Antarctic Theses

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Capturing the value of biosurveillance “big data” through natural capital accounting
(Journal Article, Informa UK Limited, 2021) Castle, David; Hebert, Paul D. N.; Clare, ,Elizabeth L.; Hogg, Ian D.; Tremblay, Crystal
Global biodiversity is in crises. Recognition of the scale and pace of biodiversity loss is leading to rapid technological development in biodiversity science to identify species, their interactions, and ecosystem dynamics. National and international policy developments to stimulate mitigation and remediation actions are escalating to meet the biodiversity crises. They can take advantage of biosurveillance “big data” as evidence for more sweeping and impactful policy measures. The critical factor is translating biosurveillance data into the value-based frameworks underpinning new policy measures. An approach to this integration process, using natural capital accounting frameworks is developed.
Resilience of microbial mats in Antarctic ponds to climate-relevant environmental disturbance
(Thesis, The University of Waikato, 2021) Mills, Francesca
Continental Antarctica is a cold desert, where the hydrologic system is dependent on melting of snow and ice. In a warming climate it is projected that there will be a significant change in precipitation, evaporation, cloud formation, all affecting the ice-water dynamic. Hydrology is considered vulnerable to climatic change. Hydrological change cascades through the environment affecting Antarctic ponds which are important centres for inland microbial biodiversity. An understanding of community vulnerability to anticipated change can be developed through assessing organism and functional resilience to climate-related and other forms of disturbance. The aim of this study is to identify the effects of disturbance on microbial communities, specifically cyanobacterial mats, with a particular focus on changes that may occur resultant to anthropogenic climate change. This study undertook three experiments, which identified impacts of disturbance on three key cyanobacterial mat functions – nitrogen fixation, photosynthesis/respiration, and recovery after a physical disturbance. Sampling was undertaken in the McMurdo Ice Shelf (MIS) meltwater ponds in late January 2019. The design for the nitrogen fixation experiment used a natural gradient of conductivity across five ponds (Fresh, Casten, P70, Brack and Salt) in a space-for-time approach that compared microbial composition and nitrogen fixation rates. The light disturbance study completed in New and P70 ponds tested mat ability to retain photosynthesis and respiration under a pulsed disturbance – covering microbial mats with shade cloth for 12 months. In this study the light-photosynthesis response and mat composition were analysed when shaded and not shaded (control plots). The third experiment examined short-term response to physical disturbance by observing the recovery of mat structure and community composition for 2 years was also completed in New and P70 ponds. It was identified that there was no significant change in acetylene reduction (as a proxy for nitrogen fixation) over the salinity range. Acetylene reduction ranged between 22.4 ± 3.4 µMol/m²/h in Brack Pond (conductivity = 10.5 mS/cm) and 49.6 ± 17.1 µMol/m²/h in Casten Pond (conductivity = 2.3 mS/cm). The acetylene reduction difference was statistically significant between Brack Pond and Casten Pond (F = 0.006 (Bonferroni Correction significance of F ≤ 0.01)). Microbial mat composition changed across the conductivity gradient, but significant proportions of different N-fixing and mat-forming genera were evident along the salt gradient, suggesting functional resilience through species turnover. It was also identified that when receiving a 95-96% decrease in ambient light photosynthetic bacteria were able to maintain photosynthesis and respiration at similar rates within the microbial mats. However, in shaded plots the maximum net oxygen production occurred at an average irradiance between 350 – 450 µMol photons m-²s-¹ and was inhibited at higher levels. In control plots the maximum net oxygen production was ≥900 µMol photons m-²s-¹. In control samples net photosynthesis exceeds zero (photosynthesis exceeds respiration) at ~275 µMol photons m-²s-¹, in shaded samples this occurred at ~100 µMol photons m-²s-¹. Rapid shifts in the appearance of mats under, and after shading led to the conclusion that the acclimation may be based on vertical migration of cyanobacteria within the mats, which showed no significant changes in relative abundance of taxa. After physical removal of microbial mat, communities were shown to reform to similar relative abundances as control samples within two years of the disturbance, within this experiment a successional change in species abundance was observed. This research highlights the resilience of microbial mat populations on the MIS to the types of change that are anticipated to accompany climate change. It supports conclusions previously identified that cyanobacterial mats are functionally resilient to short-term and long-term disturbances. Ongoing research will improve the knowledge on the resilience of other functions required in these environments.
An investigation of microbial communities across two extreme geothermal gradients on Mt. Erebus, Victoria Land, Antarctica
(Thesis, The University of Waikato, 2021) Smith, Emily
The geothermal fumaroles present on Mt. Erebus, Antarctica, are home to numerous unique and possibly endemic bacteria. The isolated nature of Mt. Erebus provides an opportunity to closely examine how geothermal physico-chemistry drives microbial community composition and structure. This study aimed at determining the effect of physico-chemical drivers on microbial community composition and structure along extreme thermal and geochemical gradients at two sites on Mt. Erebus: Tramway Ridge and Western Crater. Microbial community structure and physico-chemical soil characteristics were assessed via metabarcoding (16S rRNA) and geochemistry (temperature, pH, total carbon (TC), total nitrogen (TN) and ICP-MS elemental analysis along a thermal gradient 10 °C–64 °C), which also defined a geochemical gradient. Diversity increased in alkaline soils suggesting pH to be the primary driver of microbial community structure across the gradients. Archaea dominated the microbial communities at Tramway Ridge compared to Western Crater, which was dominated by Bacteria. Western Crater has been sampled for the first time, widening the understanding of geothermal sites on Mt. Erebus. Organisms that were once considered cosmopolitan may not be as cosmopolitan as expected in Antarctica. These organisms may require specific niches that allow them to colonise new habitats. This study also showed that gathering more samples from Tramway Ridge has widened understanding of the changing environments that microbial communities on Mt. Erebus live in. The study provides a foundation on which to compare microbial and geochemical interactions across all geothermal sites within Victoria Land. This supports the effect of specific geothermal characteristics of the fumaroles in manipulating the microbial communities present.
