Academic literature on the topic 'Fields of Research – 270000 Biological Sciences – 270700 Ecology and Evolution'

The population dynamics of juvenile snapper, Pagrus auratus, were investigated in the Hauraki Gulf, north-eastern New Zealand, between 1982 and 1990. Attention focused on age and growth, temporal and spatial variation in abundance, and recruitment. Daily increment formation was validated in the sagittae of snapper up to about 160 days old. Increment width varied with time of year, and snapper age, and increments were not resolvable with a light microscope during winter. Increment counts inside a prominent metamorphic mark showed that larval duration was 18-32 days, and was inversely related to water temperature. Spawning dates were back-calculated from increment counts in settled juveniles, and ranged from September to March with a peak in November-January. The onset of spawning was temperature dependent. Fast-growing snapper had smaller sagittae than slow-growing snapper, indicating an uncoupling of otolith and somatic growth. Snapper gonads differentiated first as ovaries during the second year of life, and then some juveniles changed sex to become males during their third year. Sex change occurred before maturity, so snapper are functionally gonochoristic. Growth was slow during the larval phase, but increased rapidly after metamorphosis to about 0.6-0.9 mm.day-1. From the first winter, growth followed a well-defined annual cycle, with little or no growth during winter, and linear growth of 0.16-0.43 mm.day-1 during spring-autumn for 0+/1+ and 1+/2+ snapper. Snapper grew faster at higher temperatures. Trawl catch rates were affected by numerous gear and environmental factors, but probably provided reasonable estimates of snapper relative abundance. Recommendations are made for improving snapper trawl survey procedures. There was a strong annual abundance cycle in the Kawau region, peaking in spring, and declining to a minimum in winter. Snapper were patchily distributed at a spatial scale of 1-2 km, probably because of preference for specific micro-habitats. Year class strength of 1+ snapper varied 17-fold over seven years, and was strongly positively correlated with autumn sea surface temperature during the 0+ year. The strengths of the 1991 and 1992 year classes are predicted to be below average, and extremely weak, respectively.

This thesis develops a quantitative cladistic approach to panbiogeography. Algorithms for constructing and comparing area cladograms are developed and implemented in a computer program. Examples of the use of this software are described. The principle results of this thesis are: (1) The description of algorithms for implementing Nelson and Platnick's (1981) methods for constructing area cladograms. These algorithms have been incorporated into a computer program. (2) Zandee and Roos' (1987) methods based on "component-compatibility" are shown to be flawed. (3) Recent criticisms of Nelson and Platnick's methods by E. O. Wiley are rebutted. (4) A quantitative reanalysis of Hafner and Nadler's (1988) allozyme data for gophers and their parasitic lice illustrates the utility of information on timing of speciation events in interpreting apparent incongruence between host and parasite cladograms. In addition the thesis contains a survey of some current themes in biogeography, a reply to criticisms of my earlier work on track analysis, and an application of bootstrap and consensus methods to place confidence limits on estimates of cladograms.

