of large, predatory brachyurans. Large crista dentata of the third maxilliped and sharp, rounded mandibles, together with large, heavily chitinised gastric mill ossicles suggested that C.novaezelandiae was well equipped to macerate course, particulate matter. No variation in either mouthparts and gastric mill structure was evident with crab size or sex. Left and right chela of C.novaezelandiae were morphologically similar in shape and dental pattern, and no difference was found between sexes. Relative growth of the chelae was described from measurements made on propodus height and length using carapace width as the reference dimension. Log-transformed regressions were used to test for allometric growth and lines were compared using t-tests. No significant difference was found in the growth of the propodus between left and right chelipeds, and for males and females. Relative growth of the propodus was positively allometric which remained constant throughout crab growth. No discontinuity in growth of the propodus was evident for male and female crabs (however for male crabs over 110 mm carapace width there was a slight indication of increased propodus growth). Both left and right chela of male and female crabs had a large diastema, and mean mechanical advantage of 0.367 and 0.375 respectively. The high mechanical advantage of the chela in C.novaezelandiae appeared to remain constant throughout crab growth, allowing a compressive force in excess of 496 kN.m⁻². The polyfunctional chela are therefore, capable of holding, manipulating and crushing a variety of prey shapes. Predator-prey experiments were undertaken in the laboratory using male crabs of three size classes (55.0-65.0, 80.0-90.0 and 105.0-115.0 mm carapace width). Prey used included blue mussel Mvtilus edulis aoteanus, cockle Chione stutchburyi, spotted whelk Cominella maculosa and catseye Turbo smaragdus. C.novaezelandiae adopted five distinct techniques to open bivalve and three techniques to open gastropod shells. The particular opening technique used was influenced by crab size, prey size and success of previous attempts. Small molluscs were usually opened by direct crushing by the chela and/or mouthparts. Splitting of the umbone valves and removal of the aperture lip were the most successful techniques used to open large bivalves and gastropods respectively. Handling times increased exponentially with prey size, with large crabs requiring less time to open prey than small crabs. Prey species influenced handling times with bivalves opened more quickly than gastropods. Critical maximum prey size increased with crab size, while minimum critical size was smaller for small crabs. Different sized crabs consumed similar numbers of prey, but energy intake increased with crab size. Profitability curves were derived and tested with regard to optimal prey size and species. When presented with a size range, crabs selected prey sizes that minimized time spent foraging. However when presented with different prey species, crabs maximized energy intake by selecting optimum prey species. Findings suggested C.novaezelandiae exhibited a flexible foraging behaviour, which allows crabs to maximize feeding efficiency. This was discussed in the context of the ecology of the crab and the Energy Maximization Premise (Elner and Hughes, 1978).

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19

Davis, Joanna Margaret. "The demography and ecology of the pulmonate limpet Siphonaria zelandica at Kaikoura, New Zealand." Thesis, University of Canterbury. Biological Sciences, 1996. http://hdl.handle.net/10092/3449.

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Siphonaria zelandica is a common intertidal pulmonate limpet in New Zealand. On the Kaikoura Peninsula, east coast of the South Island, S.zelandica is abundant on rocky platforms in damp crevices. This study examines the demography and ecology of S.zelandica at two sites on the peninsula. The distribution and abundance was examined both spatially and temporally. S.zelandica are found primarily in the mid tidal area with an average of 90limpets/m² over all sites although abundance does vary between sites. S.zelandica are, however, not strongly associated with any other gastropod species, although they are correlated with algae. Two size measurement methods were used to ascertain growth and mortality of S.zelandica, and the reproductive cycle was also determined. Growth is variable over time, being quicker in winter and spring than in summer/autumn. Growth is also variable with initial size of the animal with smaller size classes (5-10mm) growing rapidly and the larger size classes having slower growth. Mortality is greater in the larger S.zelandica than in small size classes and is affected by physical disturbances such as storms. Reproduction in S.zelandica is continuous over the year as shown by histological slides which showed that there were mature oocytes present throughout the year. There are peaks in spawning however that occur in February/March (late summer) and September/October (early spring) which indicate main spawning phases. Hatching after the eggs had been laid took between six and ten days and settlement was fairly rapid after this. The grazing effect of S.zelandica on algal abundance and the effects of differing densities of limpets on intraspecific survival and growth were examined through experimental enclosures. 0.25m² enclosures were constructed and randomly assigned treatments at two sites. The different densities used were 0,15, 30 and 50 limpets which represent half ambient, ambient and double ambient densities and the experiment was run for twelve months. It was found that although S.zelandica had some effect on algal abundance at differing densities, overall they cannot reduce micro or macroalgae by significant levels. An increase in density of the limpets had no effect on S.zelandica survival. Growth was significantly different between sites although there was no significant treatment effect. Experimental enclosures were also used to examine whelk predation on S.zelandica. Treatments used were a series of total and half cages with 30 S.zelandica and either with or without whelks. The treatments were duplicated at both mid and low shore. The experiment had a two-fold nature, it indicated the level of whelk predation at different shore heights and the survival of S.zelandica at the different shore heights. Whelks consume reasonable numbers of limpets at both mid and low shore heights but predation is increased at the low shore. S.zelandica does not survive well at the low shore regardless of being protected from whelks. Oystercatcher predation was examined by observations of foraging flocks. These found that oystercatchers have a major effect on limpet populations leaving, on average, only 10% of S.zelandica untouched in a patch after the birds foraging session. The behaviour of the oystercatchers was unusual as they turned the limpets over but never actually consumed them. The main conclusions of this study are that S.zelandica contribute to the patch dynamics of the Kaikoura shore by having both direct and indirect effects. The direct effects of S.zelandica are the localised population effects on algal abundance. Indirectly, S.zelandica are prey for both birds and whelks, which is a factor in their patchy distribution that in turn creates space for other organisms to settle.

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Gruner, Ingrid Gerda. "Comparative Ecology and Conservation of Rare Native Broom, Carmichaelia (Fabaceae), South Island, New Zealand." Thesis, University of Canterbury. School of Forestry, 2003. http://hdl.handle.net/10092/4152.

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Using a comparative approach, the presented study explores the ecology of ten species of native New Zealand broom, Carmichaelia, and their vulnerability to competition and herbivory, with the aim of gaining a better understanding of the significance of introduced species as a threat to rare indigenous plants in New Zealand. In particular, the study focuses on the relationship between characteristics of the Carmichaelia species and their vulnerability, as well as on other factors influencing the significance of introduced species as a threat. To gain a better understanding of the ecology of the Carmichaelia species, their current habitats and associated plant communities were investigated using quantitative-descriptive methods in the field. The effect of competition with introduced plants was studied in two glasshouse experiments, differentiating above ground competition for light from below ground competition for nutrients and water. The experiments focussed on the early life-stage of seedling establishment of the Carmichaelia species. The impact of herbivory by introduced mammals was studied in four field-based exclosure trials, focussing on the effects on survival and reproductive activity of adult Carmichaelia plants. The results showed that the effects of competition and herbivory vary between the different species. Furthermore, they provided a set of species characteristics that can be used as indicators to predict the vulnerability of Carmichaelia to the impact of introduced species. These indicators provide a useful tool for threatened species management, as they allow the identification of the most vulnerable species as well as the most significant threat to each species. Furthermore, the indicators can be used to group species, combining those with similar vulnerability profiles, and therefore, likely similar management needs. However, the example of the Carmichaelia species also illustrated that the use of indicators for the vulnerability of threatened species is limited and needs to be combined with case-by-case studies to verify the actual significance of threats for each population of concern. The vulnerability profiles derived from species’ characteristics can be used to guide such site specific studies, ensuring they focus on the most relevant threat factors. This combination of the understanding of general patterns in the vulnerability of species with targeted species and site-specific studies will lead to increased efficiency in the conservation management of threatened plant species.

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21

Morley, Craig Gordon. "The ecology and behaviour of feral ferrets (Mustela furo) in Canterbury farmland, New Zealand." Thesis, University of Canterbury. Zoology, 1999. http://hdl.handle.net/10092/5824.

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Ferret (Mustela furo) control programs, especially those attempting to prevent the spread of Mycobacterium bovis (Tb), would greatly benefit from practical knowledge of ferret ecology and behaviour. This study had two main objectives: firstly, to investigate ferret ecology by examining ferret abundance, survival, trapping success, and diet; and, secondly, to investigate ferret behaviour and activity patterns by using an acoustically sensitive transmitter system (ASTS). Abundance and survival estimates of ferrets tagged with passive integrated transponders (PITs), showed a marked seasonal variation, and despite ferrets being controlled on one site, data from both sites showed that lagomorph numbers increased exponentially. A trapping success model (GLIM) showed that factors such as vegetation cover, rabbit sign, and animal tracks positively influenced capture rates. Although GPS technology provided accurate trap location data, trapping success also benefited from understanding the distribution signs of both predators and prey. GPS data further contributed to GIS models of animal movements, home range and site fidelity. As a result, trapping success was found to be affected by periods of low ferret abundance, fluctuations in trappability and possibly excess prey. It was found that, even though cats and ferrets use different hunting strategies, lagomorphs were their staple prey in North Canterbury. Unlike overseas habitats, New Zealand farmland lacks alternative suitable prey and this may explain the narrow diet of both predators. Even with the large increase in lagomorph numbers seen in North Canterbury in the second year of study, the diets of both predators remained the same, suggesting that these predators are unable to regulate lagomorphs once their numbers cross a certain threshold. By using ASTS technology to examine ferret behaviour and activity it was possible to identify a wider range of behaviours than previously documented using conventional radio tracking techniques. Despite using only one ferret, it was not only possible to document the time of an activity period, the length of each behaviour, as well as seasonal changes in activity, but also behaviours rarely recorded by researchers using more conventional techniques. Generally the ferret displayed an ultradian activity pattern, disputing the accepted nocturnal hypothesis. One implication for ferret control programs using baited traps was a documented decrease in eating behaviour during the breeding seasons. Nevertheless, this study provided as many questions as it did answers; however, with technology such as ASTS, further information about the behaviour and ecology of ferrets could advance future ferret control programs.

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22

Novis, P. M. "Ecology and taxonomy of alpine algae, Mt. Philistine, Arthur's Pass National Park, New Zealand." Thesis, University of Canterbury. Plant and Microbial Sciences, 2001. http://hdl.handle.net/10092/6977.

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At least 67 distinct algal taxa occur in the alpine basins of Mt Philistine, Arthur's Pass National Park This flora differs from others reported in alpine and polar regions. Nine species of snow algae were found, none of which appear to grow in other habitats, and at least 6 of which are new records for New Zealand. An abundance of other algae are present, including cf. Gloeocapsa, Cyanothece aeruginosa, Fischerella sp., and Myrmecia cf. irreguiaris, which are particularly widely distributed throughout different habitats on the site. Certain other taxa are common in selected habitats, such as cf. Ammatoidea in some pools and Chlainomonas kolii in snow on the surface of an alpine tarn. Distinct assemblages of algae occur in snow and associated with the moss Andreaea mutabilis. Assemblages in pools, soils, mineral fines, on rock surfaces, and associated with vascular plants are not distinguishable, which may reflect the shortcomings of using presence/absence data as the basis for ordinations. The complete life-cycle of the enigmatic C. kolii is still not understood. This alga has previously been found only in snow beneath forest in North America, where it is generally exposed to much lower light intensity and higher nutrient levels than in alpine New Zealand. However, C. kolii on Mt Philistine grows during prolonged rainstorms, when liquid water content increases, light intensity decreases and freezing at night is absent. Timing of the bloom each year appears to be related to the amount of snow deposited during the previous winter. Snow algae resting cysts are deposited by retreating snow onto underlying substrata on the site. However, their ultimate fate is unknown. Many algae are lofted and dispersed elsewhere, including onto snow from other habitats. An unidentified snow algal cyst (possibly Chlamydomonas sp.) is a small component of the aerobiota. C. kolii has not been found in these samples. The cyanophytes Fischerella sp. and cf. Gloeocapsa dominate the aerobiota. Collection of air-borne algae illustrates the problem of distinguishing wind-deposited propagules from active algae in a given habitat, especially those organisms requiring cultures for their detection and identification. Temporal variation of cultured organisms from aerobiota suggests that their growth periods are distinct from many of those absent from cultures. This is a further factor reducing the resolution of ordination techniques for analysis of distribution patterns.