Origin of palaeo proglacial lake sediments in Taylor Valley, Antarctica
(Thesis, The University of Waikato, 2005) Milicich, Sarah
The origin of carbonates found at three locations in the Taylor Valley and their association with different glacial advances is presented. Samples were collected from three locations through the Taylor Valley, specifically Nussbaum Riegel west of Lake Fryxell, Sollas Bench on the slopes above Lake Bonney, and from Pearse Valley. Carbonates were collected primarily from the surficial glacial sediment, though at one site at Nussbaum Riegel a pit indicated the stratigraphy contained multiple carbonate horizons. The carbonate from Nussbaum Riegel was in situ, while at the other two sites the carbonate was incorporated into moraines. The oxygen isotope values indicate that carbonates were deposited in lakes with two different origins. δ¹⁸ values of approximately -28% to -32% for the Nussbaum Riegel carbonate samples indicate "Glacial Lake Nussbaum" likely formed during glacial conditions when grounded ice expanded in McMurdo Sound pushing a lobe of ice up the mouth of the Taylor Valley. δ¹⁸ values of approximately -33 %to 38% for carbonate samples from Pearse Valley and Sollas bench indicate that "Glacial Lake Pearse" and the proglacial lake in which the Sollas Bench carbonates were deposited would have formed during interglacial conditions. It is proposed that an expanded Taylor Glacier was advancing though its own proglaical lakes, reworking carbonate sediment deposited in the lakes. The carbon isotopes reflect the nature of the carbon dioxide cycling within the lakes. Strongly positive δ¹³C values are interpreted as reflecting low temperature equilibrium with atmospheric carbon dioxide or freezing processes causing precipitation. The trace element chemistry of the carbonates is inferred to indicate that the origin of their composition is primarily controlled by the composition of the precipitating fluid and the mineralogy of the carbonate. Samples containing higher proportions of aragonite have higher concentrations of the larger ions such as barium and strontium, while those with more calcite in the mineral structure contain more of the smaller ions such as magnesium. XRD analyses indicate that the Nussbaum Riegel carbonate samples are a mix of dominantly aragonite with some calcite. SEM images of the carbonate crystals show that they are cementing detrital material. Petrographic analysis of the Nussbaum Riegel carbonates indicate that much of the detrital material is volcanic in nature and was likely sourced from the McMurdo Volcanics. The Sollas Bench and Pearse Valley carbonate samples are predominantly aragonite as shown by XRD analyses. SEM images show the crystals in these samples are a mix of radiating needles and randomly oriented needles, pointing to two different processes during precipitation. SEM images also showed the presence of halite within the carbonate samples. The Nussbaum Riegel carbonates are inferred to have been deposited during periods of lake level fluctuation, where draining of ground water towards a lower lake level resulted in evaporation at the lake margins and cementation of the surficial sediment. The Sollas Bench and Pearse Valley carbonates were likely deposited under a regime of water removal, either via evaporation or freezing, making these carbonates a mix of evaporites and "cryorites". Cryorite is a new term, being defined as deposits precipitated as a result of concentration by removal of water due to freezing. In this case they appear to be primarily "cryorites". Halite was identified within many of the carbonate samples and gypsum was found associated with them. This suggests that there was a strongly concentrated brine present at the time of precipitation. The source of the salt in the western end in the Taylor Valley is likely to be an evaporate sequence in a subglacial depression indicated on subglacial profiles, currently being overridden by Taylor Glacier. The evaporites could have deposited during a warmer period when the Ferrar Valley was a fjord. Seawater would then have overflowed into Taylor Valley at its convergence with the Ferrar Valley. The resulting lakes then evaporating in the deep depression. Salts are currently being reworked into the valley, a similar situation is proposed for the Sollas Bench carbonates
Microbial diversity in relation to human activity in historic areas of Ross Dependency, Antarctica
(Thesis, The University of Waikato, 2003) Minasaki, Ryuji
The goal of this study was to undertake a relatively broad microbiological investigation at historic areas of Cape Evans and Ross Island. The two phylogenetically diverse targets were Bacillus anthracis, the causative agent for anthrax disease, and filamentous micro-fungi associated food products. The human activities were presumed to have played a significant contribution to the introduction of non-indigenous Bacillus anthracis and many filamentous micro-fungi at the historic areas on Ross Island. Bacillus anthracis was suspected to be present at Cape Evans based on a circumstantial clinical analysis of the death of the member in Captain Robert F Scott's Terra Nova Expedition in 1912. Detection methods based on polymerase chain reaction (PCR) targeting B. anthracis specific genes on chromosome and two plasmids were employed. DNA extraction was performed by a bead-beating technique from 74 environmental samples. PCR efficiency was compromised probably due to inhibitors in DNA extracts, but improved with higher concentrations of Taq polymerase. Initially a total of 74 environmental samples were screened with one set of primers before positively tested 19 samples were rigorously investigated with seven sets of primers. Nested PCR also increased the target specificity and detection levels. Sequence analyses of the several positive samples from PCR reactions were characteristic to B. anthracis. A diverse range of filamentous micro-fungi were isolated on three different media at two different temperatures, 15 °C and 25 °C, and identified by classical morphological taxonomy from the foodstuffs and internal environmental samples of Captain Robert F Scott's historic hut at Hut Point built in 1901. In total, there were 22 taxa and 14 genera recorded including many cosmopolitan species isolated from the samples, in particular Penicillium species. An extensive literature review of the :filamentous micro-fungi found in Antarctica identified that 7 taxa isolated in the study were not reported previously. Many isolates were obtained at 15 °C while some isolates grew in the presence of antibiotics.
A Sedimentological and Micropaleontological Study of Quaternary Sections of Cores from the New Zealand Sector of the Southern Ocean
(Thesis, The University of Waikato, 1998) Mackie, Jon
The Southern Ocean lies between the Subtropical Front (STF) at about 45⁰S latitude and the continental landmass of Antarctica. It plays an important role in global climatic and oceanic circulation patterns, and is responsible for production of most water characteristics below the thermocline. The New Zealand sector of the Southern Ocean (NZSSO) is situated in a unique position to study past changes in oceanic circulation and climate from the record preserved in deep-sea sediment cores. Using piston cores collected from water depths of 461-5100 m by USNS Eltanin during 1968-1972, a sedimentological, micropaleontological, and stable oxygen and carbon isotope study, including some radiocarbon dating, has been conducted on the upper 1 m of sediment in 12 cores spanning a latitudinal transect from 52°S to 61°S south of New Zealand. The transect crosses the modem position of the Subantarctic Front (SAF) at ∼56°S and extends as far as the Antarctic Polar Front (AAPF) at ∼63°S. The study has shown the NZSSO cores must be viewed as two subgroups. The cores are divided at the SAF into a northern subgroup (north of the SAF) and a southern subgroup (south of the SAF) on the basis of sedimentary lithologies, textures, composition and depositional histories. The northern cores are located in the