Tesi: "Banks Peninsula"

1

Parker, S. K. "The hydrogeology of the Diamond Harbour region, Banks Peninsula". Thesis, University of Canterbury. Geology, 1989. http://hdl.handle.net/10092/5501.

Testo completo

Abstract (sommario):

The study area comprises an area of about 40 km2 and includes the township of Diamond Harbour located on the sourthern side of Lyttelton Harbour. The area is broken up into two valley systems (Orton Bradley and Purau Valleys) separated by a gently northward dipping slope known as the Diamond Harbour ‘Dip-slope’. Pressure on a water reticulation pipeline due for repair or replacement, combined with an increasing population) formed the basis for this investigation. It was hoped that local groundwater resources could at least supplement the domestic supply coming from Lyttelton. Drill hole and geophysical information confirmed that the sediments that fill the lower Purau and Orton Bradley Valleys consist of river clays and silts, marine/estuarine muds and a number of gravel units. In the case of the Purau Valley two aquifers were located, a first probably representing an infilled river channel or channels immediately overlying volcanic bedrock (Lower Purau Aquifer), and a second river gravel unit which is saturated only within 200m of the coast (Upper Purau Aquifer). While no borehold data was available to confirm geophysical data interpretations for the Orton Bradley Valley, the indications are that a single river gravel unit exists, and that it is saturated near the coast. Pump test results for the Lower Purau Aquifer show that this aquifer has a transmissivity of 11.92m2/day and a storage coefficient of 3.87 x 10-4. Computer modelling indicated the Lower Purau Aquifer possesses two hydraulic boundaries 14 and 50m from the pumped bore I and this is consistent with the interpretation of the aquifer being an infilled river channel of approximately 64m width. Evidence suggests that the alluvial aquifers of both valleys are recharged from deep circulating groundwaters present in fractured bedrock aquifers located within the volcanic formations found in the area. Isotope and chemical evidence suggests that the alluvial and deep circulating groundwaters are similar in their relative concentrations of most ions, and have similar residence times of about 50 years. The deep and alluvial groundwaters are fit for domestic supply provided treatment is carried out for excessive concentrations of iron and manganese, and aeration to bring low pH values to within acceptable limits. An experiment on a known perennial High Altitude Spring indicates that the increased discharge seen following a rain event is composed almost entirely of 'old' stored water, and the increased flow is due to increa.sed pressure head following recharge of the aquifer system by meteoric waters. Superimposed on this event variability is a seasonal discharge variability related to seasonal rainfall patterns. An infiltration- 'head' /storage model is proposed to explain the behaviour of the High Altitude Springs of Diamond Harbour. Isotopic evidence suggests an exponential-piston flow model is consistent with observed results and this indicates the spring groundwaters have residence times of 10 to 25 years. An estimate of the safe yield from all available water resources in the Diamond Harbour area ranges from 660 to 1300m3/day, allowing for sufficient water to maintain acceptable river baseflows.

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Sanders, R. A. "Hydrogeological studies of springs in Akaroa County, Banks Peninsula". Thesis, University of Canterbury. Geology, 1986. http://hdl.handle.net/10092/5504.

Testo completo

Abstract (sommario):

Akaroa County, which is situated on the eroded remnant of the basaltic Akaroa Volcano, is developing as a tourist and recreational area, with consequent increasing demands on water supplies. Improved utilisation of the springwater resource of the area is a possible solution to these demands and this thesis develops hydrogeological models for the springs to assist in their future management. Methods used in this study include detailed hydrogeological mapping of two specific areas, isotope and chemical analyses of springwater, and spring discharge monitoring over a one year period. Groundwater discharge as springs and seeps is common in Akaroa County, with more than 200 springs mapped in the French Farm study area and 470 springs in Pigeon Bay Valley. Spring discharge may occur directly from defects in the basaltic lavas, but more commonly occurs through the surficial cover that mantles most of the area. Relatively impermeable beds (eg. tuff and unjointed lava) within the volcanic sequence are the dominant influence on spring distribution because of their perching effect. A “head”/storage groundwater model is proposed whereby water contained in heterogeneous lava "aquifers" is displaced to springs by infiltrating rainwater because of a pressure head applied to the irregularly shaped perched groundwater bodies. Most springs flow at less than 2.5 litres per minute and discharges of greater than 15 litres per minute are uncommon. All monitored springs show high discharge variability (1780% for one measured spring), with peak discharge occurring in winter and the lowest flows in autumn. The "Abattoir Spring" in the summit region shows rapid (within 24 hours) response to storm events with subsequent peak flows occurring 2 to 6 days later. Groundwater recharge is the result of infiltration of local precipitation, and the greatest potential for recharge occurs in the summit regions. Chemical quality of the springwaters is generally within the N.Z. Standards for Drinking Water, although nearly all samples show low pH values (pH = 6.0 to 7.3) and some show high iron and turbidity contents. Proposed utilisation of springs for water supply will require preliminary discharge monitoring. If excavation of the spring is employed to increase yield then water budget analysis of the recharge area should be undertaken so that safe yields are not exceeded. Reticulation systems should incorporate treatment facilities to counteract low pH, turbidity, or high iron content where these exceed Standards limits. Future study should include detailed water budget work to determine the magnitude of the groundwater resource of Akaroa County.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Hughes, Terrence Jon. "A detailed study of Banks Peninsula loess shear strength". Thesis, University of Canterbury. Geology, 2002. http://hdl.handle.net/10092/10021.

Testo completo

Abstract (sommario):

This thesis project has examined the moisture dependency of shear strength in the loess soils of Banks Peninsula. These dominant silt materials are generally regarded as having an angle of internal friction between 25 and 30°, and cohesion of zero, when the soil is saturated. However, soil behaviour in terms of slope stability would appear to support a cohesion value higher than zero as vertical cliffs of loess can be seen to stand indefinitely. It is agreed that loess soils upon saturation do show very low shear strengths, but these soils rarely become saturated due to their low permeability (k<10⁻⁶). To address the quantity of water content dependency of shear strength, five field sites have been sampled for unconsolidated undrained triaxial shear strength to determine c and ø at varying water contents in the total stress state, which most closely simulates observed behaviour. The field sites were: 1) Moncks Spur primary airfall in situ loess; 2) Stonehaven Subdivision loess-colluvium; 3) Worsleys Spur primary airfall in situ loess; 4) Duvauchelle primary airfall in situ loess; 5) Whaka Terrace uncompacted loess fill. Nominated water contents for the shear testing program were 6%, 10%, 14% and "as wet as possible". Samples were prepared in the laboratory by immersing the stainless steel sampling tube containing the soil sample in water for up to 2 weeks to a water content maximum, and then drying them back to the nominated water content. Analysis of results of all five field sites tested at the four nominated water contents showed a new cohesion trend, which has not previously been reported in Banks Peninsula Loess. As water contents increase from 6% cohesion increases to a maximum value and then decreases, whilst for angle of internal friction there is a linear decrease over the entire range of water contents, for example 52° at 6% to 13° at 23% for Stonehaven Subdivision loess colluvium. Maximum values for primary airfall (in situ) Port Hills loess fill and colluvium the cohesion maximum was approximately 210 kPa at 10% water content. Friction angle trends were quite similar for all sites. A secondary aim of this thesis was to examine lime stabilising effects on compacted loess fill. Trials were carried out at the Whaka Terrace field site where excavated loess fill from a test pit was mixed with hydrated lime at 2% by weight of the total soil mass, and then compacted back into the same test pit so that the treated soil could be cured under field conditions. Untreated samples were taken from the base of the test pit and treated soils were extracted from the treated compacted layers at intervals of 1 week, 1 month and 2 months after compaction. Samples were prepared at two different water contents, 15% and as "as wet as possible", so that a shear strength dependence on water could also be established. Results suggest that 15% water content treated samples had 30-40 kPa more cohesion and 5° more angle of internal friction than the "as wet as possible" treated samples. For example after 7 days of field curing cohesion was recorded at 30.7 kPa and 4 kPa for water contents of 16.9% and 19.1% respectively, and angle of internal frictions were 30° and 23.4° for the same respective water contents. Shear strength values increased over time with a rapid rate of increase after the first week of curing, and then a slowing down thereafter. A maximum cohesion of 25 kPa and angle of internal friction was recorded for samples cured in the field for 68 days as compared to untreated loess, which had cohesion of 0 kPa and 11.5° for the angle of internal friction. Both were tested at "as wet as possible" water contents. Future work should entail the determination of effective stress parameters c and ø’ by determining matric suctions (negative pore pressures) to determine if the trend seen in this project is something new or an artefact of the analysis used, and more study centred on loess from the Akaroa Harbour region. In conclusion it has been demonstrated in this thesis that Banks Peninsula Loess shear strength has a dependency on water content in terms of total stress parameters c and by way of using the triaxial test apparatus in the unconsolidated undrained condition.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Smith, Susan Leslie. "Distribution, movements and abundance of Hector's dolphin around Banks Peninsula". Thesis, University of Canterbury. Department of Zoology, 1992. http://hdl.handle.net/10092/2801.