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23

Buchanan, Samuel J. "Spat production of the Greenshell™ mussel Perna canaliculus in New Zealand." Thesis, University of Auckland, 1999. http://hdl.handle.net/2292/1707.

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The research presented in this thesis was undertaken in order to develop an understanding of the biology of Perna canaliculus sufficient to allow for commercial hatchery based production of Greenshell™ mussel spat. Hatchery production is an alternative to unreliable and inconsistent wild spat collection. In a Perna canaliculus population followed for one year spawning occurred in early spring and late summer. Three quantitative histological measures of gonad maturity utilising image analysis technology and a qualitative classification system were compared. Measuring the relative surface area comprised of gametes on histological sections was found to be the most reliable method. A practical gonad visual index to determine the reproductive condition of adults for the selection of broodstock was developed and found to be highly effective as a means of predicting induced spawning success. Serotonin was not effective for inducing spawning of Perna canaliculus. Temperature shock and the use of stripped gametes was however found to be a reliable spawning induction method. Relative gamete concentration, gamete age, temperature, sperm half life and gamete contact times were all found to have effects on fertilisation success for Perna canaliculus. Sperm concentration and the conditions of sperm aging were particularly important. Fertilisation kinetics of Perna canaliculus gametes modelled using the Vogel-Czihak-Chang-Wolf method suggested that 5% of sperm-egg contacts lead to successful fertilisation. Broodstock management protocols that could be used to condition the adult of Perna canaliculus were investigated in order to enhance and prolong the natural reproductive season. Research suggested that for successful broodstock conditioning animals should already have begun gametogenesis at the time conditioning is commenced. Successful conditioning of Perna canaliculus was achieved at temperatures between l0 and 16°C over a period of about 50 days. A diet ration above 2-3% of the dry meat mass per day is suggested. A trial examining non-algal diet supplements suggest a mixture of yeast and lipid emulsion may have some potential value. Photoperiod manipulation did not effect the reproductive condition of Perna canaliculus. The yield of veliger larvae was significantly enhanced if embryo culture water was treated with 1.0 mg/l EDTA. Veliger yield was not significantly affected at densities below 50 embryos/ml. Perna canaliculus larvae grew most rapidly and survived well at the salinity of 35 ppt. Larvae grew most rapidly when cultured at low densities. Experiments suggest that early larvae can be cultured at 5-10/ml, however late stage larvae grew most rapidly when cultured at l/ml. Perna canaliculus larvae displayed best growth and good survival if fed a mixed flagellate-diatom diet comprising Isochrysis galbana (T-Iso) and Chaetoceros calcitrans. The optimal diet ration, as a function of larval size, increased from about 20 cells/μl Isochrysis galbana (T-Iso) to around 150 cells/μl through the larval development period. Thyroxine between the concentrations of l0-5 and l0-8 M did not have an observable effect on larval developmental rate or eye spot development. Down welling settlement systems were found to be generally successful for Perna canaliculus lanrae. L-DOPA was also demonstrated to enhance the settlement and metamorphosis of Perna canaliculus pediveligers.

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24

McClellan, Rachel Katherine, and n/a. "The ecology and management of Southland's black-billed gulls." University of Otago. Department of Zoology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090827.110233.

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The black-billed gull (Larus bulleri) is a small gull that nests in dense colonies on gravel-bedded rivers in southern New Zealand. This dissertation describes research undertaken in Southland in 2004-2006 that investigates black-billed gull population decline and its causes. Historical ground counts of nests were calibrated with aerial photography of colonies and population trends analysed. The decline in breeding birds on Southland's four main rivers was equivalent to 6.0%/year (SE 1.8) or 83.6% in 30 years justifying the species' present listing as Endangered. Aerial monitoring is a poor index of the breeding population and major temporal variation was identified in counts. All re-sighted second-year birds exhibited natal dispersal and -70% left the natal catchment. Forty one percent of birds banded as adults also dispersed to other catchments. Breeding dispersal is apparently unrelated to previous breeding success and the availability of the previous year's colony site, and dispersing birds did not move as groups. Southland's black-billed gulls constitute a single inter-mixing population. Black-billed gulls selected sites on islands and banks according to availability, and selected rivers consistent with the number of gravel patches. Site vulnerability to floods varied significantly. Re-use of colony sites was positively influenced by use in previous years, the extraction of gravel, site stability and low weed cover. Widespread introduced weeds on colony sites preventing nesting and may have increased flooding risk. Colony size was related to colony area, which was related to gravel patch size. Investigation of historical changes in breeding habitat availability in Southland indicated a major reduction in gravel habitat on the Lower Oreti River between 1976 and 2002 due to river works including gravel extraction. On the Waiau River, Manapouri Dam construction in 1970 initially increased gravel areas, since reversed in the mid Waiau, and caused a 75% decline in the number of islands. Gravel patch sizes are still declining on the Lower Oreti and possibly the Mid Waiau. Hundreds of gravel patches remain on Southland rivers. Over 5000 nests in 21 colonies were monitored during incubation. Colony nest success was most influenced by colony location, averaging 90.1% (SE 2.1) on islands within rivers, and 66.8% (SE 2.2) on riverbanks, indicating that terrestrial predators exert the greatest influence on productivity. Breeding success, the mean number of fledglings produced per nest by colony, varied between 0 and 0.88 fledglings (mean 0.32, SE 0.08). Both parameters were positively related to colony size. The three smallest colonies failed to breed successfully, suggesting the presence of an Allee effect. Deterministic matrix models were used to investigate population trends using survival and productivity estimates for the closely related Kaikoura red-billed gull (L. novaehollandiae scopulinus). Adult survival, followed by breeding success and survival of first year birds, had the greatest influence on population projections. Improvements in most parameters are probably required to reverse the decline of Southland's black-billed gulls. Predation and disturbance by introduced mammals and the native black-backed gull (L. dominicanus) had the greatest impact on black-billed gull productivity. Most human disturbance is insignificant compared to predator disturbance, but illegal shooting of large numbers of adult gulls has major impacts in smaller sub-populations. Damming and excessive water abstraction reduces island habitat due to lowering of flows. Major climatic events such as droughts, and chemical ingestion through a diet dominated by agricultural invertebrates, are potential major threats about which little is known. Management actions including the collation and analysis of all unpublished black-billed gull count datasets, a thorough test of the accuracy of aerial monitoring, trialling of decoys to attract colonies to nest on islands, predator control at bank colonies, targeted weed control on high quality sites, advocacy and education and further research are recommended.

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Sinton, Amber. "The ecology of freshwater communities of stock water races on the Canterbury Plains." Thesis, University of Canterbury. School of Biological Sciences, 2008. http://hdl.handle.net/10092/2273.

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Agricultural intensification on the Canterbury Plains in New Zealand has lead to the degradation of natural streams and rivers through lowering of water quality and significant reduction of surface flows from the use of ground and surface water resources. However, this same agricultural expansion has led to the development of a network of permanently flowing open water races to supply stock water to farms across the Canterbury Plains. Stock water races form an extensive network, with approximately 6,500 km of races. Initially I surveyed 62 water races and compared habitat characteristics, water quality, benthic invertebrate and fish communities with nearby natural streams. Races are characterised physically by straight, narrow and shallow channels, and small, uniform substrate. Water races are more turbid than natural streams, and can have high summer temperatures. The benthic macroinvertebrate communities of water races contained a range of taxa, including some not found in natural streams, but communities were less diverse than communities in natural streams, and tended to be dominated by a limited set of generalist taxa. A longitudinal study of three water races showed gradients in physical characteristics of races, including a downstream decrease in channel width, water depth, current velocity and substrate size. However, few strong longitudinal changes to community structure were found, as the generalist taxa commonly occurring in water races were able to tolerate conditions throughout the race network. To test if macroinvertebrate communities were limited by the homogeneous habitat of water races, I conducted a substrate manipulation experiment, where large cobbles and small boulders were added to reaches in five water races. Despite an increase in substrate and current heterogeneity, there were few significant changes to the macroinvertebrate communities over the four months of the manipulation. This outcome does not eliminate low habitat heterogeneity as a limiting factor for water race communities. Rather, the benthic invertebrate community throughout the water race network is a product of the homogeneous habitat, which limits the availability of colonists of taxa that would benefit from increased habitat diversity. A survey of the fish assemblages of water races found races had a depauperate fish community. Only two species were commonly found in water races, and the average species richness of races was 1.5. By contrast natural streams had a higher diversity of fish species (mean 4 three species), and contained representatives of a greater number of species that are typical of streams and rivers on the Canterbury Plains. My research has shown that stock water races provide an important source of aquatic biodiversity on the plains, both in addition to natural streams and in their own right. However, the biodiversity value of stock water races could be improved with enhancement of in-stream habitat.

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26

Jardine-Coom, Laura. "When men and mountains meet : Rūiamoko, western science and political ecology in Aotearoa/New Zealand." Thesis, University of Canterbury. Geography, 2010. http://hdl.handle.net/10092/3821.

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On the 13th of March, 2007 a failure of the tephra dam at Te-wai-a-moe, the Crater Lake of Mt Ruapehu in the North Island of Aotearoa/New Zealand, caused a lahar to travel down the Whangaehu River channel. The lahar event had been predicted after an eruptive event at Mt Ruapehu eleven years before. As a result of the early prediction, the lahar event and potential risk was well studied, and twenty four management options were proposed to mitigate risk. After a period of consultation with stakeholders, including local iwi, the Minister for Conservation ratified a non-intervention option which emphasised monitoring and prohibited engineering intervention on the mountain. The media event associated with 2007 lahar event drew considerable attention to the 1953 Tangiwai tragedy which occurred following a similar lahar event at Mt Ruapehu. The 2007 lahar media event constructed Tangiwai as a site of risk that belonged to science, technology and Pakeha tragedy, dominating understandings of Tangiwai as an important spiritual place for local iwi and their relationship with Mt Ruapehu. The lahar event also highlighted the dominant western science based hazard management paradigm and its interactions with matauranga Maori. Inherent in the dominant western science paradigm is the natural/social split born of the scientific Enlightenment and the removal of non-humans as actors. Bruno Latour (2004) calls for a move beyond the natural/social dualism and recognition for the importance of non-humans in contesting and recreating worlds; this thesis considers Charles Royal’s tangata whenua paradigm as an answer to Latour’s call.

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27

Brown, Stephen Nicholas. "Ecology and enhancement of the flat oyster Ostrea chilensis (Philippi, 1845) in central New Zealand." Thesis, University of Canterbury. Biological Sciences, 2011. http://hdl.handle.net/10092/6203.