vicinity of the southern margin of Campbell Plateau and are all highly calcareous ( ∼95% ), being composed of planktic and benthic foraminifera and nannofossils with minimal terrigenous material content. The northern cores include two textural facies controlled by the dominant biogenic sediment. Facies A, a muddy sand, is dominated by the Subantarctic foraminiferal assemblage of Globigerina bulloides, Neogloboquadrina pachyderma (sinstral and dextral), Globigerinita spp., Globorotalia injlata and Globorotalia truncatulinoides. Facies B, a sandy mud, is dominated by calcareous nannofossils, especially Emiliania huxley, Coccolithus spp., and Calcidiscus spp. The southern subgroup of cores lies in the Southwest Pacific Basin and are dominated by biogenic siliceous material and common (11-27%) terrigenous material. They belong to Facies C, a sandy silt, composed mainly of silt-sized frustules of diatomsand nassellaria radiolaria and terrigenous material (quartz, plagioclase feldspars, biotite and muscovite). Where calcareous material exists south of the SAF it is composed of an Antarctic foraminiferal assemblage involving Neogloboquadrina pachyderma (sinstral),Globigerina bulloides and Globorotalia injlata. All foraminifera of the Antarctic assemblage show evidence of dissolution. The northern subgroup of cores lies in an average water depth of 1200 m, while south of the SAF the average water depth of the cores is 4700 m. The lysocline for the NZSSO is determined at ∼3200-4100 m, with a carbonate compensation depth (CCD) of 4800 m. Any calcareous material south of the SAF is actively being affected by dissolution which biases the sedimentary record of the southern subgroup of cores to dissolution resistant organisms (diatoms and radiolaria) and terrigenous material. The stable isotope records for the northern NZSSO cores show only a 0.8% shift between inferred glacial and interglacial conditions. Smoothing of the record may be due to bioturbation and/or to extensive sediment reworking by bottom currents, forming rather condensed sedimentary records, especially during glacial periods. Oxygen isotope stages back to stage 5 have been suggested in one core (36-42); this places the Last Glacial-Holocene transition at ∼7 cm, stage 2/3 boundary at ∼21 cm, stage 3/4 boundary at ∼65cm, and a possible stage 4/5 boundary at ∼95 cm downcore. The position of the Last Glacial and stage 2/3 boundary are confirmed by radiometric dates obtained from the same northern core: 19,120 +/- 110 yrs BP at 10 cm downcore and 23,900 yrs +/- 200 yrs BP at 20 cm downcore. Faunal changes in the benthic foraminifera occur near the glacialinterglacial transitions from Globocassidulina subglobosa-dominated during glacial periods to common Epistominella exigua during interglacials. Textural facies also show changes near these transitions, with Facies A characterising glacial periods and Facies B during interglacial periods. Associated with changes in texture are colour changes which allow the correlation of the glacial-interglacial transitions across many of the northern cores. The Last Glacial situation cannot be determined uniquely for the southern subgroup of cores as they have, to varying degrees, experienced extensive erosion and reworking during the Late Quaternary or earlier. Collectively, the data suggest there has not been significant change in oceanic paleoenvironmental conditions north of the SAF, immediately south of New Zealand, between glacial and interglacial periods. This could be because the topographic high marking the southern edge of the Campbell Plateau has essentially fixed the SAF, irrespective of oceanic climatic conditions. The topographic lock would be further enhanced by sea level drops of ∼120 m during glacial periods. In contrast, east and west of New Zealand in open water conditions evidence from other studies indicates major northward shifts in the position of both the SAF and the AAPF. The limited variation downcore in the abundances of sinistrally coiled Neogloboquadrina pachydenna, the small shifts in the stable oxygen isotope record, and the lack of change in faunal assemblages together suggest that ranges in the sea surface temperature change between glacial and interglacial periods at higher latitudes were probably not so severe as at intermediate latitudes. Due to the relatively small temperature changes between glacial and interglacial conditions at higher latitudes the faunal and isotopic indicators may only record extreme events.
An investigation of soil moisture associated with ephemeral streams, Wright Valley, Antarctica
(Thesis, The University of Waikato, 2005) Shanhun, Fiona L.
Ephemeral streams in Wright Valley, Antarctica, are fed by glacial melt and flow for between four and ten weeks annually. Hyporheic zones develop concomitantly with ephemeral stream channels. These zones are areas of saturated or moistened soil, depending on their proximity to the stream. The hyporheic zones are laterally extensive, and may represent a greater proportion of total meltwater than surface water in the stream channel, thus exacerbating the risk of accidental contamination of streams. The hydrological system in Wright Valley is closed, with streams flowing inland to Lake Vanda via the Onyx River. This study aimed to quantify the extent to which liquid moisture was present in soils associated with Goodspeed Stream, in order to better predict the vulnerability of stream margins to impacts of human activities. Soil samples were collected from transects across the Goodspeed lower alluvial fan and analysed for gravimetric moisture content, electrical conductivity, and particle size distribution. A pedotransfer function was used to estimate soil moisture potential in order to show the direction of water movement across the lower alluvial fan. Climate data including air temperature, soil temperature, and total solar radiation were measured; stream flow in Goodspeed Stream was estimated. The Goodspeed Stream near-stream and extended hyporheic zones were identified. Distal components of the hyporheic zone were also identified at distances of up to 7 4 m from Goodspeed Stream. Soil gravimetric moisture content increased with soil depth and proximity to Goodspeed Stream. Distal components of the hyporheic zone observed at distances of 21, 59 and 74 m from Goodspeed Stream had relatively high gravimetric moisture contents (up to 7%; 88 in visibly dry soils was 0.6%). The distal hyporheic zones have the potential to develop into flowing stream channels during periods of increased melt. Soil electrical conductivity ranged from 34 - 10520 μSiem. Salts precipitated at the soil surface were concentrated at the western-most edge of the extended hyporheic zone and on raised bar features across the fan, highlighting zones of movement and evaporation of soil moisture. The particle size distribution of the <2 mm fraction was relatively uniform across the fan, being dominated by medium sand (45%). Soil moisture potential decreased with distance from Goodspeed Stream, indicating that small spills occurring outside the extended hyporheic zone would be driven laterally across the fan, away from the stream. Spills within the extended hyporheic may be incorporated into Goodspeed Stream. Large spills anywhere on the Goodspeed lower alluvial fan would migrate downwards to ice cement before flowing down-slope under gravity towards the Onyx River. Areas vulnerable to accidental spills and physical disturbance were highlighted on oblique photographs. Three vulnerability zones were identified based predominantly on the observed extent and movement of soil moisture. Zone 1 designates stream channels or surface waters and near-stream hyporheic zones, Zone 2 encompasses extended hyporheic zones, while Zone 3 applies to soils of alluvial fans, including distal hyporheic zones. Recommendations were made as to the types of activities permissible in each of the three zones.
Development and application of a method for U-Th dating of the Bonney Drift, Taylor Valley, Antarctica
(Thesis, The University of Waikato, 1991) Smith, David W.