Growth, development and behaviour were examined in artificially reared larval Pagrus auratus and Forsterygion varium, from the time of hatching. Yolk-sac larval P.auratus hatched at a small size (2.00mm SL), without functional eyes, mouth or digestive tract, and for three days spent long periods at rest. Growth was initially rapid but slowed by 3 days as yolk reserves neared depletion. By days 4-5, the mouth had opened, eyes were functional, yolk was depleted, and a rudimentary gut had formed. Larvae were now able to maintain a horizontal swimming mode and were actively searching for and attacking prey. First feeding was observed in some larvae. Growth was retarded during the transition from endogenous to exogenous nutrition and then increased as feeding proficiency improved. Yolk-sac F.varium hatched at a larger size (4.78mm SL), with functional eyes and jaws. Larvae were able to maintain a horizontal swimming mode from hatching. First feeding was observed from the first day after hatching. F.varium larvae grew steadily from the time of hatching. Ocular morphology was examined in larval, juvenile and adult P.auratus and F.varium. There was a 96 fold increase in eye size, from 0.23mm diameter in a 4 day old larval P.auratus (3.4mm SL) to a maximum diameter of 22mm in an adult of 333mm body length. F.varium displayed a 26 fold increase in eye size, from 0.28mm diameter in the smallest larva (5.00mm SL) to a maximum eye diameter of 7.2mm in a 11gmm long adult. Larval fish had pure cone retinae, however putative rod precursor cells were present from hatching in F.varium and from 18 days in P.auratus. Juvenile and adult fish had duplex retinae with cones arranged in a square mosaic in which 4 twin cones surround a central single cone. Hypertrophy of cone ellipsoids with increasing eye size, resulted in maintenance of a closely packed array in fishes of all sizes. The appearance of retinomotor movements was coincident with the development of a duplex retina in both species. Theoretical spatial acuity (calculated as a function of cone spacing and focal length of the lens) was poor in the smallest larval fish (2° 1' and 1° 8' minimum separable angle in 4 and 1 day old P.auratus and F.varium respectively) but improved to asymptotic values in adults (3'- 4', and 9' in P.auratus and F.varium respectively). Behavioural acuity (determined using the optokinetic response) of 4 day old larval P.auratus (37° 30') and 1 day old F.varium (29°) was very much lower than histological estimates. Behavioural acuity improved to 8° 8' in 16 day old P.auratus and 4° 18' in 14 day old F.varium, but did not attain theoretical estimates for fish of that size (55' and 54'). A rudimentary retractor lentis muscle was first apparent in larval fish 1 week after hatching, and was coincident with the formation of a posterior lental space. Presumably larval fish eyes were incapable of accomodative lens movements until this time. A relative measure of Matthiessen's ratio (distance from lens centre to boundary of the pigmented retinal epithelium/lens radius) measured histologically, decreased from 4.2 and 2.7 in 3 day old P.auratus and newly hatched F.varium, to 2.2 and 2.3 in larvae 22 and 16 days of age respectively. This suggests that growth of the retina and lens were not symmetrical in the eyes of very small larval fish. If Matthiessen's ratio holds for little eyes, then they will initially be strongly myopic. This may account in part for the mismatch between behavioural and theoretical acuity. Perceptive distances of first feeding larval P.auratus and F.varium, estimated for prey items equal in dimensions to maximum jaw widths, were very small (0.2mm and 0.4mm for prey 0.15mm and 0.2mm in size respectively), but increased with increasing body size to 2.1mm and 4.0mm for prey 0.3mm in size, at 16 and 14 days of age respectively. These data have implications for larval feeding in the wild.

The sap beetle genus Carpophilus Stephens (Coleoptera: Nitidulidae) is a large genus consisting of over 200 species and are found worldwide. Several species are important pests of crops and stored products, and are frequently intercepted as part of biosecurity operations. The genus is poorly known taxonomically, and there are several species groups that are challenging to identify by morphological methods. In particular, two species found across the Pacific, C. maculatus Murray and C. oculatus Murray are frequently confused with each other. These two species are similar in size and colour, but differ primarily by the shape of the colour pattern on their elytra. However, this colour pattern is highly variable within both species, leading to ambiguity in the indentification of these species. Within C. oculatus, three subspecies have been described based on differences in the male genitalia and pronotal punctation: C. o. oculatus and C. o. gilloglyi Dobson are distributed widely across the Pacific, while C. o. cheesmani Dobson is known only from Vanuatu. A search of literature records and specimen collections revealed 32 species of Carpophilus recorded from the Pacific region. In addition there remain several unidentified specimens representing at least four species, two of which will be described subsequent to this research. A number of species recorded in the literature may have been misidentified, and these require further field collections and inspection of museum specimens to confirm their presence in the Pacific. To test the validity of the subspecies of C. oculatus, and its distinctiveness from C. maculatus, a phylogeny of available