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Human activities are causing a global loss of plant and animal species, degrading ecosystem properties and threatening ecosystem services. One indicator of these losses is the increasing proportion of fish stocks in decline, and the Challenger oyster fishery in Tasman Bay, central New Zealand is an example of one such fishery. Anthropogenic effects from land-based activities, and towed-gear fishing have been implicated as contributors to the decline of shellfisheries and degradation of the marine ecosystem in Tasman Bay. Increased sedimentation in the bay caused by soil erosion and runoff associated with forestry, agriculture and subdivision is likely to have a range of negative effects on the benthic community. Also towed-gear fishing, dredging and trawling homogenise benthic habitat structure (reduce habitat heterogeneity) and facilitate sediment resuspension as well as causing removal and direct physical damage to benthic biota. There is an imperative to seek to mitigate these effects and look at ways to restore the benthic community including the commercial shellfish species. In this context, my central hypothesis was that enhancement of the benthic habitat by returning waste shell to the seabed would increase oyster production for the fishery. Related to this main goal of oyster fishery enhancement, a primary objective of the study was to fill knowledge gaps relating to the biology and ecology of the oyster in Tasman Bay. The second main topic of my thesis was to investigate how this form of habitat enhancement would alter the benthic community structure, and potentially aid in restoration of the wider ecosystem in the bay. I sought to link the twin goals of fishery enhancement and ecological restoration by considering potential management measures to promote a sustainable oyster fishery and at the same time facilitate ecological restoration within Tasman Bay. The investigations focused on four main themes: temporal patterns of oyster larval abundance, spatial patterns of spatfall and larval dispersal, effects of habitat enhancement on oyster population productivity, and effects of habitat enhancement on the benthic faunal community. Laboratory and field studies were conducted between October 2004 and May 2009. A peak period of oyster reproductive activity began in late spring and continued through summer in each year. Maximum rates of adult oysters brooding larvae were 17% in November 2004 and 2005, and 23 % in December 2006. Over the entire summer breeding period it was estimated that 55 to 78 % of adult oysters incubated larvae. A very low level of brooding activity (1 %) occurred during winter. Temporal trends in larval settlement closely tracked brooding patterns. Settlement on collectors deployed in Tasman Bay was greatest between November and January, and there were very low rates in winter. Results are useful in optimising the timing of substratum deployment in an enhancement program for the oyster fishery. Spat settlement density was strongly related to background adult oyster density. Spat settlement on experimental arrays deployed through the water column only occurred within a narrow vertical range very close to (<1 m above) the seabed. If suitable habitat is available for settlement, oysters tend to settle within a few hours after release, but approximately half of the larvae settled in a laboratory experiment were capable of remaining viable for several days. Oyster distribution assessed at the scale of the shellfishing industry’s annual biomass survey (median distance between sample tows ~ 1 km) is adequate to broadly predict spat settlement distribution in the subsequent settlement season, and the distribution of mature oysters is a key determinant in the placement of shell for habitat enhancement to maximise spat settlement. Deployment of waste whole scallop shell on the seabed as settlement substratum increased oyster spat density significantly. Available settlement surface on enhanced shell plots decreased by 82% in the five months after deployment, due to fouling by numerous invertebrates and sedimentation. Survival of oysters recruited to enhanced habitat was generally very low, and varied greatly among 4 experimental sites and through time. After 3+ years, survival among site/treatment combinations ranged from 0% to 0.04%. At the site where survival was greatest, the absolute density of oysters surviving to 3.41 years on enhanced habitat was estimated as 0.4 m⁻². This equated to an increase in relative density of commercial sized oysters from ~0.01 m⁻² prior to enhancement, to ~0.14 m⁻² at the end of the experiment, and demonstrated that habitat enhancement can elevate adult oyster densities to commercial levels on areas of seabed where oysters were previously below threshold densities for commercial fishing (0.02 m⁻²). Peaks in mortality occurred within experimental plots when oysters were less than one year old, and three years old. Growth modeling indicated that after 4.25 years, 98% of living oysters would attain legal size (≥ 58mm length), and 92% would attain sufficient shell depth (≥ 20 mm) to provide high grade (grade A in the industry) meat. Shell depth was a better morphometric predictor of meat weight than either shell height or shell length. The species assemblages on the shell-enhanced habitat were distinct from those on adjacent non-enhanced seabed. Measures of taxonomic and functional richness, faunal densities, and taxonomic redundancy within functional groups all increased in enhanced habitat. Beta and gamma diversity also increased due to patchiness of the habitat created within enhanced experimental sites. Large scale habitat enhancement in Tasman Bay via the deposition of waste shell on the seabed is likely to confer benefits to ecosystem function associated with those community level effects. To sustain an oyster fishery in Tasman Bay, an ecosystem-based approach to fishery management is recommended to facilitate restoration of benthic habitats and communities and to help maintain ecosystem function supporting all components of the benthic community, including the oyster population. Planning and implementation of a combination of specific management measures including habitat enhancement, rotational fishing, permanent exclusion of towed fishing gear from a network of protected areas, and integration of the management of the oyster, scallop, and finfish fisheries would provide the best chance for restoration and maintenance of a sustainable oyster fishery.

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28

Cole, Russell Gavin. "Distributional relationships among subtidal algae, sea urchins and reef fish in northeastern New Zealand." Thesis, University of Auckland, 1993. http://hdl.handle.net/2292/1912.

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Interactions among large brown macroalgae, sea urchins, and fishes were investigated in northeastern New Zealand during the period 1988 - 1993. The Cape Rodney to Okakari Point Marine Reserve was the site of many of these investigations. The patterns of abundance of large brown macroalgae and urchins down depth gradients over a wide geographic range were compared with those reported from earlier studies, and 3 major trends were identified. First, the fucoid alga Carpophyllum flexuosum now occurs at many sites which are exposed to wave action, in contrast to earlier studies. This alga occurred most abundantly on urchin-grazed coralline flat areas. Second, at four sites in the Marine Reserve, the densities of the echinometrid urchin Evechinus chloroticus decreased with increasing depth, rather than reaching maximal densities at mid-depths, as had previously been described. Finally, at sites of decreased exposure to wave action, the coralline flats habitat did not occur at all, and dense stands of. C. flexuosum occurred, in conjunction with the ubiquitous laminarian alga, Ecklonia radiata. Following the discovery of this new algal component to exposed rocky reefs, a more detailed study of its population characteristics was initiated. The population size structure of C. flexuosum on coralline flat areas was markedly different from that of the same species in sites sheltered from wave action. These differences occurred at both offshore islands and sites near Leigh, suggesting that it was a general pattern. C. flexuosum plants on coralline flats were smaller than those from sheltered sites, and had a greater number of smaller laminae, heavier stipes, and a greater degree of branching. There was some evidence of temporal change in the morphology of C. flexuosum from coralline flats. Comparisons between a site with C. flexuosum and a site with coralline flats suggested that the activity of fish was 75% lower in the vegetated than in the unvegetated site, and the feeding rate in the vegetated site was less than 50% that in the unvegetated site. I speculate that future effects on fish activity of the invasion of C. flexuosum into a habitat which previously lacked macroalgal vegetation may depend on changes in the morphology of plants. An investigation of many aspects of the biology of E. chloroticus in different habitats was undertaken. Analysis of the body dimensions of E. chloroticus suggested that this species was relatively tall compared to other echinometrids (average ratio of test height: test diameter = 0.54), Comparisons among habitats with differing amounts of vegetation revealed only small differences in the relationship between test diameter and test height. Small E. chloroticus (<40 mm test diameter) lived in crevices, while larger individuals grazed freely over the substratum. In vegetated habitats, the crevice-dwelling habit was maintained at test diameters about l0 mm greater than in unvegetated habitats. Very small (<20 mm test diameter) E. chloroticus frequently covered themselves with shell. Population size structures of E. chloroticus within the Cape Rodney to Okakari Point Marine Reserve were bimodal; other localities had unimodal populations. Modal sizes varied among localities, with smallest modes (50-60 mm TD) being found at Inner Hauraki Gulf sites, and largest modes at the offshore Mokohinau Islands (70-80 mm TD). Habitat did not predictably affect population size structure. A bimodal population structure was maintained at Waterfall Reef rock flats throughout the 5-year study period. Gonad size showed seasonal fluctuations at several sites, being greatest in summer. There were few consistent differences in gonad size between biological habitats. Gonad colour varied among sites and habitats, with orange gonads generally being more prevalent in vegetated habitats, and black gonads being represented more in unvegetated habitats. Smaller urchins had greater proportions of orange gonads, while larger urchins had greater proportions of brown and black gonads. Although highly variable among individual urchins, movement of E. chloroticus was greater at unvegetated sites (0.7 m per 5 days) than at vegetated sites (0.4 m per 5 days), in the Marine Reserve. Feeding of E. chloroticus was studied at a number of sites in the Marine Reserve. Urchins frequently consumed drift algae, particularly E. radiata. C. flexuosum was consumed at less than half the rate of other macroalgae in several laboratory feeding experiments, and was chosen least frequently in a field assay of feeding preferences among 8 species of macroalgae. Boosting densities of E. chloroticus in stands of E. radiata to 60 m-2 led to destructive grazing of plants over a 2 month period - at lower densities, the urchins dispersed. Densities of C. flexuosum were effectively unchanged when urchin densities were increased to these elevated levels. As a result of these observations I speculate that feeding preferences of E. chloroticus may have a role in allowing C. flexuosum to survive on coralline flats. In a laboratory experiment, urchins from a feeding aggregation did not graze algae at higher rates than individuals from outside aggregations. Diets of both E. radiata and C. flexuosum consistently produced similar gonad volumes in urchins held in the laboratory, although gonad volumes produced were low. A preliminary experiment suggested that C. flexuosum from exposed sites was consumed at lower rates than C. flexuosum from sites which were sheltered from wave action. These differences in palatability are mirrored in the formation of stable borders between coralline flats and C. flexuosum of the sheltered morphology, and the ability of C. flexuosum of the exposed morphology to survive in the coralline flats habitat. The fish fauna of the Cape Rodney to Okakari Point Marine Reserve was shown to be different from that of a nearby area. A number of species were more abundant within the Marine Reserve. Subsequent surveys showed that there were differences in abundances of 3 large carnivorous fishes among sites within the Marine Reserve, and that population size structure and the distance within which divers could approach one species, (Pagrus auratus), clearly varied between areas within the Marine Reserve. Mean standard length of P. auratus in the central marine reserve was 40% larger than that of P. auratus outside the central marine reserve, and the average minimum approach distance was 70% less in the central marine reserve. Feeding of fish by humans in the central part of the Marine Reserve was suggested to be the main cause of the differences in responses to divers. Population size structure of, and crevice occupancy by, E. chloroticus, clearly differed between the Marine Reserve and an adjacent area, with bimodal population size structures and a 10 mm greater size of crevice occupancy occurring in the Marine Reserve. The implications of these findings for extrapolating from experiments done in one area to other areas are discussed. The major biological components of rocky reef habitats identified in this study were broadly similar to those identified in previous studies in northeastern New Zealand, and have parallels in overseas studies. Long term changes to the flora of rocky reefs in northeastern New Zealand have occurred, and appear to persist by a mechanism which had previously been discounted. Similar processes to those observed in overseas studies appear to maintain habitats (consistent recruitment of algae or urchins to habitats which they dominate), or cause them to change from one habitat state to another (e.g. grazing outbreaks by urchins). However, the predictability of the persistence of these habitats at a particular site appears to be low. Further, the precise mechanisms whereby habitats may change from one to another may also be unpredictable. I argue that there is little scope for general statements concerning the spatial and temporal occurrence, or mode, of habitat transitions on temperate subtidal reefs. This study emphasises the value of repeated descriptions of patterns of abundance, and highlights problems of extrapolation and generalisation in marine ecology. Insufficient information exists at present to comment adequately on the persistence of subtidal habitat types. This may in part stem from the types of information which have been collected in the past. Methodological problems with the use of quadrats to sample densities of organisms in areas of differing topography are therefore addressed. In conclusion, it is suggested that sampling protocols which incorporate a variety of information, gathered over as wide an area, and as intensively as possible, should be used in future research of this type.