The lacustrine carbonates of the Bonney Drift, Taylor Valley, Antarctica were deposited in lakes proglacial to glaciers advancing through the valley, and now occur as lag and clasts in the glacial drift formed by the glacier. They commonly contain 8 to 25% detritus, including high levels of silica, titanium, iron, manganese, and other elements; making the extraction and purification of uranium and thorium problematic. A standard U-Th dating process was adapted to deal with the technical problems peculiar to the samples dated. Silica often formed a gel at the head of the U-Th separation column, and was removed using HF. Titanium frequently precipitated out during the conversion of the thorium fraction from a HCl matrix to HNO₃ form (used for further ion exchange purification) causing very low thorium recovery. This was overcome by using much higher volumes during conversion. The uranium eluate from the separation column often contained high levels of iron and manganese. These were removed on a small ion exchange column in HNO₃. The resin and wash volumes were adjusted to allow iron and manganese to wash off, but allowing the uranium to be held and eluted subsequently. An electrodeposition method was developed to achieve the thin plates necessary for alpha spectroscopy. Silver cathode discs were used in a teflon plating cell, with a stirrer rotating on the spiral planar platinum anode. An NH₄Cl/HCl electrolyte was used, adjusted in pH after sample uptake. Of the 62 samples successfully dated, 13 were eliminated for such reasons as low resolution and spectral shift; leaving 17 duplicates, one triplicate and 12 single analyses for further consideration. Samples with low ²³²Th/TIFFS Th levels were corrected for detrital ²³²Th addition. The dates obtained were considered in terms of age, geographic distribution, and uranium isotope ratios and concentrations. δ180 suggested that samples were derived from either Taylor Glacier meltwaters, or possibly Ross Ice Sheet Stage 6 meltwaters, and showed that δ180 values in the meltwaters increased towards the middle of each event. Three major events were identified. (i) an extensive period of deposition around 240 to 300kA (Stage 9?), This may possibly represent two events, in a lake(s) most likely formed proglacial to an expanded Taylor Glacier. (ii) a short period of lacustrine conditions around 175 to 190 kA ago, correlated with either Taylor Glacier expansion at the end of Stage 7, or Ross Ice Sheet thickening at the start of Stage 6. (iii) a period of carbonate deposition from 130 to 80 kA( Stage 5), more extensive than that at 175-190 kA. The expanding glacier (Taylor II) then advanced through the carbonates, and those of the earlier events, and redeposited. The events interpreted appear to correlate with global interglacials, as suggested by Hendy et al (1979). It seems that during interglacials, the East Antarctic Ice Sheet expands (the absence of a sea ice apron allows increased precipitation). As a result, expansion of the East Antarctic Ice Sheet would be expected as a consequence of greenhouse gas warming, offsetting sea level rises caused by melting of temperate glaciers and ice sheets.
Structure, light & temperature induced changes in the compound eyes of Antarctic crustaceans
(Thesis, The University of Waikato, 1980) Tiang, Kin Ming
The structure of the photoreceptors of three different Antarctic crustaceans was investigated by light and electron microscopy. Special attention was paid to light and temperature induced changes of the normal, i.e. dark-adapted eye. The apposition eye of Orchomene plebs shows structural modifications which are interpreted as adaptations to maximise photon capture in an environment of low ambient light intensities. Dark-light adaptational changes affect the position of the screening pigment granules, the volume of the random and the composition and density of the organelles in both retinula and interstitial cells. Exposure to a temperature of +10°c for seven hours affects the structural integrity of the rhabdoms and mimicks light-adaptation in animals that are kept in the dark. Rhabdoms regenerate as long as the animals are returned to water of 0°C. The ommatidia of the dorsal eye of Glyptonotus antarcticus possess very large diameters and are of the apposition type. Dark-light adaptational changes, which are confined to the dark eye if one eye is painted black and the other is left untouched, involve radial migration of screening pigment granules in the retinula cells surrounding the rhabdom. An elevation of the temperature also affects the position of the screening pigments, but the rhabdom ultrastructure is far less affected than that of Orchomene plebs. The compound eyes of the Ross Ice Shelf amphipod Orchomene grandis show the highest degree of structural adaptation to a dimly-lit environment. Following exposure to sunlight or darkness for one week at a temperature of approximately +1°C. the extraordinarily massive rhabdoms exhibit almost total disintegration. The density of screening pigment granules is so low that migrations upon dark-light adaptation are insignificant. The eye of Orchornene grandis shows the smallest capacity of all three species studied to adapt to different ambient light levels.
Microbial abundance and diversity surrounding mummified seals in Miers Valley, Antarctica
(Thesis, The University of Waikato, 2004) Robson, Lisa Marie
The presence of a number of mummified seal carcasses have been reported in the Dry Valleys of Antarctica. The location of seal carcasses were observed up to 240km in-land, and approximately 1500m above sea level. The extremely cold and dry conditions in the Dry Valleys act to mummify the seal remams, preserving these anomalies for an undetermined length of time. Given the virtual absence of above ground plant biomass in the Dry Valleys, the primary source of soil organic matter sustaining microbial ecosystems was not obvious. It was hypothesised that these large sources of organic contamination, in the form of a seal carcass, may act to enrich the localised environment surrounding the carcasses with carbon and nitrogen. The increased levels of organic carbon and nitrogen would result in increased microbial abundance and diversity. A total of 100 environmental samples were taken by Professors S.C. Cary, and D.A. Cowan, surrounding, and directly beneath eleven mummified seals located in Miers Valley, the Antarctic Dry Valleys, on Event D023 Terrestrial Microbiology Antarctic New Zealand 2001/2002. Three of these seals (MVSl, MVS3 and MVS 13) and the areas surrounding, were sampled extensively, and were the basis of research in this Master of Science thesis. Microbial diversity was investigated using molecular cloning and sequence analysis, and Denaturing Gradient Gel Electrophoresis, of 16S and 18S rDNA amplicons. A large diversity in bacterial populations present in the environmental samples taken from directly beneath the Miers Valley seal carcasses was observed in comparison to control samples of Miers Valley soils. The levels of microbial abundance were determined by luciferase-dependent luminometric ATP analysis, and analysis of the total quantities of double stranded DNA extracted from the environmental samples. Microbial abundance was found to be increased in samples taken in closer proximity to a seal carcass. Carbon and nitrogen analysis were conducted on all samples, using a fully automated Europa Scientific 20/20 isotope analyser. The level of carbon present in an environmental sample appeared not to influence the abundance of microorganisms. The levels of nitrogen measured were higher in environmental samples collected in close proximity to the seal carcasses. These samples displayed the greatest microbial abundance, and indicated large differences in the bacterial diversity compared to Miers Valley control samples. On the basis of these results, and ATP data, the hypothesis of this MSc thesis was determined to be correct. Microbial abundance was found to increase with enrichment of nitrogen surrounding MVS 1 and MVS 13 seal carcasses, and large differences in bacterial diversity were found in environmental samples showing the highest levels of nitrogen enrichment, compared to samples taken further away from the seal, or in Miers Valley control samples. This thesis effectively described the utilisation of cloning and sequence analysis, and denaturing gradient gel electrophoresis to investigate microbial diversity in Antarctic environmental samples. This study gave a greater understanding in microbial ecology in Miers Valley, Antarctica.
Volcanic geology and physical volcanology of Mount Morning, Antarctica
(Thesis, The University of Waikato, 2006) van Woerden, Timothy H.