specimens of Carpophilus was inferred from one mitochondrial gene (cytochrome c oxidase subunit I (COI)), and two nuclear genes (28S ribsomal RNA (28S) and the internal transcribed spacer 2 (ITS2)). These data show large genetic distances between the three subspecies of C. oculatus of 7-12%. Given these distances are similar to those between other species in the genus, this indicates these subspecies may be elevated to full species. The data also consistently support a monophyletic relationship between C. o. oculatus and C. o. gilloglyi. Nuclear genes also support C. o. cheesmani as part of a clade with the other subspecies, but these relationships are unresolved in COI. Carpophilus maculatus was not supported as being the sister taxon of the C. o. oculatus and C. o. gilloglyi clade. Other relationships within Carpophilus were unresolved, possibly due to a combination of incomplete taxon sampling, and saturation of substitutions within the COI gene. Phylogeographic analysis of specimens collected from several localities within the range of C. oculatus showed that, with only one exception, there were no shared haplotypes between archipelagoes. This result suggests it may be possible to determine the provenence of intercepted specimens, providing further information regarding potential invasion pathways. A degree of geographic structuring was also present within C. o. gilloglyi, being separated into a western clade found in Fiji and Rotuma and an eastern clade distributed from the Kermadec Islands and Tonga to French Polynesia. This separation was most profound in COI data, with a mean pairwise distance between the clades of 7%. ITS2 data also demonstrates a degree of differentiation between the two clades, based on differences in the insertions and deletions between the clades. The variability in the shape and colour of the elytral pattern of C. oculatus was also investigated. Colour was quantified using a method based on Red-Green-Blue (RGB) colour values derived from digital photographs, while an outline analysis of the elytral pattern was conducted using elliptic Fourier analysis (EFA). Principal Components Analysis of the RGB values and EFA coefficients showed no clear separation between subspecies, nor were any trends correlated with host fruit or collection localities. Variation at all levels and all measures studied in this thesis show that this geographic region and this genus of beetles offer intruiging insights into speciation, biogeography and biological invasions. There is much scope for further research on the causes and consequences of this variation and the lives of these interesting insects.

Honeybees (Apis mellifera) are important pollinators of many plant species and are employed globally for crop and honey production. However, little is known about the effects of this species on native pollinator and plant species in areas to which they have been introduced; and previous research has not been able to reach a general consensus as to the type of impact honeybees have on pollination systems. In addition to the effects of exotic pollinators, the loss and fragmentation of natural habitats is also of major concern to the continuing diversity of pollinators and plant populations. Here, the impact of honeybee density on other pollinator guilds, and levels of remaining pollen and nectar standing crop among 18 patches of the New Zealand native shrub – manuka (Leptospermum scoparium) is examined at three different regions within the North Island. The same sites were also used to test the reproductive capabilities of manuka and subsequent pollen limitation among patches. A further 11 sites were utilised to examine biodiversity via intercept and pitfall traps within manuka patches, and the patch variables driving taxa composition. Large fly (Diptera = 5 mm) abundance was negatively correlated with honeybee abundance and instances of physical disturbance of large flies by honeybees were observed. There was no significant correlation between honeybee abundance and other pollinator guilds. Nectar was a limiting resource for both honeybees and large flies, whereas, pollen was not a limiting resource among any of the major pollinating insect guilds. Pollination treatments revealed that manuka is partially self-compatible, but relies more heavily on cross pollination for higher yields of capsule and seed set. Pollen limitation did not occur significantly at any of the sites. A total of 159 Coleoptera, 125 Diptera, 131 Hymenoptera morphospecies, and 50 other groups of taxa from various orders were collected among sites. Invertebrate richness was higher at lower altitudes and litter invertebrate richness was significantly higher with an increase in the proportion of manuka cover. There were distinct differences in taxa composition between the three regions, with plant community composition and altitude the most significant factors. Patch size also played a part, but a lack of overall variation in patch sizes may understate the effect this has on insect composition. Overall, honeybees are competing for nectar resources and displacing large flies as a consequence; however, capsule and seed set among manuka patches did not significantly suffer as a consequence. Regional variation in patch characteristics such as altitude, plant community composition, patch size, proportion manuka cover, and plant evenness appear to be influencing insect composition found within manuka patches to varying degrees. Further investigation into the impact of patch size and patch connectivity is also warranted.