Testo completo

Abstract (sommario):

New Zealand's first Marine Mammal Sanctuary was established around Banks Peninsula in 1988, to protect Hector's dolphins from entanglement in gillnets. Understanding distribution and movements of Hector's dolphins inhabiting Banks Peninsula has important implications for their effective management. The need to assess the effectiveness of restricting gillnetting also underscores the need for ongoing estimates of the size of the Banks Peninsula Hector's dolphin population. I analysed spatial and temporal movements of distinctive Hector's dolphins identified around Banks Peninsula. A substantial number of dolphins I identified in the northern portion of Banks Peninsula have been sighted in the southern portion of Banks Peninsula but none of the individuals I identified have been sighted north or south of the peninsula (Slooten, Dawson, Stone and Yoshinaga, unpub. data). These results suggest that Hector's dolphins resident around Banks Peninsula, are a single interacting population. I assessed the applicability of mark-recapture methods using photo-identification of distinctive individuals to estimate the size of the Banks Peninsula population of Hector's dolphins. The maximum average capture probability for Hector's dolphins around Banks Peninsula during my study was in the range of "poor" data. During my study, small sample size and low recapture rates of identified dolphins was generally the case. These results indicated that numbers of Hector's dolphins around Banks Peninsula cannot be estimated reliably from mark-recapture methods with the data which is currently available. I conducted surveys to estimate the abundance of Hector's dolphins in the northern portion of Banks Peninsula. I also used survey data to examine the temporal and spatial distribution of dolphins in the study area. No more than 123 dolphins were counted on a survey and on approximately 70% of surveys, fewer than 41 were counted. I found no significant difference in number of dolphins counted during November to March, suggesting that conducting surveys during this period is an appropriate sampling strategy for estimating abundance. There was a highly significant association between abundance and location, indicating it is inappropriate to extrapolate abundance estimates from one area to another based on a simple density 1 area relationship. Estimates of abundance for Hector's dolphins in the northern portion of Banks Peninsula for 1990/91 and 1991/92 were in the range of previously reported estimates for Banks Peninsula.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Nikoloff, Megan Helena. "Seed and microsite limitation in Clematis vitalba on Banks Peninsula". Thesis, University of Canterbury. Biological Sciences, 2011. http://hdl.handle.net/10092/6730.

Testo completo

Abstract (sommario):

Clematis vitalba, introduced to New Zealand from Europe in the early 1900s, is an invasive weed which poses a high risk to native forest remnants, particularly in the central North Island and upper and central South Island. Its dispersal techniques and rate of spread make it a particular challenge for managers attempting to control its range expansion. Is the population abundance and distribution of C. vitalba on Banks Peninsula seed or microsite limited? I tested the presence of seed limitation in three populations of C. vitalba at two sites by measuring seed dispersal and checking for the presence of a soil seed bank. At a location where C. vitalba is absent due to control efforts, I investigated the presence of a long-term seed bank and long-distance dispersal. I also tested the degree of microsite limitation in C. vitalba at the two sites by surveying the natural distribution of seedlings, monitoring seedling emergence after seed addition and measuring the survival and growth of planted seedlings. Soil samples taken from the Port Hills and Akaroa sites contained low amounts of previous-season C. vitalba seed (an average of 0.0125 seeds per m² in the forest and 0.0025 per m² in the open) and cofirmed the presence of a small short-term soil seed bank. Seed rain was greater at Akaroa (3912 seeds caught) than on the Port Hills (1507 seeds caught), which is also reflected in a larger seed bank at Akaroa. The distribution of natural seedlings and growth of planted seedlings suggests that the optimum habitat for this species varies among different life stages. At the site cleared of C. vitalba more than eight years ago, there were no seeds in the seed bank but new seeds arrived by long-distance dispersal. Overall, these results suggest that microsite limitation has a greater role near the parent plant and seed limitation becomes more pronounced at increasing distance from the seed source. Clematis vitalba populations continue to spread from ongoing long-distance dispersal and short-distance dispersal with lateral expansion of established populations; established populations are more likely to be limited by the availability of microsites while expanding populations will be seed limited at the edge of the population where plant density is low.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Livermore, Andrew B. "Cinder cones of the Lyttelton Volcano, Banks Peninsula, New Zealand". Thesis, University of Canterbury. Geology, 1999. http://hdl.handle.net/10092/6858.

Testo completo

Abstract (sommario):

Cinder cones are common on Banks Peninsula and this study concentrates on eleven sites situated on the Lyttelton Volcano. The study focuses on the structure, petrology and geochemistry of cinder cones and discusses their eruptive history. Lyttelton volcanism began in the Miocene (10.8 Ma) with early (L1) activity centred near "Head of the Bay". Constant replenishment of the main chamber caused L1 lavas to be dominantly basaltic with limited differentiation. The development of a large cone resulted in distension which caused the development of horizontally fed radial dikes. Initial dike activity was low and lavas were dominantly fed from the central conduit with little flank activity. As L1 grew though, dikes became more common and so did cinder cone activity on the flanks. Cinder cones would have been fed by volatile rich magmas quickly reaching the surface via dikes and hence erupting explosively. The increase in dikes during L1 also caused the increasing development of more evolved magmas that fed lavas. Then during a quiescent period there was large-scale collapse of the eastern flank, followed by erosion and weathering of the L1 volcanic edifice during which activity shifted north-east to "Charteris Bay". Renewed (L2) activity after the quiescent period gave rise to more evolved lavas due to the large increase in dike activity, caused by the large amounts of stress acting on the edifice. Hence cinder cone activity on the flanks was also very common. Cinder cone samples are dominated by phenocrysts of plagioclase, clinopyroxene, olivine and Ti-magnetite and show a wide range of mineral textures. This suggests that crystals have grown under a variety of temperatures and pressures and/or been derived from magmas of different compositions. Geochemically the cones are part of an alkaline basalt-hawaiite-mugearite- benmoreite-trachyte association. The deposits in this study are all inferred to have formed by Strombolian and Hawaiian type eruptions due to their small dispersal areas. These eruptions formed cinder cones whose morphology depended on numerous factors, all of which contributed to their overall development: In this study the deposits have been classified into four facies based on welding, dip direction, block and bomb size, colour and the presence or absence of some clasts. The Vent Facies consists of densely welded grey/black fused spatter and represents vent and early formed products. Vesicularity is <20% with outcrops resembling massive lava; occasionally, however, dips towards the vent region can be found, establishing an origin within the vent The Proximal Facies consists of >80% flattened clasts with deposits inferred to be welded due to their flattened nature. Spatter flows are common in the facies due to the rapid accumulation of spatter and its flowage. The Medial Facies consist of crudely bedded bomb, block and lapilli beds. Clasts are undeformed and non-welded. The Distal Facies consist of lapilli, ash, and crystals. Rare bombs occasionally occur and the deposits are generally well sorted and bedded. Overall, throughout each of the facies, clast size and welding decreases with increasing distance from the vent area.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Goldwater, Stefan. "Slope Failure in Loess. A detailed investigation Allandale, Banks Peninsula". Thesis, University of Canterbury. Geology, 1990. http://hdl.handle.net/10092/9378.

Testo completo

Abstract (sommario):

This study investigates a slope failure complex in loess at Allandale, Lyttelton Harbour. Literature relevant to the slope stability and strength of Banks Peninsula loessial soils is reviewed. Laboratory and in situ strength testing shows that both C and P layer loess in a partially saturated state displays a significant reduction in undrained shear strength with increasing degree of saturation. Strength reduction can be attributed to reduced pore water tension due to capillary suction which results from an increased degree of saturation. The moisture controlled strength component in partially saturated loess can be defined by any two of dry density, moisture content and degree of saturation. When comparing loess C and P layer remoulded strengths with peak strengths, the P layer is significantly more sensitive to remoulding than C layer. Drained direct shear testing of C layer loess produces remoulded and peak strength parameters of c'=O, Ø'=28.4° and c'=6kPa, Ø '=28.4° respectively. Drained direct shear testing of P layer loess produced remoulded and peak shear strength parameters of c'=O, Ø '=28.4° and c'=20kPa, Ø '=28.4° respectively. The slope failure complex investigated has been formed by an earthflow initiated by a tension crack in C layer loess (which acts as an unconfined leaky aquifer). Subsequent retrogressive upslope and lateral migration of the slope failure complex involves "turfmat slides" in S layer loess which also acts as an unconfined leaky aquifer, and more tension crack initiated earth flows in C layer loess. Back analysis suggests both forms of slope movement may have failed by translational sliding at the base of their respective loess layer, with a piezometric level coincident with the ground surface. Mobilisation of the "turfmat slide", requires drained remoulded shear strengths, whereas mobilisation of the earth flow is more likely to involve drained peak shear strengths.

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Hay, Robert Bruce. "Sense of place: Cross-cultural perspectives from Banks Peninsula, New Zealand". Thesis, University of Canterbury. Geography, 1990. http://hdl.handle.net/10092/4704.