Mount Morning is 70 km south of Ross Island and is part of the Cenozoic McMurdo Volcanic Group, which includes the presently active Erebus volcano. Few previous studies have investigated the mountain. The main exposures occur on two ridges on the northwest of the mountain, the field area is a roughly 3x5 km area on the northern part of the Riviera Ridge. The exposed geology indicates two main episodes of volcanic activity; Miocene trachytes and trachyandesites and Quaternary basanites and phonolites. This project is focused primarily on the Quaternary basanites and the objectives were: • Describe the physical volcanology. • Map and describe the surface geology and petrology and characterise the geochemistry of the rocks. • Develop models for the origin and evolution of the magmas represented by the rocks. • Characterise mantle xenoliths found in the area. The Quaternary eruptives are represented by eroded scoria cone remnants, dikes, and lava domes and flows. Breccia pipes mark eroded vent areas. Four scoria cones have been mapped and sampled in detail and these are interpreted to have formed by hawaiian and strombolian style activity. They contain distinctive agglutinate beds which have formed lava flows as lapilli and spatter horizons have accumulated on the flanks of cones close to source. The dominant rock-type is strongly porphyritic olivine and clinopyroxene basanite formed by crystal fractionation of olivine, clinopyroxene, opaque oxides, and minor amphibole, apatite and feldspar A dike within one of the scoria cones contains a spectacular suite of abundant, large xenoliths. Ultramafic mantle xenoliths include peridotite and pyroxenites, crustal xenoliths are granulite and granite. The presence of these xenoliths indicates that some basanites are very primitive.
Use of Time Domain Reflectometry (TDR) to determine moisture and temperature regimes in Antarctic soils
(Thesis, The University of Waikato, 2004) Wall, Aaron M.
Antarctic soil moisture and temperature data are important as the soil climate influence. Antarctic ecosystems, and the data may provide information on climate change, and the effects of human activities on the Antarctic environment. The objectives of this study were to: (1) determine the limitations of Hydra (TDR) soil moisture probes (Stevens Water Monitoring Systems Inc., Oregon, U.S.A.) for use in Antarctic conditions and in hydrocarbon-contaminated soils; (2) describe the soil moisture and temperature regimes of soils located at Scott Base, Marble Point and in the Wright Valley using existing TDR data; and (3) investigate the temperature and moisture regimes at hydrocarbon-contaminated sites at Scott Base and Marble Point. Determination of the limitations of Hydra (TDR) probes in Antarctic conditions was undertaken in the laboratory where experiments were undertaken to measure the effects of soil temperature, texture, salinity and hydrocarbons on TDR probe accuracy. Field investigations measured soil moisture content with the Hydra (TDR) probes and compared the results to gravimetrically determined soil moisture contents. Soil moisture and temperature data collected by soil climate stations at Scott Base, Marble Point and in the Wright Valley between 1999/2000 and 2001/02 summers, and in hydrocarbon-contaminated soils at Scott Base and Marble Point for the 1999/2000 and 2000/01 summers, were investigated. The laboratory experimentation showed that soil temperature, texture, and salinity all influenced the soil moisture results recorded by the Hydra (TDR) probes. Hydrocarbons did not influence the soil moisture content recorded by the Hydra (TDR) probes. The cumulative and offsetting effects of soil texture, temperature and salinity were considered to be within the ±3% limit of accuracy of the Hydra (TDR) probe stated by the manufacturers. Diurnal freeze-thaw cycles occurred throughout the summer at the 2-5 cm depth, and averaged 50 freeze-thaw cycles per summer at Scott Base, 79 in the Wright Valley, and 52 at Marble Point. At the 2 cm depth, the soil temperature was cumulatively >0°C for an average of 830 hours each summer at Scott Base, 1 680 hours in the Wright Valley, and I 110 hours at Marble Point. Up to five soil-moistening events were identified each summer at Scott Base and Marble Point, while soil-moistening was detected once by one sensor over three summers in the Wright Valley. During the soil-moistening events, volumetric liquid soil moisture contents increased up to 23% at Scott Base, 32% at Marble Point, and 6% in the Wright Valley. At the 2 cm depth, the liquid soil moisture was cumulatively >5% for an average of 860 hours each summer at Scott Base, 1 hour in the Wright Valley, and 310 hours at Marble Point. The drying period following soil-moistening for surface soils (2-5 cm depth) was about 6 days, which was extended to about 12 days when freeze-thaw cycles were occurring. Soil moisture regimes of the hydrocarbon-contaminated soils were similar to those of the uncontaminated soils. Lack of replication, TDR ϴᵥ accuracy, and spatial variability were limitations to the accurate comparison of hydrocarbon-contaminated soil data with that from neighbouring uncontaminated sites.
A study on molecular systematics of the Antarctic Bryum species and the development of microsatellite DNA markers in Bryum argenteum Hedw.
(Thesis, The University of Waikato, 2000) Hunger, Sarah A.
The "silver" species Bryum subrotundifolium Jaeg. (Bryaceae) in Antarctica has undergone numerous taxonomic revisions. This research used the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA (nrDNA) to estimate the phylogenetic relationships of silver Bryum specimens from Antarctica, the Subantarctic islands, New Zealand and Australia. Bryum subrotundifolium B. argenteum Hedw., B. capillare Hedw., and the non-silver species, B. pseudotriquetrum (Hedw.) Gaertn, Meyer et Scherb., which is also taxonomically difficult in Antarctica, were analysed with B. pseudotriquetrum used as an outgroup. Antarctic B. subrotundifolium formed a clade with the other B. subrotundfolium specimens and the B. argenteum specimens. This suggests that B. subrotundifolium is conspecific with B. argenteum. The Antarctic specimens formed a clade within the main B. argenteum!B. subrotundifolium clade. This combined with the variation in morphology observed in the Antarctic specimens suggest that the antarctic material is an ecotypical variant of B. argenteum. ITS sequence data indicated genetic homogeneity between geographically isolated populations of antarctic B. subrotundifolium contrary to evidence detected by random amplified polymorphic DNA analyses (RAPDs). Contamination was observed in the Antarctic moss specimens and multiple bands were detected in polymerase chain reaction (PCR) products from these specimens. The contaminating bands were found to be from a fungal species from the genus Phoma using a combination of molecular data and morphological examination. This provides a possible explanation for the high levels of variation detected using RAPDs and indicates the usefulness of universal DNA sequences with length polymorphisms, such as ITS sequences, for detecting contaminants in DNA samples for RAPD analysis. The development of microsatellite DNA markers in B. argenteum has commenced. This PCR-based technique is much less sensitive to contamination than RAPDs which use arbitrary primers to randomly amplify DNA throughout the genome. The primers used to amplify microsatellite DNA are targeted to a specific species and close relatives of it. Microsatellite DNA markers are expensive and time-consuming to develop. However, once developed they are far more reliable than RAPDs, require minimal amounts of DNA, are simple to use and can be used to detect variation at different levels within a population depending on the amount of polymorphism present in a locus. These markers will be employed in future population-level research of these cosmopolitan moss species in Antarctica and temperate regions.
The fate and effects of JP-5 fuel in Antarctic soil: A controlled experiment at Scott Base, Antarctica
(Thesis, The University of Waikato, 2002) Holmes, David J.