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.

Baited pitfall traps were used to sample the lizard fauna at Birdlings Flat on Kaitorete Spit, Canterbury. Four species had been recorded previously from this area; Leiolopisma maccanni Patterson and Daugherty, Leiolopisma nigriplantare polychroma Patterson and Daugherty, Leiolopisma lineoocellatum (Dumeril and Dumeril) and Hoplodactylus maculatus (Gray). Three of these species (L. maccanni, L. n. polychroma and H. maculatus) were captured during the course of the study. The aim of this present study was to examine the nature of the ecological relationship among these three species at Birdlings Flat. Capture data indicated that L. maccanni was almost entirely confined to the dunelands while L. n. polychroma was associated exclusively with shrublands on old dune ridges behind the sand dunes. H. maculatus' distribution encompassed both of these major habitats. Separation on the basis of habitat was thought to be the most important niche variable for these two diurnal skinks. There was some temporal separation in activity of these two species, with L. maccanni active earlier in the day than L. n. polychroma. However, there was a high degree of overlap in the activity periods of these two species. Temporal differentiation between the nocturnal gecko H. maculatus and the two diurnal skinks is thought to be an important means by which these species coexist. The most common prey items consumed by all three species were Diptera, Araneae, C. propinqua seeds, Hemiptera, unidentified arthropod eggs, Coleoptera and Hymenoptera. Dietary differences between the two skink species were apparent although these differences appeared to be related to the preferred habitats of the respective species. Density estimates for L. maccanni varied between 1050/ha and 1850/ha while L. n. polychroma density varied between 200/ha and 400/ha. The density of H. maculatus was not calculated but appeared to be intermediate to the density of the two skink species. The apparent disappearance of L. lineoocellatum from an area where they were once relatively common is cause for concern. There is no obvious reason for this decline although it may be related to the combined impacts of predation, collection and habitat disturbance.

Various aspects of metabolism and physiology were investigated during the ontogeny of yellowtail kingfish (Seriola lalandi), a fish of growing aquaculture importance in both New Zealand and other countries. Incubation experiments between 18-24°C showed that developing eggs and larvae were heavily influenced by temperature. It appeared that at warmer temperatures larvae hatched smaller but grew on the yolk sac, whereas at cooler temperatures larvae grew inside the chorion. Oxygen consumption data supported this, with a negative correlation found between total embryonic oxygen consumption and temperature. A mechanism was proposed to explain the differential effect of temperature on ontogeny and growth. Like other marine fish with pelagic eggs, yellowtail kingfish were found to be heavily reliant on free amino acids as a source of energy. At 23°C the pattern of substrate utilisation in eggs was considerably different from that at 17-21°C, indicating that 23°C exceeded the tolerance for normal development. Inter-individual aggression by large individuals was associated with the development of size heterogeneity in juveniles. Although this aggression also affected the survival of smaller juveniles, it was not the primary agent of much of the mortality that occurs during this phase, as many of these individuals were on a degenerate developmental trajectory. Yellowtail kingfish fingerlings used for ongrowing were robust to the stressors imposed by live transport. The ontogenetic development of metabolic rate from 0.6 mg-2.2 kg did not follow the same scaling exponent as that observed for mammalian models of allometry, and has implications for interspecific studies of mass-dependent metabolism.