Testo completo

Abstract (sommario):

Sense of place is an important dimension in many people's lives. Through long residence in a region a person tends to become attached to that place, expressing both territoriality and affection for it. Bonding to a place is largely subconscious, however. If a person gains perspective by being distant from his or her place, a greater awareness of place bonds can build upon his or her sense of place, making it even stronger. Cultural influences can also build a sense of place, especially among indigenous people. Previous sense of place research has seldom been empirically based, and has tended to focus upon modern peoples, yet researchers make generalizations as if their research applies to all humanity. Cross-cultural research, founded in fieldwork, can both confirm and extend theory on sense of place. My research project has examined an indigenous people's sense of place, and contrasted it with that of a modern people. Banks Peninsula, New Zealand, has been my study area, where a large number of Maori (indigenous) and pakeha (modern, and of European descent) peoples were interviewed in depth to determine the character of their respective senses of place. My field research objectives were to learn about an indigenous people's sense of place, at the level of cosmology; to investigate how sense of place varies among people; to see how sense of place develops; and to uncover the essence of sense of place itself. Interviews formed the bulk of the data, with 270 Peninsula respondents interviewed at length in their homes, and another 80 Peninsula out-migrants interviewed elsewhere in New Zealand. Group interviews supplemented the Peninsula data base, as did less detailed talks with holiday home owners, long-term campers, tourists and school children. Community events, both Maori and pakeha, were attended throughout the fieldwork period, which extended from November, 1987, through to February, 1989. Results were analyzed primarily through qualitative means, as an ethnographic and phenomenological methodology directed my research. However, as a social survey was also conducted, quantitative analyses were done to ascertain the extent of trends among responses from interviews, as well as to find inter-relationships in those trends. Themes and insights became apparent in the qualitative analyses; respondents' insights are shown in the dissertation through excerpts from interviews. Theory was developed both during and after fieldwork, with self-reflection and comparison with previous research instrumental in that development. Major differences were identified between indigenous and modern peoples in the way in which each develops their sense of place. Maori are linked to the earth through cosmology, with creation myths centering them within the cosmos in one particular place. The tribal land upon which Maori dwell is both respected and loved; Maori belong to the earth, especially around their marae (meeting house and grounds), referring to that location as papa kainga (home ground) and their

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Dorsey, C. J. "The geology and geochemistry of Akaroa volcano, Banks Peninsula, New Zealand". Thesis, University of Canterbury. Geological Sciences, 1988. http://hdl.handle.net/10092/7524.

Testo completo

Abstract (sommario):

This thesis presents a detailed geological, petrological and geochemical study of Akaroa Volcano, Banks Peninsula, New Zealand. The Akaroa Volcanic Group is defined as comprising all the volcanic products of central, flank and parasitic vent eruptions in the south-eastern two-thirds of Banks Peninsula, which collectively form Akaroa Volcano. Field mapping has shown that the lavas and pyroclastics of which Akaroa Volcano is constructed can be grouped into an Early Phase and a Main Phase. Early Phase rocks (?11-9 Ma) are restricted in outcrop to the inner shoreline of Akaroa Harbour. The oldest exposed basaltic lava flows of Akaroa Volcano are assigned to Early Phase I. Early Phase II comprises extensive trachyte tuffs, breccias, agglomerates, flows, sills, and a large dome, with minor basaltic tuffs, and appears to represent a major episode of eruption of trachytic lava marking the end of the construction of a proto-Akaroa Volcano. Weathered basaltic flows, tuffs, lahars, scoria cones and pyroclastic breccia of Early Phase III unconformably overlie rocks of Early Phase II. The contact between Early Phases II and III shows considerable relief indicating a period of erosion prior to eruption of Early Phase III flows and pyroclastics. A diverse stratigraphy and a significant portion of the early history of Akaroa Volcano remains buried beneath sea level. A period of prolonged weathering and erosion occurred prior to the eruption of Main Phase lava flows and pyroclastics. The main cone of Akaroa Volcano is constructed predominantly of hawaiite lava flows and pyroclastics and rare mugearite, benmoreite and trachyte lava flows of the Main Phase, erupted 9-8 Ma. Activity was hawaiian to mildly strombolian in character. Throughout its eruptive history, Akaroa Volcano was intruded by predominantly trachytic dikes of the Akaroa radial dike swarm, and five large trachyte domes. Dikes radiate from a broadly defined central zone south to south-east of Onawe Peninsula which coincides with the inferred location of the main conduit, and with the maxima of local bouguer and isostatic gravity anomalies. Analysis of the gravity anomaly surfaces indicates a substantial sub-surface intrusive complex containing> 615 km³ of intrusive material. Panama Rock trachyte dome can be seen to have been fed by a large dike of the radial dike swarm and a similar origin is inferred for the other intrusive trachyte domes. Akaroa Volcanic Group lavas have a mineralogy typical of alkaline volcanic associations, dominated by olivine, Ti-rich calcic clinopyroxene, titanomagnetite, plagioclase and apatite. Rare kaersutite megacrysts occur in evolved lavas, and per alkaline differentiates contain arfvedsonite and aenigmatite. Minor biotite and amphibole occur in coarse-grain basic lavas. Akaroa Volcanic Group lavas comprise a mildly to moderately (sodic) alkaline association, with a trend of moderate iron enrichment. Two end-member lineages are recognised: a dominant basalt-hawaiite-mugearite-benmoreite-trachyte lineage with ne-, hy- and qz-normative variants, and a basanite-nepheline hawaiitenepheline mugearite-nepheline benmoreite-phonolite lineage. Peralkaline differentiates are also recognised. The dominant lava type is hawaiite, rather than basalt, and most lavas have Mg numbers (100 X Mg²⁺ /Mg²⁺ +Fe²⁺) in the range 35-48, indicating that Akaroa Volcanic Group lavas do not represent primary magmas but have undergone significant high pressure fractionation. Geochemically, Akaroa Volcanic Group lavas form a comagmatic suite characterised by (i) A logarithmic decrease in MgO, TiO₂, Cr, Ni and V; (ii) A linear decrease in CaO and FeO; (iii) A linear increase in Na₂O, K₂O, Y, Nb, Rb, La, Ce, Nd, Ga, Pb, Th, and Ba; (iv) A complex variation in Al₂O₃; (v) A rapid increase in P₂O₅ and Sr followed by a rapid decrease; and (vi) An increase in REE abundances with increasing differentiation. These variations are consistent with evolution by fractional crystallization of olivine, clinopyroxene, titanomagnetite, plagioclase, apatite and possibly kaersutite. Lavas have linear, parallel, LREE-enriched REE patterns (CeN/YbN ≈ 7-9.5) indicative of magma generation by small degrees of partial melting of a garnet peridotite mantle source. Covariance of ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd isotope ratios is consistent with derivation of Akaroa Volcanic Group magmas from a time-integrated, LREE-depleted mantle source, whereas Sm/Nd and Rb/Sr trace element ratios indicate a LREE-enriched source. Mantle enrichment processes prior to, or associated with, the melting event and/or very small degrees of partial melting (< 1%) are postulated to account for this dichotomy. Qz-normative felsic lavas have high ⁸⁷Sr /⁸⁶Sr isotope ratios, and high-level crustal contamination appears to be an important process in the evolution of these lavas.

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Fraser, Iain. "The effects of forest fragmentation on stream invertebrate communities on Banks Peninsula". Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1353.

Testo completo

Abstract (sommario):

The removal of indigenous forest and associated fragmentation of habitats has probably had significant impacts on the diversity of stream communities in New Zealand. In this study I investigated the effects of forest fragmentation on stream invertebrate communities on Banks Peninsula. Six catchments were investigated, three with continuous indigenous forest in the riparian zone and three with fragmented indigenous riparian forest. An extensive benthic survey was conducted at three sites in each river catchment, one downstream on the mainstem of the river and two sites in different headwater tributaries. Adult sampling, consisting of malaise and sticky trapping, was also conducted at a sub-set of sites. Taxonomic richness of both the benthic and adult communities was significantly higher in continuous forest than in fragmented forest, and the composition of benthic communities also differed between continuous and forest fragments. Furthermore, benthic invertebrate densities were higher in fragments than continuous forest sites. The fragments in the headwaters were more likely to support forest specialist taxa (e.g. the stonefly Zelandobius wardi, and the caddisfly Costachorema peninsulae), than the downstream fragments. My results indicate that forest fragmentation has resulted in marked changes in benthic communities on Banks Peninsula, and that location of the fragment within the catchment also is important in influencing the diversity and composition of benthic communities. The maintenance of indigenous forest in the headwaters of streams may be essential for the persistence of endemic and forest specialist taxa on Banks Peninsula.

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Hampton, Samuel Job. "Growth, Structure and Evolution the Lyttelton Volcanic Complex, Banks Peninsula, New Zealand". Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/4117.