Hydrocarbon contamination of Antarctic soils is evident in limited areas where accidental fuel spills have occurred, usually near scientific bases or field camps. To understand the short-term fate and effects of fuel spills on Antarctic soils a contained experiment was established at Scott Base, Antarctica. Soil cores (105 x 10.5 cm diameter and 30 cm high) were filled with a sieved fraction(< 6.7 mm) of soil (Typic Anhyorthel), buried to the ground surface, and left to equilibrate over winter. Fuel (60 mL of JP-5, an equivalent depth of 7 mm) was applied in droplets, evenly to each of 63 cores. The remaining 42 cores were kept as controls. Ten cores (five control and five JP-5 treated) were weighed daily to monitor changes in moisture and snowfall, and to quantify the volatile loss of JP-5 fuel. In-situ temperatures (2, 5 and 20 cm depth) of both control and JP-5 treated cores were measured in triplicate at hourly intervals. Cores were destructively sampled in triplicate 0.1, 1, 3, 7, 14, 21, 28, 35, 42, 358, 365, 372, 379, and 397 days after fuel application and samples were returned, frozen, to New Zealand for total petroleum hydrocarbon (TPH) and microbial analyses. During destructive core sampling fuel penetration was observed to have reached a mean maximum depth of 15 cm ten days after JP-5 application, and 17 cm after one year. A large proportion (between 35% and 60%) of the fuel applied was lost to volatilisation within six weeks following the spill. The volatile loss of JP-5 fuel, as determined by weighing cores after correcting for moisture addition and evaporation of snowfall was about 9% after 18 hours, 26% after one week, and 35% after six weeks. The TPH content of the soil decreased in the 0-2.5 cm depth range from 46 000 mg kg- 1, two hours after fuel application, to 9 000 mg kg-1 after six weeks. In the depth range from 2.5 cm to the mean maximum depth of fuel penetration the TPH content of the soil decreased from 45 000 mg kg-1 two hours after fuel application to 10 000 mg kg-1 after six weeks. The corresponding volatile loss of JP-5 fuel, as determined from TPH concentrations within the total depth of fuel contaminated soil was about 50% after one week, and 60% after six weeks. Differences in the exact total fuel loss as recorded by weighing cores and TPH were attributed to various errors within each technique. The application of fuel had no measurable effect on soil temperature at 2 cm, 5 cm, and 20 cm depth, even though the surfaces of JP-5 treated cores were visibly darker than the control cores. The colour difference however had decreased markedly after three weeks. No differences were observed in the mean numbers of culturable heterotrophic bacteria and hydrocarbon-degrading microbes between JP-5 treated and control cores six weeks after the spill. It is, therefore, inferred that the initial application of fuel was non-toxic to culturable heterotrophic bacteria and hydrocarbondegrading microbes. Soil surface albedo measurements were also made over three previously contaminated sites in the Ross Sea region, and were found to be lower where the surface remained darkened by hydrocarbons, compared to nearby controls.
Sedimentation in Antarctic proglacial lakes
(Thesis, The University of Waikato, 1989) Sadler, Anthony John
A variety of Antarctic lakes occur either as proglacial lakes to glaciers, or as detached lakes within an enclosed drainage system in the Dry Valleys of McMurdo Sound, Antarctica. Some of these are the evaporated remnants of much larger proglacial lakes that formed during the last glacial, when the Ross Ice Shelf thickened, grounding on the continental shelf, and advanced landward entering many of the Dry Valleys. These former proglacial lakes have been the source of datable material using U/Th methods on the products of evaporation (CaC0₃), and ¹⁴C on algal deposits associated with many lacustrine sediments. These methods provide dates for glacial advances and hence allow correlation with similar northern hemisphere events. Interpretation of both the data generated, and morphologic evidence for paleo-lacustrine environments, requires a knowledge of how these former lakes developed and the processes occurring within them. To this end a modem proglacial lake, Trough Lake in Pyramid Trough, was selected to study and provide a model for sedimentation in the former lakes as well as a guide for interpretation of former proglacial environments. Although Trough Lake is proglacial to an alpine glacier, not a large ice sheet, and it is much smaller than the former lakes, it makes a satisfactory surrogatte. The principle aim was to examine the sedimentary processes occurring within the lake and to use this information to construct a facies model for the interpretation of former pro glacial lacustrine environments. The transport of ice-rafted, formerly glacial material, across the lake ice and the changes that occur to it have been examined. The results indicate that aeolian processes, as well as extraction of the fine fraction through the lake ice, occur concentrating the coarse fraction in ice-cored domes at the distal end of the lake. The fine fraction if it migrates through the lake ice becomes part of the normal, predominantly silt, lacustrine sediments. However, the distance a sand particle can move through the ice is size dependent, the coarser the material the smaller the distance it can migrate downward. This sand/ice interaction manifests itself in bimodal lacustrine sediments becoming progressively coarser away from the glacier until a point is reached where all the sand fraction that can migrate through the ice, has done so, and beyond this, lacustrine sediments will be unimodal. Thus it is apparent, that grain size distribution analysis of proglacial lacustrine sediments, and their associated drift, can be very useful in determining the size and structure of former Antarctic proglacial lakes. The calving of icebergs from the glacier snout and their eventual replacement by lake ice provides a mechanism by which lake ice can move at a rate of about 18 m per year (at Trough Lake) away from the glacier. The formation of the characteristic ice-cored domes found on many pro glacial or former proglacial lakes in the Mcurdo Sound area was demonstrated in a laboratory experiment designed to model the Antarctic environment. These domes are important as they often cover and preserve underlying lacustrine silts and algae when left behind by falling lake levels through retreat of the associated glacier. In addition these deposits can be used to gauge the extent of former lakes as well as providing samples for ¹⁴C dating. Evidence of seasonal cracks within the lake was observed and a core of sediment deposited through such a crack was extracted. This suggests another method by which lacustrine silts may be preserved in a very dry and windy Antarctic environment The physics of sand/ice interactions was examined in some detail, and it was demonstrated that the feasibility of sand moving through ice was not size related as had been suggested by some workers, however the rate at which sand moves through ice is inversely proportional to grain size. This provides a non-structural mechanism by which sand can move through lake ice and accumulate within the normal lacustrine sediments. By measuring temperature and chemical variation through the water column and the light penetrating the lake ice a model for a reverse convection cell operating within the lake was devised, and this explains how such a deep lake can maintain a very homogeneous water temperature and chemistry. Finally with the accumulated information a model for present and past proglacial lacustrine sedimentation was developed and this was used as the basis for a proposed facies model for paleo-proglacial lacustrine environments.
Soils and hydrology of Seabee Hook, Cape Hallett, Antarctica
(Thesis, The University of Waikato, 2006) Hofstee, Erica H.