The impact of no-take marine reserves on spiny lobster, Jasus edwardsii, populations and the adjacent lobster fishery was assessed in a study that determined: the response of lobster populations to protection, if lobsters within marine reserves moved out into the surrounding fishery, examined the behavioural characteristic of lobsters that contributed to their recovery and spillover, and contrasted catch characteristics around a north-east New Zealand marine reserve with 2 unprotected sites. Surveys of 4 no-take marine reserves of different ages and 4 unprotected control sites confirmed that J. edwardsii increase in mean size and abundance within protected areas. Total lobster density was estimated to increase by 6.1% per year of protection. The relationship between age of reserve and the density of lobsters above the legal size limit (>100 mm carapace length) was complicated by depth related interactions between reserves, due to seasonal changes in the depth distribution of lobsters and differences in the timing of surveys among locations. However, density increases in legal sized lobsters were greater than those of the overall population. Mean size of protected lobsters increased in a non-linear fashion, reflecting the asymptotic growth characteristics of the species. Mean carapace length of lobsters increased by 11.24 mm after 3 years of protection and only by 16.25 mm after 2l years of protection. Corresponding increases in biomass (kg.500 m-2) and egg production (eggs.500 m-2) were estimated to be 7.4% and 6.6% respectively per year of protection. A tag recapture program indicated that the limited scale of movements and relatively high site fidelity of mature J. edwardsii aided the recovery of lobster populations in protected areas. Of 737 lobsters tagged in and around the Leigh Marine Reserve,212 were subsequently resighted. Seventy percent of resighted lobsters were relocated less than 250 m along the shore from their initial site after a mean period of liberty of 146 (se = 13.42) days. However, seasonal offshore movements took lobsters beyond the seaward boundary of the reserve where they were susceptible to capture. Of the 521 lobsters tagged on inshore reefs within the Leigh Marine Reserve. l.9% were caught over the seaward boundary by commercial fishers, and 14.4% of the 181 lobsters tagged over the seaward boundary were resighted on inshore reefs within the reserve. Movements into or out of the reserve across the longshore boundaries were also recorded for 7 out of the 27 lobsters moving further than 250 m along the shore. Acoustic tracking confirmed that J. edwardsii have a high site fidelity, with tracked lobsters spending a median of 84% of their time at their home site. Twenty one percent of the 26 lobsters fitted with acoustic tags never left their tagging site and, of those that did leave 56% eventually returned. Lobsters moved up to 3.1km away from their home sites but managed to find their way back after periods of 1 to 103 days away. Five lobsters had strong associations with two separate sites and made repeated movements between these alternate home sites. The straight line distance between alternate home sites ranged from 200 m to 1.3 km, and the period between visits to their primary or secondary home sites ranged from 1 to 93 days. Movement activity varied throughout the year, and seasonal patterns differed between males and females. Females displayed one peak in movement activity per year, around the time of larval release in September-October. Males displayed a summer peak centred on January, and a winter peak centred on July. The onset of high movement activity was often accompanied by a shift to deeper water and l0 of the 14 lobsters tracked for over 6 months spent periods away from the inshore reef system. Exposed groups of lobsters were observed aggregating in offshore areas of sand and low lying patch reef during the day. Offshore aggregations were observed over 7 months of the year and lobsters within the aggregations displayed behaviour consistent with the use of mutual defence. The sexual composition of the aggregations reflected seasonal patterns in male and female movement rates. Male J. edwardsii dominated the aggregations in winter and summer; times when peak feeding rates of males held in captivity were also recorded. Females dominated the offshore aggregations in September-October when larvae are released. Seven of the 26 lobsters fitted with acoustic tags moved over the boundaries of the Leigh Marine Reserve and Tawharanui Marine Park during offshore movements. Despite the fact that there is no fishing access to inshore reefs within the Leigh Marine Reserve, no significant difference was detected between the catch per unit effort (kg.trap haul-1) of lobsters caught around the reserve, nearby coastal Leigh or Little Barrier Island. However, catches around the marine reserve contained fewer (P=0.0009) but larger lobsters than at Little Barrier Island. The catch characteristics of lobsters from coastal Leigh were intermediate between the other two sites. As access to inshore reefs around the Leigh Marine Reserve was limited to a small area at either end of the reserve, traps tended to be set in offshore locations and the sexual composition of the total catch around the Leigh Marine Reserve reflected the seasonal movements of males and females into, and out, offshore areas. At coastal Leigh and Little Barrier Island the location of traps was not restricted and greater use was made of coastal fringing reefs. As a result the sexual composition of the catch at these locations did not reflect the movement of various components of the lobster population into and out of specific habitats or locations. Overall, the results of this study suggest that relatively small (~ 5 km2) no-take marine reserves increase lobster biomass and egg production, without adversely affecting catch rates in the surrounding fishery. Marine reserves may therefore represent a viable management tool, which if used in conjunction with other management regimes, could provide a more precautionary approach to the management of the J. edwardsii fishery at minimal cost to the industry.