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Bickel, Tobias O., and n/a. "Lagarosiphon major : an introduced macrophyte and its ecological role in the littoral of Lake Dunstan, New Zealand." University of Otago. Department of Zoology, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070323.131753.

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The littoral of Lake Dunstan, Central Otago, New Zealand, is dominated by the introduced submersed macrophyte Lagarosiphon major (hereafter Lagarosiphon) which effectively excludes native macrophytes from most of the littoral. Lake Dunstan is a large hydro lake that was - after reaching its operational water level in 1993 - rapidly colonized by Lagarosiphon from upstream sources. Because of its extensive biomass and growth, it is believed the macrophyte plays an important part in the lake ecosystem but also that it requires frequent management to allow for recreational activities, to restore aesthetic values of beaches and especially to prevent further spread into unaffected waterways. To assess the integration of Lagarosiphon into the lake ecosystem and possible impacts of extensive macrophyte removal a 3 year study was initiated focusing on invertebrate and fish distribution and diet in relation to Lagarosiphon. A stable isotope analysis was used to reconstruct carbon flows and trophic structure within the littoral of Lake Dunstan. Additionally, a small scale weed management experiment was carried out to assess possible impacts of macrophyte removal on invertebrates and fish. Lagarosiphon harboured a high density and diversity of macroinvertebrates. The invertebrate community was dominated by mollusc species in terms of biomass and abundance. There was little temporal and spatial variation in invertebrate distribution and communities on a large scale (lake-wide variation), but there were differences in invertebrate biomass on a smaller scale in relation to the location of samples within the macrophyte belt. Invertebrate biomass was lowest at the bottom of the dense macrophyte beds. The positive association of common bully (Gobiomorphus cotidianus: Eleotridae) with the dense Lagarosiphon stands and a diet - mainly consisting of invertebrates common on Lagarosiphon - suggested the important role of this macrophyte as a provider of food and shelter for small fish species. Brown and rainbow trout (Salmo trutta, Oncorhynchus mykiss: Salmonidae) diet was dominated by invertebrate species common on this macrophyte as well. Results of the stable isotope analysis suggested a secondary role of Lagarosiphon in the lake food web as a surface provider for the growth of epiphytic algae that appeared to be a major primary producer in the littoral of Lake Dunstan. Detritus (FPOM), assumed to consist partly of decaying Lagarosiphon, played a less important role as a base for the food chain. The main carbon flow pathway was from the primary producers (epiphyton - FPOM) through primary consumers (Mollusca, Chironomidae, Trichoptera) through to the top predators (tertiary consumers: trout and bullies) in the system. A small scale experiment on the influence of macrophyte harvest, i.e. the cutting of channels into dense macrophyte beds, showed that a partial removal of macrophyte biomass could help achieve several management goals: it not only reduced macrophyte biomass to enable recreational activities but also had no negative impacts on invertebrate biomass and diversity. The channels even increased invertebrate abundance and biomass in the treated compared to the untreated control plots along the cut edges. Regrowth of Lagarosiphon was rapid, with the cut channels being completely overgrown within 4 months. All these results taken together suggested a major role of Lagarosiphon in the littoral of Lake Dunstan. Lagarosiphon supported a species rich invertebrate community and was the main provider of food and shelter for fish in this lake. A partial removal of macrophyte biomass might be a more suitable management option than large scale eradication to avoid negative impacts on the lake ecosystem. The most important aspect in management of this weed remains the prevention of further spread into pristine waters.

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30

Crow, Shannan Kyle, and n/a. "Evolutionary ecology of non-diadromous galaxiid fishes (Galaxias gollumoides and G. �southern�) in Southern New Zealand." University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081124.095647.

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Coexisting species are interesting from evolutionary and ecological perspectives. Sympatry can provide insights into mechanisms that allow stable long-term coexistence, such as niche partitioning, character displacement, interspecific competition and species boundaries. In New Zealand streams, a flock of closely related non-migratory galaxiid fishes exist throughout eastern South Island (Galaxias vulgaris sensu lato). These fishes are largely parapatric, but recent studies have found streams that contain coexisting populations of two newly discovered galaxiids (Galaxias �southern� and G. gollumoides). In such streams there is a cline from allotopic (sections of streams containing predominantly one species) G. �southern� (lower altitudes) to allotopic G. gollumoides (higher altitudes), with a syntopic (both species) transition section. Such coexistence makes G. �southern� (yet to be formally described) and G. gollumoides ideal for examining the ecology and evolution of sympatric taxa. Very little is known about these two taxa. This thesis aims to detail the morphology, ecology and genetic differentiation between G. �southern� and G. gollumoides. These factors will be used to address separate species status and the possibility of interspecific competition. Data will also be used to examine resource and morphological shifts in either species between syntopy and allotopy, which maybe consistent with character displacement theory. All fish collected for analysis were first classified as G. �southern� or G. gollumoides by eye and by mtDNA. Morphological and ecological (habitat use and diet/isotope enrichment) differentiation between the two species were examined from three sympatric streams (streams containing allotopic and syntopic sites; representing three separate catchments) and four allopatric streams (streams containing only allotopic sites; representing two separate catchments). For sampling purposes, sympatric streams were subdivided into lower (allotopic G. �southern�), mid (syntopic) and upper (allotopic G. gollumoides) sections. We used this sampling regime to test for character displacement (i.e. ecological and morphological shifts between syntopy and allotopy). Diet, stable isotope, genetic structuring and hybridisation (amplified fragment length polymorphisms) were analysed from the three sympatric streams. Artificial stream channels were also used to observe the influence of interspecific competition on resource use over a complete diel cycle. G. �southern� and G. gollumoides were found to be morphologically distinct, differing significantly in 21 of 25 morphological measurements. The two species were also segregated ecologically with G. �southern� preferring shallower water, coarser substrate, and higher water velocity, feeding predominantly on mayflies (Ephemeroptera). In contrast, G. gollumoides preferred deeper water, finer substrate and lower water velocity, feeding predominantly on terrestrial invertebrates. Dietary segregation was also reflected by differences in [delta]�� Carbon and [delta]�⁵ Nitrogen enrichment. Morphological shifts consistent with character displacement were seen in overbite size and mouth size, but neither trait showed consistent statistical differences within and across streams. Ecological shifts were seen in distance to the nearest cover, with G. gollumoides being found further away from cover in syntopy and G. �southern� being found the same distance away from cover in syntopy and allotopy. In artificial stream channels, resource use of both species was not affected by the presence of a congener, but both species used faster water velocities during the night while remaining ecologically distinct. AFLP analysis revealed distinct genotypic clustering between these species with no F1 hybrids. Fine-scale genetic structuring was also observed within both species among streams, and among sites within streams. The minimal effect of a congener on resource use suggests that interspecific competition is not a strong force shaping sympatric populations of Southland galaxiids. This is also reflected by the lack of consistent morphological shifts between allopatry and sympatry. Similarly, character displacement does not seem to be a strong influencing G. �southern� and G. gollumoides. Diel cycles influenced niche expression in both fishes suggesting that abiotic factors may be important in structuring freshwater fish communities in Southland. The fine-scale genetic structuring within both species suggests limited conspecific genetic mixing and movement within streams, which possibly reflects drainage evolution. The absence of F1 hybrids suggests reproductive isolation between G. �southern� and G. gollumoides which may be associated with assortative mating. The present study provides evidence for the separate status of these sympatric fishes under several species concepts. There is conclusive evidence for morphological, ecological and genetic differentiation between sympatric G. �southern� and G. gollumoides, and such segregation maybe associated with long term coexistence in nature. Key words: coexistence, ecology, morphology, genetics, G. �southern�, G. gollumoides.

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31

Ling, Nicholas. "The development, ultrastructure and biomechanics of the swimbladder of the New Zealand snapper, Pagrus auratus." Thesis, University of Auckland, 1990. http://hdl.handle.net/2292/2012.

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The eggs and larvae of the New Zealand snapper Pagrus auratus are pelagic with early buoyancy provided by dilute body fluids. The swimbladder begins to develop on the third day after hatch from a dorsal evagination of the gut tube. Communication w1h the gut is lost on about the tenth day following pneumatic inflation at around day eight. At this age the gas gland system appears fully functional and capable of secreting gas. By the age of settlement at around 30 days the swimbladder is a fully functional replica of the adult form except for the lack of a resorbent capillary system which does not develop until later in juvenile life. The swimbladder of the adult is of the euphysoclist form with a dorsally located resorbent oval area and sits high in the pleural cavity. The ventral tunica externa is firmly attached to the connective tissue lining the pleural space. The adult swimbladder displaces 5.6% of the volume of the body and its volume is regulated to provide near neutral buoyancy. The connective tissue integument provides almost no restriction to volume changes brought about by vertical movements of the fish and the swimbladder obeys Boyle's Law for physiological pressure changes. The ability of the connective tissue of the tunica externa to accommodate large tissue strains is due to massive regular crimping of otherwise straight collagen fibrils allowing reversible extensions up to 130%. In all other respects however the tissue structure of the tunica externa is consistent with a tissue providing an active mechanical role. The fibrillar morphology and physicochemical properties of swimbladder collagen is consistent with the vertebrate type I form however there are interesting variations in collagen form distributed throughout the swimbladder. Fibrillar morphology of the highly extensible tunica interna is significantly different to that of the tunica externa and appears to play very little mechanical rote. The extensibilty of the tunica externa appears to be regulated by physiological stress and related to the past history of tissue strain.

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32

Mason, Norman, and n/a. "Functional diversity and ecosystem-level processes in a short-tussock grassland." University of Otago. Department of Botany, 2006. http://adt.otago.ac.nz./public/adt-NZDU20061024.114054.

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Increased functional diversity has been linked to an increase in ecosystem level processes (ELPs), such as productivity, ecosystem reliability and invasion resistance. However, there has been no exact definition of functional diversity and it is not known which indices are appropriate for its measurement. Consequently, continuous indices have rarely been applied in examination of relationships between functional diversity and ELPs and little is known of the mechanisms linking functional diversity to ELPs. This thesis begins by providing an exact definition of functional diversity, identifying its primary components and devising appropriate continuous indices for the measurement of these components. These indices are used to examine relationships between functional diversity and three ELPs - biomass production, the reliability of biomass production and invasion resistance. Initially these examinations are conducted using a mechanistic community assembly and dynamic model. This model is based on physiological and morphological character data for species occurring in the short-tussock grassland communities of the Luggate field experiment, in the southern South Island, New Zealand. Finally, relationships between functional diversity, mean annual community cover and the reliability of cover are examined in the Luggate field experiment. Functional composition (i.e. the actual functional characters of the species within a community) appeared to exercise the greatest influence on ecosystem reliability in the community assembly and dynamic model. However, there was evidence that functional diversity increased the reliability of productivity via the co-variance effect. Functional composition also exercised the greatest influence over mean annual productivity in the model, almost completely accounting for the negative relationship between functional diversity and mean annual productivity. These results are respectively analogous to the positive and negative selection effects seen in species richness / ELP relationships. Both functional diversity and functional composition influenced community invasion resistance in the model. Here, increased functional diversity acted to increase community resistance to invasion. In the Luggate field experiment, neither functional diversity nor functional composition was related to mean annual cover, though species richness was positively related to it. Increased functional diversity acted to increase the reliability of cover. However, this did not appear to occur via the co-variance effect, but as a result of increased functional diversity increasing consistency in the species composition of experimental plots through time. These results demonstrate that studies examining functional diversity must account for the effects of species identity. A framework is proposed to accommodate selection effects associated with functional diversity / ELP relationships. The usefulness of the co-variance effect as a testable mechanism linking functional diversity to ecosystem reliability in the field is questionable, as there is no objective way of measuring it.