The soils and hydrology of Seabee Hook, Cape Hallett, Antarctica were investigated during the 2003-04 and 2004-05 summer periods. Seabee Hook is a low lying spit that has been built up by the deposition of material, from nearby cliffs, by strong tidal currents. Seabee Hook is also the location of a large Adelie penguin (Pygoscelis adeliae) colony and was the location of a USNNZ research base, occupied from 1957-73. A soil map is presented of the Seabee Hook area. A soil association was identified between penguin mounds and intermound areas. Penguins build nests of stones on elevated sites, which at Cape Hallett are relict beach ridges. The penguins have exaggerated the topography of the beach ridges, primarily by adding 3-10 cm size stones ("penguin-stones") and guano, to form penguin mounds. Soils on penguin mounds contain guano in the upper 50 cm of the gravelly and sandy profile, and the guano layer overlies sub-rounded beachdeposited gravel and sand. Soils between beach ridges contain a thin veneer ( <3cm) of guano overlying the same basaltic gravelly sand found in the lower parts of the mound soils. The soils formed on the mounds have been classified usingUSDA Soil Taxonomy as Typic Haplorthels, and the soils formed between mounds have been classified as Typic Haplorthels/Typic Aquorthels depending on their soil moisture contents. The soil of the penguin mounds was enriched in many elements including nitrogen, organic carbon, phosphorus, cadmium, zinc, copper and it had increased electrical conductivity in soil horizons influenced by penguin guano compared to guano free horizons, soils from intermound areas, and soils away from the penguin colony. Radiocarbon dates from five penguin bones buried at the bottom of soil profiles indicate that Seabee Hook has been colonized by penguins for at least1000 years. That the colonization of Seabee Hook may have been rapid is evidenced by the consistent thickness of "penguin stones" and guano on top of the beach ridges throughout the area. Groundwater was situated perched above the ice cement as a shallow (<1-30 cm thickness of groundwater) unconfined aquifer. Groundwater within the penguin colony was sourced from melting snow drifts and ground ice. The occurrence of groundwater within the penguin colony at Seabee Hook showed considerable spatial and temporal variations over the 2003-04 and 2004-05summers, with ice cement levels decreasing from November and groundwater beginning to accumulate in early-December. Groundwater velocity through the permeable gravel and sand (porosity 23-33%) was up to 7.8 m day⁻¹, with hydraulic conductivities of 5 x 10⁻⁴ m s⁻¹ to 5 x 10⁻⁹ m s⁻¹. Groundwater abundance varied on an annual basis depending on the amount of snowmelt occurring during summer. The 2003-04 summer had a higher water table within the penguin colony than the 2004-05 summer. During 2003-04, surface water commonly occurred as ephemeral and intermittent streams and ponds. During2004-05, water was mostly confined to groundwater within the penguin colony, where it occurred in topographic lows. Surface water was present in only a few ponds within the colony during 2004-05, and was more common in the high meltwater zones away from the penguin colony. The penguins and close proximity to the ocean have affected the groundwater chemistry, with groundwater in the penguin colony elevated in salt (14 times more sodium, 41 times more potassium), nitrogen (7 times more nitrate,416 times more ammonia), and phosphorus (33 time more total phosphorus)compared to groundwater sourced away from the penguin colony on Seabee Hookand also compared to other terrestrial waters in Antarctica.
Antarctic bacteria and enzyme temperature optima
(Thesis, The University of Waikato, 2003) Hawkins, Sarah Kate
The temperature optimum of enzyme activity, as recently described by Daniel et al. (2001), is thought to play a central role in the adaptation of an enzyme to its environmental temperature. The aim of this research was to exploit this recent development in. determining temperature/activity relationships by correlating the environmental temperature of Antarctic bacteria with the properties of their enzymes. To avoid the problems associated with the comparison of taxonomically distant bacteria, enzymes were sourced from a single genus, Bacillus. Psychrotolerant bacteria were isolated from soils sampled at several sites (Dry Valleys, Bratina Island and Cape Crozier) in the Ross Sea region, Antarctica. At each sampling location, continuous 24 h temperature profiling of the top 2 cm of soil showed exposure to a wide temperature range (up to 20°C difference between maximum and minimum temperature) over the day. Initial characterisation revealed that 26 out of the 52 isolates obtained were Gram positive rods. Random amplified polymorphic DNA (RAPD) analysis of extracted genomic DNA and denaturing gradient gel electrophoresis (DOGE) of the 16S rRNA genes were performed on this subgroup. Five groups of closely related bacteria were identified, along with several unique isolates. 16S rDNA sequencing of eight of these isolates identified them as most likely representing the Bacillus, Planococcus, Arthrobacter, Pseudomonas, Carnobacterium and Psychrobacter genera. Isolates PRl and MV2 (identified as species of Bacillus) were found to have an approximate optimum growth temperature of 27°C and >30°C, respectively. A survey of extracellular proteases, esterases/lipases, glucosidases and galactosidases was initially performed on thermophilic Antarctic bacteria previously isolated from geothermal soils from Mount Erebus, Ross Island. The final choice of an intracellular enzyme, dihydrofolate reductase (DHFR), for temperature characterisation was preferable due to its ubiquitous expression and to allow comparison of the results with thermal properties of DHFRs from other sources. An extrapolation of the temperature dependence of PRl DHFR activity back to zero time revealed a 'real' temperature optima of 44°C, where at higher temperatures in the profile, the enzyme showed a decrease in catalytic rate greater than could be accounted for by irreversible denaturation. A temperature optimum determination for thermophilic DHFR from B. stearothermophilus also displayed a clear peak of activity at 47°C at zero time. Data obtained for the psychrotolerant and thermophilic enzymes were insufficient to confirm the environmental significance of this intrinsic property. However, the idea that 'true' temperature optima reflects the environmental temperature was validated, being lower for the psychrotolerant enzyme compared to the thermophilic enzyme.
Development of microsatellite markers for Antarctic Bryum Hedw. species
(Thesis, The University of Waikato, 2002) Harfoot, Rhodri T.
The objective of this thesis was to isolate microsatellite markers using the Glenn (2001) method from the species Bryum argenteum so as to be able to study these markers in Antarctic populations of Bryum species. Microsatellite regions have been found to be highly polymorphic and neutral markers, and usually genus specific, thus making them ideal for population genetic studies. The populations to be studied in the future have a large distribution over the Southern Victoria Land area, ranging from the Dry Valleys to Granite Harbour and Ross Island. Mosses are the most abundant and widespread of the vascular plant groups within continental Antarctica. They inhabit locations that are some of the more extreme on earth and experience periods of desiccation and darkness that can last as long as four months. For these reasons the establishment of mosses in Antarctica is a subject that has attracted great debate. One hypothesis suggests that mosses first became established when the ice retreated from the land approximately 17000 years ago, at the end of the last glacial maximum. The alternative hypothesis is that mosses survived as relictual populations over this period and have recently increased their habitat range. The study of microsatellite length polymorphism in populations will allow these hypotheses to be tested. The genus Bryum Hedw. (Bryaceae) is a highly polymorphic, cosmopolitan genus that is abundant in Antarctica over a wide range of locations. It is found from the Sub-Antarctic zone (Sub-Antarctic islands) to the continental zone (Continental Antarctica and Southern and Eastern Antarctic Peninsula. Thus covering a wide range of habitats from warm and wet (e.g. the Sub-Antarctic islands) to cold and very dry (e.g. the McMurdo Dry Valleys). To study the population genetics of Antarctic Bryum species, development of microsatellite markers was necessary as it has been found that with less specific methods such as RAPD-PCR, the DNA used for the analyses had been contaminated by co-extracted DNA from fungi living on the mosses, thus confounding the results obtained. Microsatellites, once developed, are genus or family specific, thus there is little risk of amplifying a contaminant when using microsatellite markers. Abstract This project failed to isolate any microsatellite markers from Bryum argenteum, due to experimental difficulties that occurred at three major stages; ligation, transformation and hybridisation screening of the genomic library. Future research should be focussed on completion of microsatellite isolation for this genus and on evaluation of the population relationships among Antarctic localities.