Testo completo

Abstract (sommario):

The Lyttelton Volcanic Complex, north-western Banks Peninsula, New Zealand, is comprised of five overlapping volcanic cones. Two magma systems are postulated to have fed Banks Peninsula’s basaltic intraplate volcanism, with simultaneous volcanism occurring in both the north-western and south-eastern regions of Banks Peninsula, to form Lyttelton and Akaroa Volcanic Complexes respectively. The elongate form of Banks Peninsula is postulated to relate to the upward constraining of magmatism in a north-west / south-east fault bounded zone. The Lyttelton Volcanic Complex resulted from the development of a pull-apart basin, with a number of releasing bend faults, controlling the location of eruptive sites. Cone structure further influenced the pathway magma propagated, with new eruptive sites developing on the un-buttressed flanks, resulting in the eruption and formation of a new cone, or as further cone growth recorded as an eruptive package. Each cone formed through constructional or eruptive phases, termed an eruptive package. Eruptive packages commonly terminate with a rubbly a’a to blocky lava flow, identified through stratigraphic relationships, lava flow trends and flow types, a related dyking regime, and radial erosional features (i.e. ridges and valleys). Within the overall evolving geochemical trend of the Lyttelton Volcanic Complex, are cyclic eruptive phases, intrinsically linked to eruptive packages. Within an eruptive package, crystal content fluctuates, but there is a common trend of increasing feldspar content, with peak levels corresponding to a blocky lava flow horizon, indicating the role of increased crystalinity and lava flow rheology. Cyclic eruptive phases relate to discreet magma batches within the higher levels of the edifice, with crystal content increasing as each magma batch evolves, limiting the ability of the volcanic system, over time, to erupt. Evolving magmas resulted in explosive eruptions following effusive eruptives, and / or result in the intrusion of hypabyssal features such as dykes and domes, of more evolved compositions (i.e. trachyte). Each eruptive package hosts a radial dyke swarm, reflecting the stress state of a shallow level magma chamber or a newly developed stress field due to gravitational relaxation in the newly constructed edifice, at the time of emplacement. Two distinct erosional structures are modelled; radial valleys and cone-controlled valleys. Radial valleys reflect radial erosion about a cone’s summit, while cone-controlled valleys are regions where eruptive packages and cones from different centres meet, allowing stream development. Interbedded epiclastic deposits within the Lyttelton lava flow sequences indicate volcanic degradation during volcanic activity. As degradation of the volcanic complex progressed, summit regions coalesced, later becoming unidirectional breached, increasing the area of the drainage basin and thus the potential to erode and transport extensive amounts of material away, ultimately forming Lyttelton Harbour, Gebbies Pass, and the infilled Mt Herbert region. Epiclastic deposits on the south-eastern side of Lyttelton Harbour indicate a paleo-valley system (paleo-Lyttelton Harbour) existed prior to 8.1 Ma, while the morphology of the Lyttelton Volcanic Complex directed the eruptive sites, style and resultant morphology of the proceeding volcanic groups.

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Willems, Nancy. "Forest structure and regeneration dynamics of podocarp/hardwood forest fragments, Banks Peninsula, New Zealand". Lincoln University, 1999. http://hdl.handle.net/10182/1301.

Testo completo

Abstract (sommario):

Although species maintenance in small forest fragments relies on successful regeneration and recruitment, few studies have examined the effects of fragmentation on regeneration processes. New Zealand's podocarp species rely on large disturbance openings operating across a vegetated landscape to stimulate regeneration. Clearance of vegetation that results in small fragments of forest removes regeneration opportunities for podocarps by destroying the intact vegetation mosaic, and as a result may exclude disturbances of the scale necessary for podocarp regeneration. Fragmentation alters the disturbance regime of the landscape, with important implications for the regeneration of podocarps on Banks Peninsula. The four remaining lowland podocarp-hardwood fragments on Banks Peninsula were sampled to determine the structure and regeneration patterns of podocarps and to assess their long term viability. Density, basal area, and size and age class distributions were used to examine current composition, and in conjunction with spatial analysis, to identify past regeneration patterns and infer likely future changes in composition and population structure. Podocarp size and age class structures for three of the four fragments were characteristically even-sized and relatively even-aged (eg; Prumnopitys taxifolia c. 350 to 600 years), with little or no regeneration for approximately the last 200 years (old-growth fragments). Regeneration of the current podocarp canopy in the old-growth fragments may have been stimulated by flooding. The fourth younger fragment showed much more recent regeneration with Prumnopitys taxifolia, Podocarpus totara and Dacrycarpus dacrydioides mostly 80-160 years old, and substantial populations of seedlings and saplings, probably as a result of anthropogenic fire. In the absence of major disturbance the podocarp component in forest fragments on Banks Peninsula is likely to decline with composition shifting towards dominance by hardwood species. There is some evidence to suggest that canopy collapse will stimulate some podocarp regeneration within the fragments, however it appears to be unlikely that podocarps will persist on Banks Peninsula indefinitely within the fragments studied. There is an urgent need for more quantitative research in New Zealand fragmentation literature, and a need for more emphasis on processes. Banks Peninsula offers potential for a more landscape scale approach in forest management, and the maintenance of regenerating scrub in pockets about the Peninsula may offer the regeneration opportunities for podocarps that are lacking within protected fragments. My study took a quantitative approach in examining the effects of forest fragmentation on the demographics of podocarps and compositional change in forest fragments on Banks Peninsula.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Namjou, Parviz. "Hydrogeological and geophysical investigation of the groundwater system in the Kaituna Valley, Banks Peninsula". Thesis, University of Canterbury. Geology, 1988. http://hdl.handle.net/10092/5554.

Testo completo

Abstract (sommario):

In the Kaituna Vally an intensive change in land use has produced an increased demand for water, particularly groundwater. The present study was undertaken in order to provide an adequate data base to develop appropriate water management strategies for the Kaituna Valley and other similar catchments in the area. Shrinkage fractures within lava flows control the vertical movement of water whilst horizontal water flow occurs mainly within brecciated lava. Chemical and environmental water analysis indicate that local precipitation through volcanic fractures is the main mechanism for groundwater recharge in the area. The impermeable layers (tuff and ash) between lava flows and subvertical dikes divide the subsurface volcanic rocks into a number of groundwater compartments each with its own water level and outlets. Outlets will be into adjacent to the valley floor sediments. The outlet through the gravelly layer in this zone is the main mechanism of groundwater replenishment within the valley floor deposits. Geophysical investigations have identified two aquifers below the valley floor. The lower aquifer with an average transmissivity value of 4.45 x 10-3 m2/s has a variable thickness ranging between 2 m to 60 m. the average transmissivity for the upper aquifer is 14.5 x 10-3 m2/s with an average thickness of 24m. Using the hydrological water Balance for the monitored water year (June 1986 – may 1987), the total rate of recharge to the groundwater system was 86 mm out of 1900 mm total rainfall. If groundwater is to be used for drinking, it must be treated for excessive iron content in well M36/1344 bot.. of which draw from the lower aquifer.

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Trent, Aleysha Jennie. "Shifting eruption styles during the emergence of Akaroa strato-shield volcano, Banks Peninsula, New Zealand". Thesis, University of Canterbury. Geological Sciences, 2012. http://hdl.handle.net/10092/7773.

Testo completo

Abstract (sommario):

The uniquely eroded harbour of Akaroa volcano provides a rare opportunity to study the dissected core of the basaltic to trachytic strato-shield volcano. With key exposures of both the early phase trachytic to basaltic eruptive deposits and the later phase voluminous basaltic deposits (9.6 – 8.6 Ma) that make up the majority of the emergent volcanic flank. This thesis aims to illustrate the volcanic processes that dominate the diverse early stages of emergent volcanism. We have built on previous research to produce detailed maps and stratigraphic logs of key extrusive and intrusive sequences. We further identify eruptive packages and their facies to identify eruptive centres, and correlate early stratigraphy. This study reveals the emergence of local volcanic centres with differing eruptive styles, chemistry and volumes. An explosive phreatomagmatic trachyte tuff ring and dome/flow complex dominated early eruptions. This extensive trachytic centre had multiple phases of activity, displaying both temporal and spatial transitions in style. Temporal facies transitions consisted of changes from a subaqueous to emergent hyaloclastite dome, to an explosive phreatomagmatic trachyte tuff ring to an effusive trachytic dome (Fig 7.1 – Fig 7.7). Whereas spacial transitions consisted of lateral facies variations within the pyroclastic surge and air fall deposits of the tuff ring reflecting 'en route' changes in deposition. Smaller volcanic centres migrated around the margins of this larger trachytic centre (Fig 7.1 – Fig 7.7). These eruptions variously interacted with seawater forming small tuff and scoria cones. Generally, these smaller eruptions show a progression from low angle phreatomagmatic palagonite rich lapilli tuffs to steeper bedded spatter and bomb dominated deposits. This transition in facies likely represents the emergence of individual volcanoes with later deposits showing less evidence for interaction with seawater. These discrete centres later coalesced through deposition of the more extensive lava flows forming the early volcanic complex of Akaroa Volcano. Erosional processes dramatically reshaped the volcanic complex. Bays of the present day harbour represent eroded basaltic explosive centres, as pyroclastic units are preferentially eroded by the sea. Whereas more coherent lavas tend to form headlands within the harbour. In summary, the findings of this research have refined maps, stratigraphy, lithologic descriptions and facies interpretations of Akaroa volcanoes emergent deposits. Thus enabling the development of a geological formation model for the early to emergent stages of Akaroa Volcano. Furthering the understanding of early to emergent, shallow magmatic, volcanologic processes, associated with alkali basaltic and trachytic eruptions at Akaroa Volcano.

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Jasson, René. "Management of Acacia species seed banks in the Table Mountain National Park, Cape Peninsula, South Africa /". Link to the online version, 2005. http://hdl.handle.net/10019/1059.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Altaye, Elias. "The geology and geochemistry of the north-eastern sector of Lyttelton volcano, Banks Peninsula, New Zealand". Thesis, University of Canterbury. Department of Geology, 1989. http://hdl.handle.net/10092/3865.