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Leung, Tommy Ling Fong, and n/a. "Interspecific and intraspecific interactions of trematodes parasitising the New Zealand cockle Austrovenus stutchburyi." University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20090105.160127.

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Most organisms are rarely infected with just a single species of parasite and are usually simultaneously infected with a range of species. Thus, the parasite fauna of a host represents an entire community composed of multiple individuals from many different species. In nature, it is within the host that parasites can encounter conspecifics and individuals from other species. As in any ecosystem, while such interactions between parasites can be antagonistic due to competition or conflicting interests, association between different species can also be beneficial. In this thesis, I investigated patterns of associations between parasites in the New Zealand cockle Austrovenus stutchburyi through a combination of descriptive and experimental studies employing both standard ecological field techniques and molecular biology methods. It was found that the presence and infection intensity of various parasites species are not independent of each other. Among cockles, an association was found between two trematode taxa, i.e. between the infection intensity by foot-encysting echinostomes and the metacercariae of Gymnophallus sp. It was also found that the presence of the parasitic copepod Pseudomyicola spinosus was associated with greater infection intensity by the echinostomes but not Gymnophallus sp. While it was postulated that the positive association between the echinostomes and Gymnophallus sp. was due to the latter�s preference to infect cockles that are stranded on the sediment surface as a result of heavy echinostome metacercariae burden in their foot, a field experiment found that Gymnophallus cercariae did not preferentially infect cockles that have been forced to remain above the sediment surface as opposed to those that were forced to remain buried. Meanwhile, the two species of echinostomes known to encyst in the cockle�s foot, Acanthoparyphium sp. and Curtuteria australis, were found to represent cryptic species complexes. The presence of such cryptic species means that it is possible that some potential interspecific interactions are overlooked. A study of the population structure of Gymnophallus sp. found that each cockle contains multiple genetically distinct individuals and that clonal individuals rarely co-occur in the same cockle. This adds to the growing body of evidence suggesting that in addition to acting as a means of reaching the definitive host, the second intermediate host also acts to promote genetic diversity by accumulating cercariae shed by multiple first intermediate hosts in the environment. An experimental infection study conducted with Curtuteria australis cercariae deriving from singly-infected first intermediate hosts revealed that different clonal lineages varied with respect to their contribution to host manipulation. It was found that while certain lineages have a preference for host manipulation, others tend to adopt a "hitch-hiker"-type life history strategy. However, this genetic predisposition was also found to be a phenotypically plastic trait, as the presence of a higher number of manipulators seems to encourage newly-arrived cercariae to become manipulators, regardless of clonal lineage. This thesis provides evidence that patterns of interactions can affect various aspects of parasite life history. Apart from host condition, parasites can also be affected by other parasites. Studying the dynamics of mixed infections can provide informative insights for evolutionary and ecological research.

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Merican, Faradina. "A Taxonomic and Ecological Study of Periphytic Cyanobacteria in Kaituna River and Its Tributaries, Banks Peninsula, New Zealand." Thesis, University of Canterbury. School of Biological Sciences, 2013. http://hdl.handle.net/10092/8615.

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Most of the detailed studies on periphyton in New Zealand rivers and streams have focused on diatoms. Despite the recent rise of interest in potentially toxic cyanobacterial mats, knowledge of the diversity and ecology of these and other macroscopic growth forms is incomplete. A taxonomic survey was made on periphytic cyanobacteria at 100 locations along Kaituna River and a 1st to 3rd order tributary stream. Samples were taken from runs, riffles and pools in shaded and unshaded locations and from varied substrata from January to December 2011. Descriptions were made of all macroscopic growths. Fifty-six morphospecies were identified of which 29 are new records for New Zealand. Crust components were the most diverse with 23 morphospecies followed by mats (16), gelatinous colonies (5) and epiphytes (7). Five appeared only after growth in enrichment cultures. Twelve morphospecies were isolated into cultures for use in polyphasic assessment. In 16S rDNA phylogenies, Placoma regulare and Heteroleibleinia fontana did not cluster with other members of their traditional families. Nostoc sp. 2 was positioned distant from other Nostoc strains. Comparison of 16S – 23S rRNA internal transcribed spacer compositions for seven mat-forming oscillatorialean morphospecies confirmed their recognition as distinct morphospecies. Amplified fragment length polymorphisms were used to investigate genetic diversity of Nostoc verrucosum in relation to dispersal. This indicated that local dispersal is dominant while cross-catchment dispersal is probably infrequent. Light intensity, substratum type and water conductivity were significant factors influencing spatial patterns of distribution. Higher diversity of crusts, mats and gelatinous colonies was recorded in unshaded locations. Mats and gelatinous colonies were most diverse in Kaituna River and crusts in second to third order streams. Morphospecies in water with high conductivity were restricted to those locations. Spates had a major effect on temporal distribution. An increase in frequency and intensity of spates in spring and winter resulted in greater reduction in cover. Smaller spates caused partial removal followed by rapid regrowth within a week. Major spates caused complete removal of visible cover with re-colonization occurring within three to four weeks. This study has provided a first detailed account of cyanobacterial diversity and ecology in a New Zealand catchment. It provides a basis for long-term monitoring at this site of the effects of changes in climate and in human activities in the catchment.

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Durrett, Melody S. "Spatial variability in plant and soil properties on New Zealand seabird islands, and the effects of introduced rats." Thesis, University of Alaska Fairbanks, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3624440.

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Seabirds are ecosystem engineers with two major impacts on island ecosystems: they bring large quantities of marine nutrients to the terrestrial environment in the form of guano, carcasses, feathers, eggs, and spilled food, and they disturb the soil surface. Burrowing seabirds can denude the soil surface of all seedlings and leaf litter, plowing them under and loosening the soil. However, seabirds are colonial, and burrows are not even spaced over the surface of an island, producing spatial variability within a single island that might reveal how seabird activities control island ecosystem function.

In this dissertation I review seabird island ecology in general, focusing on how introduced predators have reduced seabird populations, interrupting seabird activities and altering island ecology. I then describe three studies designed to quantify the effects of seabirds on soil and plant properties within individual islands and compare these patterns across islands varying in seabird density, especially where seabirds have declined because of invasive rats (Rattus spp.).

I used geostatistics to quantify the spatial variance in seabird burrows and various soil and plant properties (including soil and leaf N) within six islands of low, intermediate, and high burrow density. I found that burrow density was not a good predictor at within-island scales, and though the variance of some soil properties (pH, soil δ¹⁵N, and soil compaction) peaked on intermediate islands as expected, variables reflecting the soil N cycle (net ammonification and net nitrification potential, NH₄⁺ and NO₃^-) continued to increase in variability on very high-density seabird islands. Ecosystem properties clearly responded to seabirds at different spatial scales, possibly because seabirds deposit guano at different spatial scales than they dig.

Using data within three rat-invaded and three rat-free islands, I used structural equation models to examine seabird influences on N cycling. I found some mechanisms that were constant across islands, such seabird-related decreases in soil water and pH, but other mechanisms differed between invaded and uninvaded islands, suggesting that rats manifest an alternative state for island N cycles, which may or may not be reversible.

Finally, I investigated whether plants can use ammonia (NH₃ gas) volatilized from seabird islands, measuring NH₃ concentrations across 10 islands and within a single island where I also experimentally manipulated plant N demand. Both rat-invaded and rat-free islands produced meaningful concentrations of NH₃ gas, and multiple plant species including Melicytus ramiflorus and Coprosma macrocarpa used it for up to 20% and 30% (respectively) of their total leaf N. Plant N demand modified NH₃ uptake, suggesting that plants located not on seabird colonies, but downwind, may benefit the most from this gaseous N source.

I suggest that future studies attempt to estimate thresholds of burrow density at which seabird-controlled ecosystem properties can recover from rat invasion.

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Mattern, Thomas, and n/a. "Marine ecology of offshore and inshore foraging penguins : the Snares penguin Eudyptes robustus and Yellow-eyed penguin Megadyptes antipodes." University of Otago. Department of Zoology, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070502.150734.

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Seabirds have become adapted for foraging in an oceanic environment that can be highly dynamic. Oceanographic processes determine the spatial distribution of seabird prey, while seasonality often has a temporal influence on prey availability. In penguins, these factors are reflected in the different species� foraging strategies. Penguins can broadly be categorized as inshore foragers that live in subtropical to temperate regions and profit from a stable food supply throughout the year close to their breeding sites, and offshore foragers that breed in a pelagic environment at higher latitudes where oceanographic processes and seasonality create much more dynamic, temporally limited prey situations. In this light, offshore foragers can be expected to be much more flexible in their foraging behaviour so as to quickly respond to changes in a dynamic marine environment, while inshore foragers are more likely to exhibit predictable foraging patterns. I examined the foraging ecology of two New Zealand penguin species - the offshore foraging Snares penguin Eudyptes robustus and the inshore foraging Yellow-eyed penguin Megadyptes antipodes and how their foraging strategies reflect an adaptation to the marine environment they exploit. Diet composition of breeding Snares penguins (incubation and early chick-guard) was determined using the water-offloading method. Before the chicks hatched, the penguins generally brought little food back from their long foraging trips. During chick-guard, the stomach contents comprised mainly of crustaceans (~55%), fish (~24%) and cephalopods (~21%). However, the presence at times of many fish otoliths and squid beaks suggests that the latter two prey classes may play an even more important role in the adults� diet than the simple percentages based on mass suggest. The penguins� nesting routines were strongly synchronised between the years and correlated with the onset of the spring planktonic bloom. Using GPS data loggers and dive recorders I found that during the incubation phase, male penguins that performed long (ca. 2 week) foraging trips exhibited a strong affinity to forage in the Subtropical Front some 200 km east of the Snares. At that stage (late mid-October) the front featured elevated chlorophyll a concentrations, a pattern that can be observed every year. Thus, it seems that the front represents a reliable and predictable source of food for the male penguins. After the males returned, the female penguins also performed long foraging trips (<1 week) but never reached the front, primarily because they had to time their return to the hatching of their chicks. After the chicks had hatched, the female Snares penguins were the sole providers of food. At this stage, the penguins performed short foraging trips (1-3 days) and foraged halfway between the Snares and Stewart Island (ca. 70-90 km north of the Snares), where nutrient-rich coastal waters flow eastwards to form the Southland Current. The penguins concentrated their diving effort in these waters, underlining the importance of the warm coastal waters as a food source for breeding Snares penguins. However, diving behaviour between 2003 and 2004 differed with penguins searching for prey at greater depths in the latter year. This underlines the Snares penguins� behavioural flexibility in response to a changing marine environment. The Yellow-eyed penguins as typical inshore foragers showed very consistent foraging patterns at all stages. GPS logger deployments on penguins at Oamaru revealed that the birds foraged almost exclusively at the seafloor and targeted specific areas that featured reefs or epibenthic communities. As a result, the penguins� at-sea movements appeared conservative and at times almost stereotypic. Nevertheless, a comparison of Yellow-eyed penguins breeding on the adjacent Codfish and Stewart islands revealed a degree of plasticity in the species� foraging behaviour. Birds from Codfish Island extended their foraging ranges considerably and switched from primarily bottom to mid-water foraging during the post-guard stage of breeding. It seems likely that this switch is a result of enhanced feeding conditions (e.g. increased prey abundance/quality) in an area further away from the island, but the time required to get there renders this strategy not viable when chicks are small and need to be guarded and fed on a daily basis. As such, the change of behaviour represents a traditional pattern rather than a dynamic response to a sudden change in the marine environment. In comparison, penguins from Stewart Island showed consistent foraging patterns during all stages of breeding. Given the high levels of chick starvation on Stewart Island, the lack of plasticity in foraging behaviour is surprising and might indicate that Yellow-eyed penguins find it difficult to react quickly to a sub-optimal food situation. Overall, it seems that Yellow-eyed penguins show a specialisation for a consistent benthic environment and, thus, lack the behavioural flexibility apparent in Snares penguins, which find their food in a changing pelagic marine environment.