Biotreatability studies of oil-contaminated soils from Antarctica
(Thesis, The University of Waikato, 2005) Jimenez, Maria-Luisa Gutierrez-Zamora
Human activity in Antarctica has resulted in accidental fuel spills on soils. These are broadly damaging to the Antarctic ecosystem, and expensive to clean up completely by physical removal, therefore, alternative remediation techniques, like bioremediation, are required. Hydrocarbon-degrading bacteria have been isolated from Antarctic soils, but few biotreatability studies have been described. On the basis that limiting factors to bioremediation can be manipulated to enhance biodegradation of contaminated soils, this thesis research project aimed to test these limiting factors to contribute to the development of bioremediation protocols for hydrocarbon-contaminated soils from the Ross Sea Region, Antarctica. Hydrocarbon-contaminated and control uncontaminated soils collected from Scott Base, Marble Point and Wright Valley were chemically analysed for total hydrocarbons and chemical properties, and analysed for total heterotrophic and hydrocarbon-degrading microbes. Both contaminated and uncontaminated control soils were screened for the alkane catabolic genes Pp alkB, Rh alkBJ, Rh alkB2 and Rh alkB194 by polymerase chain reaction (PCR) and sequenced to determine the soils' alkane-degrading genetic potential. Additionall, hydrocarbondegrading bacteria isolated from Scott Base soils were characterised morphologically and screened for alkB gene homologues. The degradative ability of microbes was assessed by ¹⁴C-hexadecane mineralisation in soil microcosms at 15°C in all untreated soils, water and nitrogen amended Scott Base soils, Scott Base contaminated soil diluted 1 : 1 with uncontaminated soil, and Bull Pass soil bioaugmented with strains Rhodococcus sp. 5/1 and SB0-1, a hydrocarbondegrading microbial isolate from this study. Molecular analysis of 16S rDNA of SB0-1 showed DNA sequence homology of 99% with Rhodococcus sp. 5/14. Changes in microbial populations in the most successful enhancement treatments were detected by denaturant gradient gel electrophoresis (DGGE). Hydrocarbon-degraders were found only in Marble Point and Scott Base soils (from 10³ to 10⁶ colonies per gram dry weight soil). The most abundant alk gene in the soils was Pp a/kB, followed (in deceasing order of abundance) by Rh a/kB 1, Rh alkB2 and Rh alkB194. This indicated the possible presence of Pseudomonas and Rhodoeoeuss species in these soils. High rates of mineralisation were detected in Marble Point, ea. 60% in 75 days, and low rates in Scott Base soil, ea. 4% in 75 days. Nitrogen overfertilisation and water adjustments decreased mineralisation, but addition of 2500 mg N/kg-H20-soil combined with 10% moisture enhanced mineralisation ea. 4 times in a recent and old spill site in Scott Base soil, indicating that nitrogen was a limiting factor. Dilution of this soil with uncontaminated soil resulted in enhanced mineralisation, 8 times that of unamended soil, reaching ea. 40% mineralisation. DGGE showed that the diluted soil was enriched in a Rhodoeoeeus species. Dilution of the soil, and consequently of the contaminant, was the most successful treatment for Scott Base soil. This indicated that contaminant concentration was a limiting factor in this soil. Bioaugmentation of Bull Pass soil was partially successful; mineralisation was enhanced after addition of inoculum, but reduction in total hydrocarbons was minimal and attributed to abiotic loss. Overall, limiting factors to bioremediation can be manipulated to enhance biodegradation by nutrient amendments, dilution of contaminant, and inoculation of hydrocarbon-degraders. The implementation of these treatments may aid in remediation of contaminated soils from the Ross Sea Region.
Genetic diversity and phylogeography of New Zealand and Antarctic arthropods
(Thesis, The University of Waikato, 2005) McGaughran, Angela
Historical climatic and geological changes and ecological factors ( e.g. population size, dispersal abilities) are conducive to shaping genetic differentiation among natural populations. This thesis examines these issues in a phylogeographic context by looking at patterns of genetic diversity and dispersal of arthropods in two geographic regions. In southern New Zealand and its outlying islands, regional genetic divergence was revealed using mtDNA (COi) analysis for populations of idoteid isopods. Divergence within Austridotea benhami was < 2.0%. However, divergence within A. lacustris reached up to 10% with four main groupings: 1) Chatham Islands; 2) Campbell Island; 3) Fiordland; and 4) east coast South Island and Stewart Island. Similarly, A. annectens showed two main groups (4.4% diverg~nt): 1) Chatham Islands; and 2) east coast South Island and Stewart Island. These patterns are likely to be the result of geographical isolation, with some populations showing divergence corresponding to the availability of habitat (e.g. the divergence of A. lacustris and A. annectens on Chatham Islands may relate to the availability of this habitat - 4 Mya). Additionally, divergence of A. lacustris on Campbell Island and Fiordland may indicate a rare founder event or environmental change that resulted in population isolation. Overall, genetic data and geological history indicated that rare dispersal / events (or range expansion and population extinction), particularly during the Pliocene, may have played an important role in shaping the present-day distribution and genetic structure of freshwater idoteid isopods throughout New Zealand and its outlying islands. In Antarctica, analysis of patterns of mtDNA (COI) diversity and the geographic distribution of haplotypes among populations of the springtail Gomphiocephalus hodgsoni and the mite Stereotydeus mollis also revealed (congruent) patterns of genetic sub-structuring. Furthermore, genetic discontinuities suggested limited dispersal opportunities and isolation-by-distance for these taxa. Haplotype diversity within Wright and Victoria Valleys (St. John's, Olympus and Asgard ranges) was found to be higher here than in other areas and the distribution of haplotypes across sites was very heterogeneous. G. hodgsoni and S. mollis populations harboured eight and 23 new mtDNA haplotypes, respectively and showed links to previously sampled populations across southern Victoria Land. Accordingly, it is possible that this region may represent a primary location of a refugial source population from which many extant populations in southern Victoria Land have expanded since the Pleistocene and Holocene. Collectively, these studies revealed limited current dispersal and high levels of regional genetic differentiation for three arthropod taxa from fragmented habitats in both New Zealand and Antarctica. It provided insight into the biogeographic processes underlying modem distribution patterns of these taxa and highlighted the utility of the phylogeographic approach in reconstructing biotic history to further / knowledge of the relationships that exist between population processes and patterns of species diversity. Additionally, genetic analyses such as those performed here provided a basis to re-evaluate populations from a biodiversity perspective. Specifically, the New Zealand study clarified specific and generic relationships for potential reassessment of conservation status, while the Antarctic study identified biodiversity hotspots and priorities for conservation strategies (e.g. specially protected areas).

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