Testo completo

Abstract (sommario):

Miocene volcanic activity constructed the Lyttelton composite cone 11 -10 Ma ago. The Lyttelton volcano which forms the north western half of Banks Peninsula represents a significant volume of mafic volcanic rocks together with some of felsic and minor intermediate composition. In addition to these, the volcano is characterized by pyroclastic deposits (lahars and lithic-crystal tuffs). Lyttelton lavas are intruded by numerous radial dikes and also by a variety of lava domes, sills and plugs. The volcanism was mainly Hawaiian in style, with some Vulcanian and occasional Strombolian styles of activity. Within this composite volcano, two major phase of volcanic activity are recognized. These are the main phase (the older) and late phase (younger) Lyttelton volcanics defined on the basis of field relationships, petrography and geochemistry. The late phase volcanics are designated formally as the Mt Pleasant Formation. The main and late phase Lyttelton volcanics range from mafic to felsic rocks compositions. The dikes range from basalt to trachyte and intruded the volcano during the main and late phase of volcanic activity. Sills and intrusions have felsic compositions. The major valleys and the lahar deposits represent periods of degradation of the active cone. Both the main and late phase (Mt Pleasant Formation) Lyttelton volcanics are alkaline tending transitional in geochemical affinity. The alkaline, sodic series Lyttelton rocks are members of the alkali olivine basalt association and this designation is consistent with mineralogy. Some intermediate and felsic Lyttelton rocks are subalkaline and potassic in composition, but they are classified as alkaline olivine basalt associations on the basis of their mineralogy. There are geochemical distinctions in major oxides, trace -elements and normative mineralogy between the main and late (Mt Pleasant Formation) Lyttelton rocks. The petrogenesis of the main and late Lyttelton volcanics mafic lavas is best explained by low pressure crystal fractionation of the observed phenocryst phases. The intermediate and felsic rocks are derived by similar processes with minor crustal contamination. Tectonically, Lyttelton volcanics represent “within plate” alkaline mafic volcanism.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Sewell, R. J. "The volcanic geology and geochemistry of central Banks Peninsula and relationships to Lyttelton and Akaroa volcanoes". Thesis, University of Canterbury. Geology, 1985. http://hdl.handle.net/10092/7227.

Testo completo

Abstract (sommario):

Based on field-mapping and geochemistry of lavas outcropping between the two stratovolcanic centres of Lyttelton and Akaroa, a new Miocene volcanic stratigraphy for central Banks Peninsula has been established. Five lithologically and geochemically distinct phases of volcanism are recognised. These are the Lyttelton Volcanics (11 – 10 Ma), Mt Herbert Volcanics (9. 7 - 8.0 Ma), Akaroa Volcanic s (9.0 - 8.0 Ma). Church Volcanics (8.1 - 7.3 Ma) and Stoddart Volcanics (7.0 - 5.8 Ma). A model is proposed to account for the volcanic evolution of Banks Peninsula. The Lyttelton Volcanics range in composition from hawaiite to trachyte and consist of a mildly alkaline to transitional association of lava flows, pyroclastic deposits and high level intrusive rocks. Eruption style was dominantly of the mild Strombolean to Hawaiian-type and during the later stages of volcanic activity, a large breach formed in the south-east sector of the Lyttelton crater wall. The Mt Herbert Volcanics comprise a volcanic complex of mildly alkaline basalt plugs and lava flows, epiclastic and pyroclastic rocks that record the migration of volcanic activity from the Lyttelton centre to that of Akaroa. Field and geochemical relationships together with new K-Ar data, show that the Mt Herbert Volcanics can be divided into five formations. In order of eruption these are: - 1/ Kaituna Olivine-Hawaiites; 2/ Orton-Bradley Volcanic Suite; 3/ Port Levy Volcanic Suite: 4/ Castle Rock Hawaiites; 5/ Mt Herbert Hawaiites. Volcanic products associated with the Orton-Bradley Volcanic Suite infill the breach in the south-east crater wall of Lyttelton Volcano. There is evidence that a crater lake occupied the floor of Lyttelton Volcano during this infilling. Concomitant lacustrine deposition and Surtseyan volcanic activity is recorded by sub-aqueous pyroclastic deposits. Lavas of the Mt Herbert Volcanics were erupted from two main centres located respectively beneath the present position of Mt Herbert and in the vicinity of Port Levy. Eruption of lavas from the main vents was accompanied by the building of local Surtseyan and Strombolean tuff cones. These are recorded by base-surge and airfall deposits. The mineralogy and geochemistry of the Mt Herbert Volcanics indicate that magmas evolved in reservoirs near the base of the crust. Magmas of the Kaituna Olivine-Hawaiites have undergone selective crustal contamination. The Akaroa Volcanics in central Banks Peninsula comprise a mildly alkaline association of basalt to mugearite lava flows and high-level basaltic to trachytic intrusive rocks. Lavas reached the central area of Banks Peninsula during the final stages of Mt Herbert Volcanism. Geochemical data indicate that Akaroa magmas evolved mostly in reservoirs near the base of the crust. The Church Volcanics represent the most geochemically primitive rocks in central Banks Peninsula. A newly defined formation of basanitoid lava flows, dikes and plugs (Darra Basanitoids) is shown to be chemically related to alkali-basalt lava flows defined as the Church Bay Olivine-Basalts. The mineralogy and geochemistry of the Church Volcanics indicate that magmas were derived from different degrees of partial melting from a common mantle source. Magmas ascended directly through the crust without significant interruption. The Stoddart Volcanics comprise a volcanic group dominated by olivine-basalt to olivine-hawaiite lava flows and plugs, minor basanite and conglomerate units and rare olivine-hawaiite dikes. The Stoddart Volcanics are divided into two formations:- the Stoddart Point Olivine-Basalts and the Kaioruru Olivine-Hawaiites. Mineralogical and geochemical data indicate that Stoddart Volcanics were derived from different degrees of partial melting from a common mantle source. Some of these lavas underwent selective crustal contamination during ascent to the surface. Geochemical and isotopic characteristics of lavas from central Banks Peninsula indicate that magmas were derived from a common, light Rare-Earth-Element enriched mantle source. Tectonically, all the lavas of central Banks Peninsula are within-plate basalts and show no affinity with subduction-related volcanism. A within-plate stress field corresponding to the intersection of E - W trending faults of the Chatham Rise and NE - SW trending faults of the transform plate boundary through the South Island is considered to have triggered the Miocene volcanism recorded on Banks Peninsula. A model is proposed to account for the petrogenetic evolution of Banks Peninsula magmas during the Miocene.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Jasson, Rene. "Management of Acacia species seed banks in the Table Mountain National Park, Cape Peninsula, South Africa". Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1655.

Testo completo

Abstract (sommario):

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2005.
Within the Table Mountain National Park (TMNP), Western Cape, South Africa, various management practices have been undertaken in the removal of alien vegetation. While considerable success in the control of alien plants is evident from the removal of standing plants, it is not known if this effort has actually made any long-term difference in the effort to eliminate alien vegetation from the TMNP. This is because no coordinated effort has been made to assess the extent of the alien seed bank, nor the effect that clearing (including the use of fire) has on this seed store. This study investigates the extent of pre- and post-fire Acacia saligna seed banks under differing stand ages, differing clearing techniques and different habitats in the Cape Peninsula National Park. Firstly, the focus is on two alien plant management techniques: The first technique involves clearing and stacking of biomass for burning during winter (stack burn technique), the second technique involves burning of standing alien plants (standing/block burn technique) to decrease heat release at the surface. Secondly, the extent of Acacia species seed banks along the Silvermine River is also investigated with the aim of determining the extent of alien seed stores in this habitat and therefore the long-term restoration potential of the riparian corridor. The primary question addressed in the first study is: “Under what clearing technique will most of the alien seed bank be reduced?” The secondary question reads: “Is seed bank density and distribution directly related to age of dense infestation of the alien vegetation stand and habitat?” The primary question addressed in the second study is: “What is the vertical, lateral and longitudinal distribution and density of Acacia species seed banks along the Silvermine River?” The secondary question reads: “Is seed density and distribution influenced by above ground density of alien vegetation?” In both riparian and terrestrial systems, alien soil seed banks accumulate in high densities where aboveground alien Acacia vegetation is dense. Most of the seed occurs in the upper soil layer, but seed density decreases with depth with an exception of a high seed density at a low depth in one of the samples in the riparian system. Intense fires are most effective in reducing seed stores and removing aboveground alien vegetation in both riparian and terrestrial fynbos systems. After burns, both stack and stand burns have shown a significant decrease in seed density especially in the upper layers but there is still much seed that remained in the matrix area between stacks. The cooler winter burns resulted in less destructive, lower temperatures that aided higher seedling recruitment. Mature stands of Acacia saligna tend to have greater seed stores than immature stands and habitats with deep colluvial soils have a greater density and also greater vertical distribution of seeds. The vertical distribution of the riparian system differed from the fynbos terrestrial system in that seeds were found down to lower depths. Along the river, seed density also increased laterally with more seeds occurring in the terrrestrial sections than in the channel. Seed density increased with longitudinal distribution with more seeds occurring at the sites in the lower catchment than upper catchment. Managers should be aware that fire is needed to reduce the seed bank in both riparian and terrestrial fynbos systems. The cooler winter stack burns is the best option as it results in less destructive, lower temperatures that aids higher seedling recruitment. It is important to know the site history as age of dense infestation, number of fires and geology of site could influence seed bank density. In riparian systems the vertical distribution of seed is deeper than in the fynbos area. In order for clearing to be effective it is imperative that follow-up takes place and should be done prior to flowering to stop reseeding.