The population biology and ecology of scallops in Greater Omaha Bay (a semi-oceanic bay) and Kawau Bay (a estuarine bay) was quantified by observation and experiment. Information was collected to extend the knowledge base on northern New Zealand scallop population dynamics, and for application to potential scallop enhancement in the region. Contagious scallop population organisation was found at all spatial scales examined, ranging from bay wide through to individual bed patchiness, down to the scale of inter-animal distances. Such clumping has strong implications for a range of population processes, including fishing susceptibility and fertilisation success. Monitoring of adults found two main spawning events to occur; in late October and in mid January. Changes in the gonado-somatic index (GSI) were well synchronised between individuals within populations. Subsequent monitoring of spat-fall in artificial collectors documented two main recruitment events, probably the outcomes of the two local spawning events. These spat-fall events occurred on collectors separated by 1Os of km. However, substantial density variations occurred between sites, indicating that local hydrodynamics may have played a significant role in modifying local spat-fall intensities. Smaller spat-fall events were also present between the two major events. The number of spat collected at a number of combinations of site and time were sufficient to support commercial spat catching operations, although problems were encountered with spat detaching at sizes too small to be retained by the collectors. In the 1993/94 summer a large algal bloom event completely eliminated scallop recruitment to collectors for the first three months of that season. Mass mortality events were a major contributor to overall benthic scallop population mortality. Probable causes included intensive scallop harvesting (commercial and recreational), a major storm episode, and a large algal bloom. These effectively eliminated scallop populations from Greater Omaha Bay. The adjacent Kawau Bay was not affected by any of these particular events, but populations there did not survive long after reaching adult sizes. Estimates of M (natural mortality) were higher for all scallop populations than have been previously documented in New Zealand studies. Growth trajectories were reasonably consistent in waters shallower than 19 m, but a progressive decline occurred in both maximal size reached and average growth rates with increasing depth after this point. Food limitation may have been the mechanism involved, which is likely to vary significantly for other locations depending on local environmental conditions. Average time to recruitment to the fishery (100 mm shell width) was three years for the shallower populations. A slight reduction in average size of adults at higher densities was found for some populations, indicating a possible density-dependent effect. Examination of a high density scallop bed found animals to display distinctive substratum preferences over small spatial scales, with higher abundances occurring on coarser materials such as shell gravel, marl and grit. Mud was not favoured as a habitat type. Movements of tagged animals at this location were spatially limited to within the particular habitat patch in which an individual was tagged and released, i.e. at a scale of 1s to 1Os of metres. No animals moved between adjacent patches of similar habitat (100 m scale). A B.A.C.I type experiment was undertaken to assess incidental mortality effects of commercial scallop dredging on undersize scallops, at the spatial scale of beds. Significant negative effects were quantified, with the number of undersize animals killed per legal animal harvested estimated at 1.7 and 2.8 : 1, depending on the size frequency structure of the fished bed. Modelling of likely improvements in the number of animals surviving at the end of fishing, given a reduction in the minimum legal size from 100 to 90 mm, indicated improvements of 20 to 41% of the original population remaining after fishing, depending on animal size and assumed dredge efficiencies, A 90 mm MLS has subsequently been adopted by the Coromandel Scallop Fishery. The results from this work provide detailed population based estimates of parameters required for successful management and optimal harvesting strategies of Hauraki Gulf scallop populations. The large variability in parameters such as mortality, and strong abundance correlations with habitat type, has strong implications for such activities. This work also provides essential information for the undertaking of locally based enhancement operations, such as the spatial and temporal magnitude and variability of spat-fall events, and growth rates with respect to habitat features (i.e. depth).