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Gatehouse, Hazel A. W. "Ecology of the naturalisation and geographic distribution of the non-indigenous seed plant species of New Zealand." Diss., Lincoln University, 2008. http://hdl.handle.net/10182/1009.

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The naturalisation and subsequent spread of non-indigenous plant species (NIPS) is a major problem for most regions of the world. Managing plant invasions requires greater understanding of factors that determine initial naturalisation and distribution of wild NIPS. By the year 2000, 2252 NIPS were recorded as wild (1773 fully naturalised and 479 casual) in New Zealand. From published literature and electronic herbaria records, I recorded year of discovery of wild populations, and regional distribution of these wild NIPS. I also recorded species related attributes hypothesised to affect naturalisation and/or distribution, including global trade, human activities, native range and biological data; and regional attributes hypothesised to affect distribution, including human population densities, land use/cover, and environmental data. I used interval-censored time-to-event analyses to estimate year of naturalisation from discovery records, then analysed the importance of historical, human activity, biogeographical and biological attributes in determining patterns of naturalisation. Typically, NIPS that naturalised earlier were herbaceous, utilitarian species that were also accidentally introduced and/or distributed, with a wide native range that included Eurasia, naturalised elsewhere, with a native congener in New Zealand. In the year 2000, 28% of wild NIPS occupied only one region, 18% occupied two regions, decreasing incrementally to 2.5 % for nine regions, but with 13.5% occupying all ten regions. I used generalised linear models (GLMs) with binomial distribution to determine predictors of whether a wild NIPS occupied ten regions or not, and GLMs with Poisson distribution for wild NIPS occupying 0 – 9 regions. As expected, the dominant effect was that species discovered earlier occupied more regions. Utilitarian wild NIPS that were also accidentally introduced and/or distributed, and wild NIPS with a native congener tended to be more widely distributed, but results for other attributes varied between datasets. Although numbers of wild NIPS recorded in regions of New Zealand were sometimes similar, composition of wild NIPS was often very different. I used nonmetric multidimensional scaling (NMDS) to determine dissimilarity in composition between regions. Then, after reducing correlation between predictor variables using principal components analyses (PCAs), I tested the importance of regional variables in determining the regional composition of wild NIPS using metaMDS. The density of human populations best explained the dissimilarity in composition, but temperature gradients and water availability gradients were also important. In the year 2000 more than 1100 (60%) of the 1773 fully naturalised NIPS in mainland New Zealand had each been recorded in Northland/Auckland and Canterbury, and at the other end of the scale, Southland and Westland each had fewer than 500 (30%). I used GLMs to analyse the importance of people and environment in determining the numbers of wild NIPS in each region. Because I conducted multiple tests on the same dataset I used sequential Bonferroni procedures to adjust the critical P-value. Only human population density was important in explaining the numbers of NIPS in the regions. Overall, humans were the dominant drivers in determining the patterns of naturalisation and spread, although environment helps determine the composition of NIPS in regions. Incorporating human associated factors into studies of wild NIPS helps improve the understanding of the stages in the naturalisation and spread process.

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Negro, Sandra Silvia. "Reproductive ecology and life history trade-offs in a dimorphic polygynous mammal, the New Zealand fur seal." Thesis, University of Canterbury. School of Biological Sciences, 2008. http://hdl.handle.net/10092/2505.

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Polygyny is the most common mating system in mammalian species (95%), yet our understanding of polygynous systems and microevolutionary processes is still limited. Pinniped mating systems range from extreme polygyny (e.g. elephant seals) to sequential female defence by males and hence have often been used as models for mating system studies. Parentage analysis has enabled the examination of mating success, the identification of pedigrees, and the elucidation of social organisation, greatly enhancing our understanding of mating systems (Chapter 1). However, such analyses are not without pitfalls, with erroneous assignments common in open systems (i.e. when parental and offspring samplings are incomplete). We investigated the effects of the user-defined parameters on the accuracy of parental assignment using two commonly used parental allocation programme, CERVUS and PASOS (Chapter 2). We showed that inaccurate user-defined parameters in CERVUS and PASOS can lead to highly biased output e.g. the assignment rate at 95% CL of offspring with a sampled known mother to sampled males decreased from 58% to 32% when the proportion of candidate males sampled in the parameter options decreasing 4-fold. We found that the use of both CERVUS and PASOS for parentage assignment can increase the likelihood of correctly allocating offspring to sampled parents to 97% in our study system. Incorrect parental assignment can bias estimates of various biological parameters, such as lifetime reproductive success and mate choice preference, and hence bias ecological and evolutionary interpretations. Here, we propose solutions to increase the power of parentage assignment and hence decrease the bias in biological parameter estimates. In addition, we analysed the effects of the intrinsic bias in likelihood assignment approaches towards assigning higher probability of parentage on individuals with rare alleles and those with heightened offspring-parent matches, which increase with the number of homozygous loci (Chapter 3). We showed that, as a consequence of the algorithms employed in the programmes CERVUS and PASOS, heterozygote males with rare genotypes are assigned higher rates of parentage than males with common alleles. Consequently, where two males could both be biological fathers of a given offspring, parentage assignment will more often go to the male with the rarer alleles (most often in heterozygous loci). Thus, the commonly used parentage assignment methods may systematically bias the results of parentage analyses towards supporting the notion that females prefer more genetically unusual, most often heterozygous, males. Such a bias may sway investigators towards incorrectly supporting the concept that females choose genetically more unusual males for heterozygosity fitness benefits that underpin the good genes hypothesis, when in fact no such relationship may exist. In polygynous mammals, successful males mate with multiple females by competing with and limiting the access of other males to females. When the status of many males (age, size, health, genetic etc.) prevents them from achieving the primary mating tactic, theory predicts selection for a diversification of male mating tactics. Recent studies in pinnipeds have shown that observed male mating success was correlated to male paternity success in some species (elephant-seals), but not in others (grey seals). The existence of alternative mating strategies can explain those discrepancies. Chapter 4 implemented the guidelines provided in Chapter 2 and 3 and focused on the polygynous New Zealand fur seal Arctocephalus forsteri, predicting that 1) competition for females is likely to cause a diversification of male mating tactics; and 2) that alternative tactics can yield reproductive success. Our results indicated three male behavioural profiles; one corresponded to large territorial males and two illustrated a continuum of alternative tactics employed by non-territorial subordinate males. Our study highlights that holding a territory is not a necessary condition for reproductive success in a population of otariids. The degree of sexual size dimorphism in polygynous species is expected to increase with the degree of intra-sexual competition and in turn with the degree of polygyny. The life history of an individual is the pattern of resource allocations to growth, maintenance, and reproduction throughout its lifetime. Both females and males incur viability costs of mating and reproduction. However, male viability costs due to increase growth and male-male competition can be greater than female viability costs of mate choice and reproduction. Although an abundant literature on sexual dimorphism in morphology, physiology, and parasite infections is available, little is known on the intra-sexual differences in physiology and parasite infections associated to the reproductive success of different mating strategies in mammalian species. Chapter 5 examined the reproductive costs between territorial and subordinate males New Zealand fur seal related to their relative reproductive success using a multidisciplinary approach (behaviour, genetics, endocrinology, parasitology). We found that dominant New Zealand fur seal males endure higher reproductive costs due to the direct and indirect effects of high testosterone levels and parasite burdens. Our study highlights that holding a territory confers a higher reproductive success, but induces higher costs of reproduction that may impair survival. Understanding microevolutionary processes associated to polygynous systems is fundamental in light of the ongoing anthropogenic alteration of the environment through climatic variations and habitat reduction which ultimately affect opportunity for sexual selection and shape the life history trade-offs.

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Kilroy, Catherine. "Diatom communities in New Zealand subalpine mire pools: distribution, ecology and taxonomy of endemic and cosmopolitan taxa." Thesis, University of Canterbury. Biological Sciences, 2007. http://hdl.handle.net/10092/3678.

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Mire pools – shallow water-bodies in peat-forming wetlands – are a characteristic feature of New Zealand’s subalpine and alpine landscapes (>1000 m a.s.l.), yet have been the subject of few biological studies to date, particularly of their algal communities. This research focuses on these subalpine systems, and on their diatom communities. Despite the established paradigm of ubiquitous dispersal in micro-organisms, recent taxonomic studies have confirmed a distinctive endemic component in the freshwater diatom flora of the New Zealand / Tasmania / East Australian region. In this study, I examined benthic diatom communities from >320 freshwater sites throughout New Zealand and showed that over 20% of species may be confined to this region. The endemic diatom species had highest densities in stable, unproductive environments, particularly in high-altitude mire pools and tarns. In most cases, non-endemic taxa coexisted with endemic species. This raised questions about (1) the special characteristics of mire pools and tarns (since endemism might be expected in areas that have unique environmental characteristics), and (2) the mechanisms that have allowed existing endemic taxa to withstand displacement by common cosmopolitan taxa, which, by definition, are successful colonisers. I addressed these questions using two years of data from four subalpine mire pools (Bealey Spur wetland, near Arthur’s Pass, South Island). Physico-chemical data showed that water chemistry of these pools may differ from that of many Northern Hemisphere mire systems with respect to the relationship between pH and dissolved ions (especially calcium). This may be due to a combination of high pH rainfall, high rainfall quantities that limit the acidification effects of humic substances, and possibly vegetation differences. Therefore, some endemic taxa may be confined to these habitats because of the characteristic properties of the pools. I investigated the effects of disturbances in these stable environments. In the largest pool endemic species were shown to decline as wind-induced substrate disturbance increased. Endemic species also declined in two pools following small-scale experimental substrate disturbances. In all cases, non-endemic species remained unchanged. The distinctive species Eunophora cf. oberonica was responsible for much of the observed decline in endemic species abundances, which was evidently due to destruction of their specialised habitat within the cyanobacterial mats that made up the pool substrates. I explained pool-specific responses of diatom communities to disturbances by drawing on recent theory of invasibility as an intrinsic environmental property. I further investigated species coexistence by examining several general patterns of interspecific coexistence described for macroscopic organisms (e.g., abundance – occupancy, abundance – persistence). Patterns in mire-pool diatom communities were generally similar to those in larger organisms, and did not differ with respect to geographical range size (endemics vs. non-endemics), except at the scale of single pools. At this scale, endemic taxa, in particular E. cf. oberonica, can persist as dominant species. All the community analyses were underpinned by detailed taxonomic studies, from which I assessed over 40% of the more common species in the pools to be either endemic or likely to be endemic. Two species occurring in the study area are formally described as new species. Overall, this work highlights the vulnerability of this hidden component of New Zealand’s biodiversity to disturbances and environmental changes.

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40

Markey, Adrienne Selina, and n/a. "The evolution of fruit traits in Coprosma and the subtribe Coprosminae." University of Otago. Department of Botany, 2006. http://adt.otago.ac.nz./public/adt-NZDU20061206.160155.