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Cilliers, Charl Daniel. "Post-fire effects of invasive exotic plants on seed banks, regeneration, soil chemistry and selected soil microbial populations in the Silvermine Nature Reserve, Cape Peninsula, South Africa". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53006.

Testo completo

Abstract (sommario):

Thesis (MSc) -- University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The fires, which occurred during January 2000 on the Southern Cape Peninsula, Cape Province, South Africa, focused attention on the importance of sound, informed management of exotic plant invaders in fynbos, especially at the urban interface. The fires also highlighted the relative lack of knowledge about the combined impacts of fire, exotic plants and the exotic-clearing programme on soil seed banks and regeneration. This study examines soil borne seed banks, regeneration, soil chemistry and micro biota in different postfire environments, focusing on three components of exotic plant management: The post-fire effects of standing invasive exotic plants; stacks of slashed exotic plant material which were deliberately burnt and stacks reduced to heat scars by a wildfire. The primary hypothesis addressed is that post-fire vegetation regeneration patterns, seed bank diversity and seed bank abundance are linked to pre-fire vegetation characteristics and, in particular, to the treatment of exotic plant species. It is also hypothesised that soil microbe population sizes are linked to pre-fire vegetation and soil chemical composition. Differences in soil seed banks, soil micro biota and vegetation regeneration patterns occur in different post-fire environments. High volumes of (live or dead) woody exotic biomass negatively impact upon postfire indigenous species diversity and abundance, both above and below-ground. Soil seed banks and above-ground regeneration decline with increasing fire intensity, wildfire burnt stack treatments showing the largest declines followed by wildfire burnt standing exotics, control burnt stacks, wildfire burnt cleared areas and wildfire burnt Mountain Fynbos treatments. Persistent indigenous seed banks are found under some exotic dominated stands. Heat damage, associated with high woody exotic biomass, affects seeds of all species into deep soil layers. Depth of burial is a more important determinant of seed survival during fires than seed size. Soil microbial populations are variably affected by exotic plants, their management and increases in fire intensity. The most drastic microbial population changes are in post-fire treatments of high exotic plant biomass. Soil chemistry affects microbial population sizes as does seasonal climatic changes. In this thesis vegetation, seed bank and microbial responses to various exotic plant management practices are shown and management recommendations are made. Keywords: exotic plants, fire, Fynbos Siome, microbes, post-fire succession, soil seed banks.
AFRIKAANSE OPSOMMING: Die Januarie 2000 vure op die Suid Kaapse Skiereiland het fokus gerig op die belangrikheid van goeie, ingeligte bestuur van uitheemse indringerplante in fynbos, veral naby stedelike gebiede. Die vure het ook 'n relatiewe .gebrek aan kennis aangaande die gekombineerde impakte van vuur, uitheemse plantegroei en indringer plant beheer programme op grond saadbanke en die hergroei van plante na 'n vuur aan die lig gebring. Hierdie projek bestudeer die invloed van vuur op grond saadbanke, hergroei van plante, grond chemie en mikro-organismes. Die klem lê op drie komponente van uitheemse plant bestuur: waar staande uitheemse plante voorkom; waar skoongekapte uitheemse plante in hope gestapel is en gekontraleerd gebrand is en waar soortgelyke hope in 'n onbeplande weghol vuur gebrand is. Die primêre hipotese is dat plant herstelpatrone, saadbank diversiteit en grootte gekoppel is aan veldtoestande voordat daar gebrand is, en veral aan die bestuur van uitheemse plantspesies. Nog 'n sentrale hipotese is dat die grootte van grond mikrobiale populasies gekoppel is aan veld toestande voor die brand en aan grond chemiese samestelling. Hierdie studie dui verskille aan in grond saadbanke, mikro-organismes en plant hergroeipatrone onder verskeie toestande na vuur. Die brand van hoë volumes (lewende of dooie) houtagtige uitheemse plant biomassa benadeel inheemse plant spesie diversiteit en getalle (bo en onder die grond oppervlak). Grond saadbanke neem af met vehogings in vuur intensiteit. Die grootste afnames is in wegholvuur gebrande gestapelde uitheemse plantmateriaal gevolg deur wegholvuur gebrande staande uitheemse plante, opsetlik gebrande hope uitheemse plante, gebrande skoongekapte areas en wegholvuur gebrande Berg Fynbos. Ou inheemse saadbanke is gevind onder sommige areas wat voor die vuur oorheers was deur uitheemse plantegroei. Hitteskade, geassosieer met hoë volumes houtagtige uitheemse biomassa, affekteer sade van alle spesies tot diep in die grond. Saad oorlewing tydens brande is meer geaffekteer deur diepte van begrawing in die grond as deur saad grootte. Grond mikro-organisme populasies is geaffekteer deur uitheemse indringer plante, die bestuur van uitheemse plante en vuur intensiteit. Die grootste veranderinge is waar die biomassa van uitheemse plantegroei baie hoog is. Grond chemiese samestelling en seisoenale veranderinge in weerspatrone affekteer die grootte van mikrobiale bevolkings. In hierdie tesis word verskille in plantegroei, saad store en grond mikrobes, soos geaffekteer deur uitheemse plant beheer programme uitgewys en voorstelle vir toekomstige bestuur gemaak. Sleutelwoorde: Fynbos Bioom, grond saad stoor, mikrobes, plant hergroei, uitheemse plante, vuur.

Gli stili APA, Harvard, Vancouver, ISO e altri

20

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.

Testo completo

Abstract (sommario):

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.

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Jayet, D. F. "An examination of observed climatic trends/changes over Banks Peninsula and the surrounding plains area, and their synoptic climatology". Thesis, University of Canterbury. Department of Geography, 1986. http://hdl.handle.net/10092/3866.

Testo completo

Abstract (sommario):

Rainfall and temperature data were collected over the study area (approximately 50 sites ), using all existing climatic records, to analyse observed climatic trends/changes since instrumental records began. These trends, using multiple regression analysis, were then compared to changes in synoptic flow patterns based on daily surface charts for the 1929 to 1985 period. Results indicate that changes in synoptic flow pattern have a very significant impact on rainfall and temperature trends. Observed rainfall trends tend to show cyclic trends or spells of wet and dry periods. Comparison with the literature suggests that some of the observed 10 year rainfall trends were related to the sunspot cycle, such as the winter rainfall trend. However changes in synoptic flow patterns appear to be the most important factor influencing rainfall trends. Temperature trends show a much stronger relationship with synoptic flow patterns than rainfall,particularly for maximum temperature trends. Wet periods over the study area are categorised by increased cyclonic activity in combination with increased southerlies and or, easterly circulations while dry periods are related to anticyclonic conditions and increased westerly circulation. Southerly, and to a lesser exent easterly circulations, have the most significant influence on temperature trends with a negative impact. The synoptic climatology of daily rainfall patterns over the study area indicated that the dominant rain-bearing winds come from the southerly quarter, especially southwesterly airflows. Higher rainfall probability and significant daily rainfall totals occur under cyclonic conditions in association with southerly to northeasterly airflows while anticyclonic west to northerly airflows produce the lower values.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Stewart, Simon Donald. "Using stable isotopes to trace the sources and fates of nitrate within mixed land-use catchments on the Banks Peninsula, New Zealand". Thesis, University of Canterbury. Biological Sciences, 2011. http://hdl.handle.net/10092/6711.

Testo completo

Abstract (sommario):

Increasing land-use change and land-use intensification over the last century has resulted in lotic systems being faced by an increasing intensity environmental. Potentially the most pervasive of these stressors is increased nitrogen runoff. However, understanding the affects of excess nitrogen (primarily nitrate) on lotic systems is severely complicated by the fact that multiple interacting stressors are associated with any given land-use and catchments will invariably contain multiple land-uses. Having analytical tools which can trace nitrogen as it is being cycled through the system is thus important for understanding the impacts of various land-uses on stream nitrogen-cycling. Stable isotopic analyses of δ¹⁵N and δ¹⁸O values within nitrate and δ¹⁵N and δ¹³C values within organic matter allow us to compare how nitrate in entering lotic systems and subsequently moving through them across multiple land-uses. In this study, I compared nitrate δ¹⁵N and δ¹⁸O and invertebrate δ¹⁵N and δ¹³C values within 35 streams across six land-uses (regenerating indigenous forest, horticulture, golf courses, dry stock agriculture, dairy agriculture and land invaded by exotic N-fixing legumes gorse (Ulex europaeus) and broom (Cytisus scoparius)) on the Banks Peninsula, New Zealand. Results showed that gorse and broom streams had significantly higher mean nitrate concentrations than all other land‐uses (mean NO₃-N = 1.02 ppm, P < 0.001). Furthermore, nitrate δ¹⁵N and δ¹⁸O values demonstrated that this elevated nitrate was being fixed by the plants themselves as opposed to a land-use legacy effect. Overall, native regeneration sites had significantly lower nitrate δ¹⁵N values than all other land-uses. Across all land-uses, except for regenerating indigenous forest, nitrate δ¹⁵N and δ¹⁸O values displayed positive covariation, indicative of biological fractionation. Results suggested that, at least within gorse and broom systems, this fractionation was primarily being driven by biological uptake as opposed to denitrification. However, the environmental parameters which had the greatest affects on these fractionation relationships differed substantially between land-uses suggesting that the factors controlling nitrate removal were specific to the land-use environment. Lotic invertebrate responses to land-use included a reduced dietary intake of coarse particulate organic matter (CPOM) across all sites relative to regenerating indigenous forest sites and a larger community trophic niche (range in δ¹³C values) in dairy and gorse sites relative to native regeneration and dry-stock sites. Land-use change lead to invertebrates having less CPOM available and subsequently feed on a wider range on trophic channels. However, no clear relationships were observed with these invertebrate trophic responses and individual land-use stressors (i.e. nitrate concentration or light availability), suggesting that trophic responses resulted from complex interactions between these stressors much in the same way these factors interacted to affect nitrate removal. Nonetheless, average δ¹⁵N values for the whole invertebrate communities were lower in regenerating indigenous forested sites than all other sites, indicating that land‐use induced changes to in-stream nitrogen cycling leaves a δ¹⁵N imprint on the invertebrate community. These findings have identified a significant novel source of nitrate within the regional landscape while also providing a uniquely holistic insight into the ways in which land-use impacts nitrogen cycling and community responses within lotic systems. Although these finding have highlighted the complexity associated with relationships between land-use and lotic systems responses, they also demonstrate how multiple stable isotopic proxies can elucidate vital mechanistic information. With more widespread data collection in New Zealand, in the future stable isotopic studies will be able to be a significant management and research tool for tackling the challenges faced by environmental practitioners in the 21st century.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Campbell, Kirsten L. "A study of home ranges, movements, diet and habitat use of kereru (Hemiphaga novaeseelandiae) in the southeastern sector of Banks Peninsula, New Zealand". Master's thesis, Lincoln University. Bio-Protection and Ecology Division, 2006. http://theses.lincoln.ac.nz/public/adt-NZLIU20080317.131118/.

Testo completo

Abstract (sommario):

The present study is part of the Kaupapa Kereru Programme. The main aim of the programme is to increase the numbers and range of kereru (Hemiphaga novaeseelandiae) on Banks Peninsula. Home ranges, movements, diet and habitat use of 15 kereru captured in Hinewai Reserve, Banks Peninsula, were investigated from February 2005 to February 2006. Hinewai Reserve is the largest tract of regenerating native forest in a highly modified urban-rural landscape. Phenology of 11 plant species predicted to be key kereru foods, was studied to determine the pattern of food availability in Hinewai Reserve. Twelve radio-tagged kereru resided in the Hinewai Reserve study site (Otanerito Valley and Sleepy Bay) and three resided in Akaroa. Ripe fruit was available from January to August; the height of the fruiting season was in autumn. The bulk of new leaf growth occurred in spring and early summer although new leaves were available on broom and tree lucerne year round. Peak flowering occurred in spring. Kereru in Akaroa ate a total of 21 plant species; six of these species were native and 15 introduced. Kereru in the Hinewai Reserve study site ate a total of 26 plant species; 20 of these species were native and six introduced. Fruit was preferred when readily available. Native fruit appeared to be preferred over fruit of introduced species in Akaroa, where both types were available. New foliage of introduced legumes and deciduous species appeared to be preferred over new foliage of native species at both sites during winter and spring. These species were important food sources prior to the breeding season and may be selected specifically for their nitrogen and protein content. Food is currently not a limiting factor for kereru survival or reproductive success. Considerable variation in the use and preference of vegetation types of individual kereru made it difficult to identify trends in habitat selection. Use and preference for many vegetation types was seasonal; this was certainly because of the availability of food species included in or close to these vegetation types. Overall, native vegetation communities were used more than communities dominated by introduced species and forest communities were used more than non-forest communities. Kanuka (Kunzea ericoides) was used most often for non-feeding activities and 67% of observed nests were built in kanuka. Annual home ranges and core areas in the Hinewai Reserve study site (mean of 15.9 and 2 ha respectively) were significantly larger than those found in Lyttelton Harbour, Banks Peninsula in previous research (mean of 8 and 0.08 ha respectively). Home ranges were larger when fruit was eaten, than when no fruit was eaten indicating that kereru are more sedentary when feeding on foliage. Kereru from the Hinewai Reserve study site made no excursions >5 km and no daily movements >2 km. Kereru from Akaroa and Sleepy Bay travelled into Otanerito Valley to feed on horopito in autumn, indicating that there may have been a lack of fruit in their local areas during autumn. No kereru in Otanerito Valley travelled outside of the valley. The distribution of high quality food sources is likely to have caused the observed differences in home range and core area size between localities. Kereru in Lyttelton Harbour may have been restricted to small patches of high quality resources in a study area consisting largely of unsuitable habitat. In Hinewai Reserve, high quality resources were spread over larger areas and were more uniformly distributed. The density of kereru was unknown at both study sites, and this confounded assessment of habitat quality. However, it is likely that the Hinewai Reserve study site would support a higher number of kereru. The main factor limiting population growth in the present study was failure of nests at the egg and chick stage. The fledge rate was 17%. Two of fifteen adult kereru died. Control of predators should be the first aspect of management that is focused on, and will almost certainly increase reproductive success of kereru and loss of breeding adults. As the population of kereru on Banks Peninsula increases due to predator control in existing kereru habitat, food may become a limiting factor. Habitat can be improved for kereru by planting a diverse range of plant species that provide food year-round. Native fruiting species are greatly recommended for habitat enhancement and should be selected so that fruit is available for as much of the year as possible. Native and introduced legumes should also be made available as foods for winter and spring. As most land on Banks Peninsula is privately owned, co-operation and enthusiasm of the community is critical for successful management. Information and support needs to be given to landowners wishing to enhance their properties for kereru.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Rayment, William J., e n/a. "Distribution and ranging of Hector�s dolphins : implications for protected area design". University of Otago. Department of Marine Science, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090227.161621.

Testo completo

Abstract (sommario):

The efficacy of a Marine Protected Area (MPA) is contingent on it having a design appropriate for the species it is intended to protect. Hector�s dolphin (Cephalorhynchus hectori), a coastal delphinid endemic to New Zealand, is endangered due to bycatch in gillnets. Analyses of survival rate and population viability suggest that the Banks Peninsula population is most likely still declining despite the presence of the Banks Peninsula Marine Mammal Sanctuary (BPMMS), where gillnetting is regulated. More data on distribution and movements of dolphins are therefore required to improve the design of the BPMMS. On aerial surveys of Hector�s dolphin distribution at Banks Peninsula over three years, sightings were made up to 19 n.mi. offshore. On average, 19% of dolphins were sighted outside the BPMMS�s 4 n.mi. offshore boundary in summer, compared to 56% in winter. On similar surveys of the South Island�s west coast, all dolphins were sighted within 6 n.mi. of the coast and there was no seasonal change in distribution. At each location, Mantel tests indicated that distance offshore had the strongest and most consistent effect on distribution. However, a logistic regression model using the combined datasets suggested that distribution was most strongly defined by water depth, with all sightings made inside the 90 m isobath. Boat surveys were carried out at Banks Peninsula (2002 to 2006) to continue the long-term photo-ID project. Using the 22 year dataset, alongshore home-range of the 20 most frequently sighted dolphins was estimated by univariate kernel methods. Mean alongshore range was 49.69 km (SE = 5.29), 60% larger than the previous estimate. Fifteen percent of these individuals had ranges extending beyond the northern boundary of the BPMMS. An acoustic data logger, the T-POD, was trialled for passive acoustic monitoring of Hector�s dolphins. Simultaneous T-POD/theodolite surveys revealed that T-PODs reliably detected dolphins within 200m. No detections were made beyond 500m. To monitor inshore habitat use, T-PODs were deployed in three locations at Banks Peninsula (n = 431 days). A GLM analysis of Detection Positive Minutes (DPM) per day indicated that season had the largest effect on detection rate, with over twice as many DPMs per day in summer (x̄ = 99.8) as winter (x̄ = 47.6). The new findings on Hector�s dolphin distribution and ranging can be used to improve the design of the BPMMS. It is recommended that the offshore boundary of the BPMMS is extended to 20 n.mi. (37 km), the northern boundary is moved 12 km north and recreational gillnetting is prohibited year round. In areas where distribution of Hector�s dolphin has not been studied, the offshore boundary of MPAs should enclose the 100 m isobath.

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Clement, Deanna Marie, e n/a. "Distribution of Hector�s dolphin (Cephalorhynchus hectori) in relation to oceanographic features". University of Otago. Department of Zoology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070221.122411.