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The flora of New Zealand has evolved largely in the absence of terrestrial mammals, the predominant frugivore guilds being birds and reptiles. The evolution of divergent fruit traits in New Zealand may be a consequence of different selection pressure by these two guilds, and two contrasting putative dispersal syndromes have been proposed for New Zealand fleshy fruited plants. Coprosma (Rubiaceae: subtribe Coprosminae) is a speciose and morphologically diverse genus, which is distributed throughout the South Pacific and which also produces variably coloured drupes. It was selected as a model genus to investigate the evolution of fruit traits within this context. For this purpose, a molecular phylogeny for the subtribe Coprosminae and Coprosma was inferred using parsimony, likelihood and split decomposition analysis on sequences from the 16rps intron of cpDNA and ETS and ITS region of nrDNA. Up to 32 species were included in the subtribal analyses, whilst 53 species of Coprosma were used in subgeneric studies. The basis for the variety of fruit colours seen in New Zealand was determined using histology and pigment extractions. To test the assumption that fruit traits among species evolved in concert under selection from frugivore guilds, fruit shape, size and nutrient composition were determined in order to test predictions that these would co-vary with fruit colour. In the Coprosminae, fleshy drupes have arisen from dry fruited schizocarps and with two possible reversals to semi-dry drupes. Within Coprosma, fruit colour was found to be evolutionarily labile and varied both among and within lineages, particularly within two main groups where fruit colour had shifted from orange to blue and white, or red, pink and black colours respectively. The evolution of novel (non-orange) fruit colours was restricted to New Zealand, as was the small-leaved, divaricate growth form, the combination of which has been associated with a putative reptile dispersal syndrome. Several trans-oceanic dispersals out of New Zealand were also inferred from the phylogeny, these extending into Australia, New Guinea and Hawai�i. In these instances, fruit colour did not appear change markedly after establishment in a new country. Within New Zealand, fruit sizes were found to vary with colour as predicted, although the majority of species produced small (< 8 mm), elliptical fruits. There was no clear association between fruit colour and fruit nutrient composition. It would appear that these small, succulent, carbohydrate-rich and lipid-poor fruits cater to a wide range of generalist frugivores. The variety of fruit colours in Coprosma stemmed from qualitative and quantitative differences in carotenoid and anthocyanin composition. The genetic basis for the control of these pathways is currently unknown, but it is assumed that a few regulatory genes can control a substantial amount of phenotypic variation. Considering the evolutionary history of Coprosma, it would appear that a history of recent and rapid speciation, hybridisation and reticulate evolution may have increased the tempo of fruit colour evolution in the genus.

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Kregting, Louise Theodora, and n/a. "The relative importance of mainstream water velocity and physiology (nutrient demand) on the growth rate of Adamsiella chauvinii." University of Otago. Department of Botany, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070806.121216.

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A prevailing view exists in the literature which suggests that macroalgae growing in slow-flow environments (<4 cm s⁻�) are less productive because of "mass-transfer" limitation compared to fast-flow environments. Macroalgae in slow-flow environments are thought to have thicker diffusion boundary-layers which limit the flux of essential molecules to and from the algal thallus. However nutrient demand of a macroalga can also influence nutrient flux. The main objective of this research was to determine the relative importance of physical (mainstream velocity) and physiological (nutrient demand) factors influencing the growth rate of Adamsiella chauvinii, a small (<20 cm) red algal species, that grows within the benthic boundary-layer in a soft sediment habitat. To establish the influence of water velocity, the growth rate of A. chauvinii was measured in situ each month (March 2003 to March 2004) at three sites with varying degrees of water velocity (slow, intermediate and fast) at which all other environmental parameters (photon flux density, seawater temperature and nutrients) were similar. To determine the metabolic demand and nutrient uptake rate of A. chauvinii, the internal nutrient status (C:N, soluble tissue nitrate, ammonium and phosphate), uptake kinetics (V[max] and K[s]) and nutrient uptake rate at a range of mainstream velocities were also determined on a seasonal basis. The hydrodynamic environment around A. chauvinii canopies was characterised in situ and compared with controlled laboratory experiments. Growth rates of Adamsiella chauvinii thalli at the slow-flow site were significantly lower in winter (June) to summer (February) than the intermediate- and fast-flow sites, while in autumn growth rates were similar between sites. However, A. chauvinii at the slow-flow site had similar or higher tissue N content compared to thalli at the other two sites during winter, spring and summer suggesting that growth rates of A. chauvinii were not mass-transfer limited. Nitrogen uptake rates of A. chauvinii were similar between sites in summer and winter, however uptake rates were lower in summer compared to winter even though thalli were nitrogen limited in summer. Water velocity had no effect on nitrate uptake in either summer or winter and uptake of ammonium increased with increasing water velocity during summer only. Two hydrodynamically different environments were distinguished over a canopy of A. chauvinii, with both the laboratory and field velocity profiles in good agreement with each other. In the top half of the canopy, the Turbulent Kinetic Energy (TKE) and Reynolds stresses were greatest while in the bottom half of the canopy flow rates were less than 90 % of mainstream velocity (< 1 cm s⁻�). When considered together, the influence of water velocity on the growth rates of A. chauvinii was not completely clear. Results suggest that mainstream velocity had little influence on nutrient availability to A. chauvinii because of the unique hydrodynamic environment created by the canopy. Nutrients, especially ammonium and phosphate, derived from the sediment and invertebrates, may provide enough nitrogen and phosphate to saturate the metabolic demand of Adamsiella chauvinii, consequently, A. chauvinii is well adapted to this soft-sediment environment.

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42

Meynier, Laureline. "Feeding ecology of the New Zealand sea lion (Phocarctos hookeri) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor Philosophy in Zoology at Massey University, Palmerston North, New Zealand." Massey University, 2009. http://hdl.handle.net/10179/901.

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The New Zealand (NZ) sea lion Phocarctos hookeri is the only pinniped endemic to NZ with a population of approximately 12,000 individuals. Its breeding range is currently restricted to NZ sub-Antarctic islands, and it has failed to recolonise its pristine distribution around the NZ main islands despite its protection since 1881. The current hypothesis is that the population growth of this pinniped is limited by the distribution of suitable prey on the Auckland Islands (50°30'S, 166°E) shelf, and by the direct and indirect pressure exerted by the arrow squid Nototodarus sloani fishery. However, this hypothesis has not been fully tested to date as there has been limited information on the diet of the NZ sea lion and their potential prey. The objective of this thesis is to analyse the diet of NZ sea lions over several years with particular emphasis on the most reproductively important segment of the population: lactating females. This thesis provides the first quantification by percentage mass of the diet of NZ sea lion using a combination of stomach content analysis, qualitative fatty acid (FA) analysis, and quantitative FA signature analysis (QFASA). Stomach contents and blubber FAs were analysed from 121 individuals incidentally caught (by-caught) in the southern arrow squid fishery from the years 1997 to 2006. The blubber FAs of 78 freeranging lactating females captured at Enderby Island, Auckland Islands, were also examined during January and February of 2000 to 2005. Data obtained from both stomach analysis and QFASA indicate that arrow squid, rattails Macrouridae, hoki Macruronus novaezelandiae and red cod Pseudophycis bachus are key prey species for NZ sea lions in the Auckland Islands region. Because these prey species live mostly at depths greater than 200 m, lactating females must undertake long foraging trips and dive regularly to greater depths than other sea lion species. Data from QFASA indicates that this foraging pattern is conducted over an extended period through the summer and autumn. The daily food requirement of a lactating female was estimated by a simple energetic model to be greater than 20% of its body mass. During years of low arrow squid recruitment such as 1999 and 2001, the amounts of squid required by the NZ sea lion population may have been similar to the amount harvested by the fishery, suggesting that resource competition is likely to occur between the arrow squid fishery and NZ sea lions in years of low squid abundance. Half of the fishing activity of the southern squid fishery occurs in the north of the Auckland Islands shelf where NZ sea lions forage, leading to incidental captures every year. This research emphasises that management of the NZ sea lion must not only consider the direct interactions with the arrow squid fishery, but also the likelihood of food resource competition between the fishery and NZ sea lions.

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Memory, Andrew Edmund. "What Factors Influence the Success of Senecio (Asteraceae) in Canterbury, New Zealand? A Phylogenetic and Ecological Study." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/7468.

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Abstract Senecio is one of the largest genera in the Asteraceae family with 28 Senecio species in New Zealand and over 1200 species worldwide. Native Senecio in the Canterbury region are typically naturally uncommon and exhibit extreme fluctuations in population size. Contrary to native Senecio, exotic Senecio in the Canterbury region are thriving. Why some exotic species thrive in a novel environment while native species decline has been an area of intense study since the era of Darwin. However, despite extensive study, we are still unsure about the underlying mechanisms of this phenomenon. This thesis looks at several hypotheses that have been proposed to explain differences in success between native and exotic species including four that have been frequently mentioned in the literature: phylogenetics, natural enemy release and biotic resistance, allopolyploidy and habitat modification. In order to determine if phylogenetic relatedness influences the abundance and distribution of Senecio species in Canterbury, DNA phylogenies of New Zealand’s Senecio were constructed using nuclear (ITS, ETS) and plastid (trnL, trnL-F and psbA-trnH) DNA sequences. The resulting cladograms were used to determine the areas of origin of New Zealand’s Senecio lineages, the identity of their closest relatives and lineages and species that are of allopolyploid origin. The data provided by the phylogenetic analyses was to provide context for analyses of ecological data of 86 native and exotic Senecio populations from the Canterbury region. My results indicate that phylogenetic relatedness is a poor predictor of the amount of folivory experienced by Senecio, although some natural enemies of native and exotic Senecio displayed a positive preference for Senecio depending on their clade. The strongest effects on Senecio and the occurrences of their natural enemies came from the surrounding land use which influenced the amount of folivory and the abundances of natural enemies on Senecio. Enemy release and biotic resistance were land use specific within Canterbury and by themselves cannot explain the variance in folivory when applied to a landscape scale. According to my results, the biggest factor influencing Senecio folivory, abundance and distribution in the Canterbury region is change in the surrounding land use.

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Jay, Grace Mairi M. "Symbolic order and material agency: A cultural ecology of native forest remnants on Waikato dairy farms." The University of Waikato, 2004. http://hdl.handle.net/10289/2603.

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Loss of native biological diversity is a world-wide problem of growing international concern. One of the main causes of native biodiversity loss is destruction and degradation of native habitat through land development for agriculture. The Waikato region is an example of the destruction and degradation of native habitat in association with the development and intensification of farming, including dairy farming. This thesis explores cultural reasons for the loss of native forest in the Waikato region, and reasons why fragments of native forest remain. The research involves a participant observation study of 'typical' dairy farm families for 9 months of the dairy year, in-depth interviews of dairy farmers who have protected a significant proportion of their land for conservation of native habitat, a questionnaire of dairy farmers, and an examination of dairy farm magazines and other literature to identify the values and attitudes that motivate dairy farmers in relation to land management and protection of native habitat. The title of the thesis suggests two elements that are important for understanding the loss and persistence of native forest in Waikato's farmed landscapes. Symbolic reason refers to the values, attitudes and perceptions of farmers that derive from socio-political and economic forces which encourage productivist practises that leave little opportunity for native forest to survive. Material agency refers to the local circumstances of particular farms and individual people which enable native forest to persist. The thesis argues that persistence of native forest depends on the idiosyncrasies of material circumstance in the face of relentless pressure to transform the production landscape for economic purposes. The thesis concludes with a suggestion that policies to assist survival of native habitat in farmed landscapes need to include ones that encourage the odds in favour of fortuitous circumstance. In the face of globalised economic pressures, policies for conservation of native biodiversity need to involve a 'portfolio' of measures that apply to individual landowners and the wider rural community by recognising, assisting and rewarding management for non-production values.

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Calder, Keith Wallace. "A LEEP forward : biodiversity futures for New Zealand : a thesis in partial fulfilment of the requirements for the Master of Resource and Environmental Planning at Massey University, Palmerston North, New Zealand." Massey University, 2007. http://hdl.handle.net/10179/741.

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Loss of indigenous biodiversity continues in New Zealand. Despite admirable goals in the NZBS 2000 to the contrary, efforts at improved biodiversity conservation have been insufficient to halt loss of significant amounts of indigenous forest and wildlife habitat. Increasing numbers of native species are moving towards critically endangered and extinction. Whatever we are doing in New Zealand, it is not effective enough. The aim of this study is to firstly identify factors contributing to the failure, “to halt the decline of indigenous biodiversity” in New Zealand and to then consider opportunities to overcome these barriers. In considering opportunities, this study then reviews the emerging discipline of landscape ecology as an answer to, at least, some of those factors and the recurring calls from New Zealand ecologists for a more integrated and holistic approach to biodiversity conservation. Recent advances in the planning framework and particularly provisions for biodiversity conservation in England are explored as a model of practical application of landscape ecological principles to land-use planning. From this review, the study proposes a new ‘LEEP’ model for strategic biodiversity conservation that produces a regional-scale spatial conservation map and accompanying policy and implementation guide. Together they provide an integrated and holistic approach to restoring or creating functional landscapes that also recognises and provides for human activities and development. Application of the LEEP model is demonstrated through a case study of the Wellington region. Benefits and potential uses of the map and policy outputs are canvassed. Interviews with leading New Zealand and international ecologists provide an assessment of the current status of landscape ecology and interviewees also act as an expert ‘test panel’ against which the Wellington maps and guides produced from the ‘LEEP’ model are assessed. Finally, suggestions are provided for development of the new model and future research needs towards fuller and more effective implementation of this approach to biodiversity conservation in the New Zealand context.

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Brown, Logan Arthur. "Habitat determinants and predatory interactions of the endemic freshwater crayfish (koura, Paranephrops planifrons) in the lower North Island, New Zealand : a thesis presented in partial fulfillment of the requirements for the degree of Masters of Science in Ecology at Massey University, Palmerston North, New Zealand." Massey University, 2009. http://hdl.handle.net/10179/1168.

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A study in the Lower North Island located Parenephrops planifrons (koura) at 73 sites out of 104 sites visited (appendix 1). There was a significant difference in habitat variables between the sites which had koura present and those where they were absent. Examples of sites are shown in Appendix 3. Habitat variables important for classifying koura habitat included riparian cover, predators, winter equilibrium temperature and presence of in-stream habitat in the form of vegetation, litter cover and the stream sequence composition. Regression trees built could accurately describe the data but the kappa statistic was low.

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Webb, J. A. "A study of the seed ecology of two species of kowhai, Sophora microphylla and Sophora prostrata in Canterbury, New Zealand." Thesis, University of Canterbury. Botany, 1993. http://hdl.handle.net/10092/8371.

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The seed ecology of Sophora microphylla (common kowhai) and to a lesser extent Sophora prostrata (prostrate kowhai) from two Canterbury sites was studied. The aspects of the seed ecology examined were firstly, immature germination, embryo maturity and seed predation in S. microphylla followed by a study of the seed banks, seed fall, seed dispersal, the influences of temperature and light on germination and early growth, and natural mechanisms employed for the scarification of the seed coat in both S. microphylla and S. prostrata. Germination experiments revealed that S. microphylla seeds can germinate when they are immature and that embryo maturity is achieved in most seeds at around 16 weeks of age, although some mature in only 12 weeks. The only significant predator of S. microphylla seed was the larvae of the moth Stathmopoda aposema, which began to predate the seeds at about 8 weeks of age and continued to predate them from this time on. It was found that predation by this organism accounted for the death of about 28% of seeds in the population of trees studied in the 1991-92 year, although annual fluctuations probably occur. Wind was found to be the principle mechanism of seed removal from the trees of both S. microphylla and S. prostrata and the main, if not the only, dispersal mechanism in S. prostrata. Although wind does play a role in the short distance dispersal of S. microphylla seeds (particularly the whole fruit or pod) the chief mechanism of long distance dispersal in this species is water. S. microphylla possesses both buoyant (up to 27%) and non-buoyant seeds, attributable to the density of its embryo, which is thought to aid the long distance dispersal process. It was found that S. microphylla possessed two types of seed banks one on the tree (resulting from the retention of previous seasons seed) and the other in the soil. The soil seed bank was found to be extensive and deep although most seeds were contained in the top 10cm of the soil profiles dug. S. prostrata seemed to have no long-term seed banks as such although many seeds are assimilated into the humus layer beneath parent plants before being lost downslope or germinating, indicating a very temporary soil seed bank at most. The seeds of both S. microphylla and S. prostrata were sensitive to temperature when germinating and have an optimum germinating range of about 10-20°C. As expected there was no obvious sensitivity to light during the germination of either species and most seeds established more successfully after burial (lightless conditions). However, the light intensity appeared to affect young seedlings with both species showing a distinct etiolation pattern. The scarification of seeds in nature appeared to be different for each species. For S. microphylla, scarification of the seed coat did occur in the soil and this was supported by the discovery of germinated and imbibed seeds there. But how this happens is still not clear. It is thought that it may be a result of very gradual microbial breakdown of the micropyle, or influences from other soil organisms. It is also possible that many seeds are scarified in river systems by alluvium in river beds, however experiments showed that many seeds particularly those which are not buoyant may be destroyed in the riverbed environment. Mature S. prostrata seeds when relatively young appeared to have soft seed coats, and at this stage seeds would imbibe and germinate without scarification. As seeds get progressively older however, the seed coats harden and scarification was necessary before germination could take place. After hardening, breakage of the seed coat was thought to occur due to abrasion of soil particles as the seeds move downslope under the influence of gravity or by similar mechanisms to S. microphylla after assimilation into the soil.

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48

Soliman, Nabil Zaki Gadalla. "Nutrient dynamics at Matapouri Estuary, Northern New Zealand thesis submitted in (partial) fulfilment of the degree of Master of Applied Science, Auckland University of Technology, June 2004." Full thesis. Abstract, 2004.

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49

Bray, Jonathan Peter. "The ecology of algal assemblages across a gradient of acid mine drainage stress on the West Coast, South Island, New Zealand." Thesis, University of Canterbury. Biological Sciences, 2007. http://hdl.handle.net/10092/1492.

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Physicochemical factors, algal diversity, taxonomic composition and standing crop were investigated across a broad gradient of AMD stress in streams and rivers. 52 sites were surveyed in the vicinity of Greymouth, Reefton, Westport and Blackball, on the West Coast, South Island. Seven sites in the Reefton area were sampled from April 2006 - February 2007 to establish changes over time in benthic algal communities of AMD and reference streams. Longitudinal change and ecosystem recovery were also investigated by sampling eight sites down Devils Creek, Reefton, and two of its tributaries. AMD has negative impacts on algal diversity, generally increases the dominance of certain taxa and, where metal oxide deposition or hydraulic disturbance are not great, can lead to algal proliferations. These proliferations were chlorophyte dominated, predominantly by filamentous Klebsormidium acidophilum. From the general survey a total of 15 taxa were identified from the most severely impacted sites (pH <3.6), which included both acidophiles and acidotolerant algae. Multivariate analyses strongly suggest that pH was the dominant factor controlling taxonomic occurrence of diatoms, macroalgae and the structure of the total assemblage. Other factors such as conductivity, metal oxide deposition, temperature, depth, month, geographic location and altitude were also important. Algal communities changed over time and this became more marked as AMD impact decreased. This was presumably due to AMD stressors reducing diversity, and thus the available scope for assemblage change. Longitudinal differences in assemblage structure within Devils Creek appeared to be in response to dilution of AMD in upper reaches and to changes in natural physical features such as gradient in mid and lower reaches. After a distance of 7.2 km the physicochemical effects of AMD and suspended clay inputs were minimal. At this site and at several previous sites, the assemblage exhibited a degree of recovery towards that found at unimpacted sites. A range of algae found in the broad scale-survey are potentially useful 'sensitive' indicators. These included: Heteroleibleinia purpurascens; Achnanthes oblongella; Oedogonium sp. and Spirogyra sp. In contrast: Euglena mutabilis; Navicula cincta; K. acidophilum; Microspora quadrata and Microthamnion kuetzingianum may be useful 'tolerance' indicators. These data show that AMD has a range of negative impacts on algae, and algae may be a useful tool for monitoring these impacts in West Coast streams.

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Wood, Jamie Russell, and n/a. "Pre-settlement paleoecology of Central Otago�s semi-arid lowlands, with emphasis on the pre-settlement role of avian herbivory in South Island dryland ecosystems, New Zealand." University of Otago. Department of Geology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080211.142212.

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The vegetation communities that existed in the semi-arid intermontane basins and gorges of Central Otago prior to human settlement ~750 years B.P. are poorly understood. This is because of a lack of fossil evidence and complex restructuring by anthropogenic factors, especially increased fire frequency, and more recently mammalian grazing. There is also little information regarding the effect of the lost fauna on maintaining and structuring presettlement communities, both in Central Otago and throughout the eastern South Island dryland zone. This study aims to provide a clearer understanding of the functioning of pre-settlement ecosystems in dryland Central Otago, particularly the role of the largest vertebrate herbivores, the moa (Aves: Dinornithiformes), and to explore the implications of the extinct fauna for land conservation management across New Zealand. Late Pleistocene and Holocene vegetation communities of the Central Otago lowlands were reconstructed from plant macrofossils, including seeds, leaves, and wood, excavated from rockshelter, cave, and swamp deposits throughout the region. The macrofossils represent three main vegetation types: late Pleistocene to mid (late?) Holocene basin floor wetland herb associations, Olearia-shrublands surrounding these wetlands, and mid to late Holocene open scrubland and woodland in gorges and on low altitude slopes, dominated by filiramulate Olearia, Coprosma, and Corokia, with abundant lianes (Muehlenbeckia spp. and Rubus spp.) and understorey herbs. Many native tree and shrub species that are presently widespread in the Central Otago lowlands were rare or absent prior to anthropogenic fires (e.g. Discaria toumatou, Kunzea ericoides, Leptospermum scoparium). Other tree and shrub species once present are now extinct in the region (e.g. Coprosma obconica, Plagianthus regius, Pseudopanax ferox). The loss of these indigenous woody vegetation communities was a major factor contributing to the extirpation of many small bird species, and undoubtedly also reptile and invertebrate species, from the region. Plant macrofossils from rockshelters included remains of bird nests, identifiable by desiccated feathers and eggshell amongst them. These macrofossils include the first described plant remains from the nests of moa, which were constructed from a shallow bed of twigs of locally available shrubs and lianes. Many of the twigs are 25-30 mm in length and show evidence of having been clipped by moa bills. Desiccated coprolites, mostly of moa, but also specimens attributed to Finsch�s duck (Chenonetta finschi) and red-crowned parakeet (Cyanoramphus novaezelandiae), were recovered from rockshelter excavations. Moa species associated with a sample of coprolites were identified using ancient DNA analysis, and plant macrofossils from these were examined, together with previously unexamined moa gizzard content samples excavated from mires in the eastern South Island dryland zone. The results indicate that, in addition to previously reported browsing, upland moa (Megalapteryx didinus) and heavy-footed moa (Pachyornis elephantopus) also functioned as grazers, and seeds in their coprolites are dominantly of low shrubs and ground-cover herbs. Of particular interest was the higher than expected frequency of seeds from the currently rare and threatened 'spring annual' herbs; Ceratocephala pungens and Myosurus minimus subsp. novae-zelandiae (Ranunculaceae), suggesting further research on potential ecological relationships between moa and these plants would be worthwhile. The results of this study have provided a baseline for future conservation and restoration projects in the Central Otago lowlands.

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Dissertations / Theses on the topic 'New Zealand ecology'

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