Testo completo

Abstract (sommario):

Hector�s dolphin (Cephalorhynchus hectori) is an endangered coastal species endemic to New Zealand. Their distribution, like other marine organisms, is intertwined with the dynamics of their local habitats, and at a larger scale, the coastal waters around New Zealand. The main purpose of this thesis was to identify specific habitat requirements of this rare dolphin. Hector�s dolphin distribution around the South Island was quantified along several temporal and spatial scales. Large-scale density analyses of abundance surveys found over half of the South Island�s current population occurred within only three main regions. Two of these strongholds are along the west coast and the third is located around Banks Peninsula on the east coast. Smaller-scale analyses at Banks Peninsula found the majority of the dolphin community was preferentially using core regions within the marine mammal sanctuary. Monthly surveys showed that in summer and autumn statistically more dolphins occurred within inshore regions ([less than or equal to]one kilometre), spread throughout the surveyed coastline. From May through winter, dolphin densities rapidly declined. Remaining dolphins were significantly clumped in more offshore waters of eastern regions. The lowest encounter rates occurred between August and September. Certain 'hotspots' consistently had higher dolphin densities throughout the study period while others were preferred seasonally. To address habitat preferences, surveys simultaneously collected oceanographic samples using a CTD profiler. In general, physical variables of the Peninsula�s eastern and southeastern waters varied less, despite being regularly exposed to upwellings and the varied presence of sub-tropical waters. Semi-sheltered bays and shallow inshore waters were highly variable and more susceptible to spatially discrete influences, such as localised river outflows and exchange events. Several hydrographic features were seasonally predictable due to their dependence on climate. The stratification and location of the two dominant water masses (neritic and sub-tropical) accounted for over half of the temporal and spatial variability observed in oceanographic data. Possible relationships between oceanographic features and aggregations of dolphins within Banks Peninsula were examined using global regression and a spatial technique known as geographical weighted regression (GWR). GWR models out-performed corresponding global models, despite differences in degrees of freedom and increased model complexity. GWR results found relationships varied over localised scales that were concealed by global methods. Monthly GWR models suggested the seasonal presence and strength of local oceanographic fronts influenced dolphin distribution. Dolphin aggregations coincided with the steepest gradients between water masses along eastern regions of the Peninsula, and strong exchange events along the edges of the study area. The continued survival of this endangered species is contingent on its protection. Long-term monitoring programmes are needed for the three main strongholds identified in this study. The occurrence of Hector�s dolphin 'hotspots' along frontal zones within Banks Peninsula also suggests alternative and increased protection strategies are needed for this sanctuary to be effective. In light of this thesis� findings and based on marine protection research, future sanctuaries need to consider why Hector�s dolphins are preferentially using particular regions and how their association with certain oceanographic features can help make informed decisions on more appropriate protected areas.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Hartung, Eva. "Early magmatism and the formation of a ‘Daly Gap’ at Akaroa Shield Volcano, New Zealand". Thesis, University of Canterbury. Geological Sciences, 2011. http://hdl.handle.net/10092/5584.

Testo completo

Abstract (sommario):

The origin of compositional gaps in volcanic deposits remains controversial. In Akaroa Volcano (9.6 to 8.6 Ma), New Zealand, a dramatic compositional gap exists between basaltic and trachytic magmas. Previously, the formation of more evolved magmas has been ascribed to crustal melting. However, the interpretation of new major and trace element analysis from minerals and bulk-rocks coupled with the mechanics of crystal-liquid separation offers an alternative explanation that alleviates the thermal restrictions required for crustal melting models. In a two-stage model, major and trace element trends can be reproduced by polybaric crystal fractionation from dry melts (less than 0.5 wt.% H2O) at the QFM buffer. In the first stage, picritic basalts are separated from an olivine-pyroxene dominant mush near the crust-mantle boundary (9 to 10 kbar). Ascending magmas stagnated at mid-crustal levels (5 to 6 kbar) and fractionated an olivine-plagioclase assemblage to produce the alkali basalt-hawaiite trend. In the second stage, trachyte melt is extracted from a crystal mush of hawaiite to mugearite composition at mid-to-upper crustal levels (3 to 5 kbar) after the melt has crystallised 50 vol.%. The fractionated assemblage of plagioclase, olivine, clinopyroxene, magnetite, and apatite is left in a cumulate residue which corresponds to the mineral assemblage of sampled ultramafic enclaves. The results of trace element modelling of Rayleigh fractionation using this extraction window is in close agreement with the concentrations measured in trachyte (= liquid) and enclaves (= cumulate residue). The compositional gap observed in the bulk-rock data of eruptive products is not recorded in the feldspar data, which show a complete solid solution from basalt and co-magmatic enclaves to trachyte. Complexly zoned plagioclases further suggest episodical magma recharge events of hotter, more mafic magmas, which lead to vigorous convection and magma mixing. In summary, these models indicate that the Daly Gap of Akaroa Volcano formed by punctuated melt extraction from a crystal mush at the brittle-ductile transition.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Eriksen, Kirstie. "The structures, playing techniques and teaching methods of four community brass bands in the Cape Peninsula". Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12003.

Testo completo

Abstract (sommario):

Includes abstract.
Includes bibliographical references.
The objectives of this study are to investigate the teaching methods embedded in the oral transmission of music knowledge, the musicians’ playing technique, the cultural and social benefits of music in the communities of the four bands, as well as to look at the advantages and disadvantages of aural and oral modes of transmission of knowledge in teaching.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Soto, Ramos Inia Mariel. "Harmful Algal Blooms of the West Florida Shelf and Campeche Bank: Visualization and Quantification using Remote Sensing Methods". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4775.

Testo completo

Abstract (sommario):

Harmful Algal Blooms (HABs) in the Gulf of Mexico (GOM) are natural phenomena that can have negative impacts on marine ecosystems on which human health and the economy of some Gulf States depends. Many of the HABs in the GOM are dominated by the toxic dinoflagellate Karenia brevis. Non-toxic phytoplankton taxa such as Scrippsiella sp. also form intense blooms off the Mexican coast that result in massive fish mortality and economic losses, particularly as they may lead to anoxia. The main objectives of this dissertation were to (1) evaluate and improve the techniques developed for detection of Karenia spp. blooms on the West Florida Shelf (WFS) using satellite remote sensing methods, (2) test the use of these methods for waters in the GOM, and (3) use the output of these techniques to better understand the dynamics and evolution of Karenia spp. blooms in the WFS and off Mexico. The first chapter of this dissertation examines the performance of several Karenia HABs detection techniques using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images and historical ground truth observations collected on the WFS from August 2002 to December 2011. A total of 2323 in situ samples collected by the Florida Fish and Wildlife Research Institute to test for Karenia spp. matched pixels with valid ocean color satellite observations over this period. This dataset was used to systematically optimize variables and coefficients used in five published HAB detection methods. Each technique was tested using a set of metrics that included the F-Measure (FM). Before optimization, the average FM for all techniques was 0.47. After optimization, the average FM increased to 0.59, and false positives decreased ~50%. The addition of a Fluorescence Line Height (FLH) criterion improved the performance of every method. A new practical method was developed using a combination of FLH and Remote Sensing Reflectance at 555 nm (Rrs555-FLH). The new method resulted in an FM of 0.62 and 3% false negatives, similar to those from more complex techniques. The first chapter concludes with a series of recommendations on how to improve the detection techniques and how to take these results a step further into a Gulf wide observing systems for HABs. In chapter two, ocean color techniques were used to examine the extension, evolution and displacement of four Karenia spp. events that occurred in the WFS between 2004 and 2011. Blooms were identified in the imagery using the new Rrs-FLH method and validated using in situ phytoplankton cell counts. The spatial extension of each event was followed in time by delineating the blooms. In 2004 and 2005, the WFS was affected by a series of hurricanes that led to high river discharge and intense sediment resuspension events. Both processes had an impact on HAB occurrence. For example, I tracked a Karenia spp. bloom found in late December 2004 approximately 40-80 km offshore Saint Petersburg, which then expanded reaching an extension of >8000 km2 in February 2005. The bloom weakened in spring 2005 and intensified again in summer reaching >42,000 km2 after the passage of hurricane Katrina in August 2005. This bloom covered the WFS from Charlotte Harbor to the Florida Panhandle. Two other cases were studied in the WFS. The results of the Hybrid Coordinate Ocean Model from the U.S. Navy aid understanding the dispersal of the blooms. During fall 2011, three field campaigns to study HABs in Mexico were conducted to do an analysis of optical properties and explore the possibility of using ocean color techniques to distinguish between the main phytoplankton blooms in that region. Three main bloom scenarios were observed in the Campeche Bank region: massive diatom blooms, blooms dominated by Scrippsiella spp., and Karenia spp. blooms. The normalized specific phytoplankton absorption spectra were found to be different for Karenia spp. and Scrippsiella sp. blooms. A new technique that combines phytoplankton absorption derived from MODIS data and the new technique developed in Chapter One showed potential for a detection technique that can distinguish between Karenia and Scrippsiella blooms. Additional work is needed to improve the new technique developed for Mexican waters, but results show potential for detection techniques that can be used Gulf-wide. This will help better understand the dynamic and possible connectivity of phytoplankton blooms in the GOM.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Fraser, Iain A. "The effects of forest fragmentation on stream invertebrate communities on Banks Peninsula : a thesis submitted for partial fulfilment for the degree of Master of Science in Zoology at the University of Canterbury /". 2006. http://library.canterbury.ac.nz/etd/adt-NZCU20070313.151545.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Banks Peninsula"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili