The unusual environmental conditions within caves provided unique opportunities for developing an understanding of ecosystem processes. However, relatively few studies have been conducted on the ecology of New Zealand cave systems. The primary aim of this research was to investigate changes in aquatic invertebrate communities along a longitudinal gradient from the surface into caves and investigate the fundamental drivers of cave communities. This study was carried out in three streams (two in pasture catchments and one in a forested catchment) flowing into caves in the Waitomo region, North Island, New Zealand. In order to address these aims I carried out a longitudinal survey of 12 sites in each stream, an experimental manipulation of food, and an isotopic study of a single stream. The longitudinal survey of the three cave streams revealed light intensity as well as algal and CPOM biomass all decreased significantly from outside the caves into caves. In contrast, water temperature, dissolved oxygen, stream width, depth, and velocity did not vary significantly with distance into caves. Benthic aquatic macroinvertebrate communities within the caves were a depauperate subset of surface communities, appearing to be structured by gradients in resources and colonisation through drift. However, some invertebrate taxa (primarily predators) were rarely found within caves, further suggesting that resource gradients were structuring cave communities. Surprisingly, the densities of some collector-browsers (primarily mayflies) increased within cave streams relative to surface densities. This may be due to a decrease in competition and predation, flexible feeding strategies, and high drift propensity. However, the benthic densities of most taxa within the caves appeared to be related to drift densities. Although surface forest and pastoral stream communities differed in community composition and density 32 meters within the caves invertebrate community diversity and density became similar, although specific taxa within communities varied. This convergence was attributed to similar environmental gradients within the caves. The resource addition experiment (adding leaf packs) indicated that cave streams were resource limited; the addition of leaves produced communities of similar richness and density across the environmental gradient. The isotopic survey suggested cave stream invertebrate communities were reliant upon similar basal resources to surface streams. However, within the cave epilithon appeared to be increasingly important while filamentous algae were absent. Cave aquatic invertebrates were also found to support terrestrial predators (spiders, harvestmen, and glow-worms), presumably increasing the abundance and diversity of terrestrial cave communities. In conclusion, aquatic cave communities were reliant upon surface derived resources and consequently strongly linked to surface land-use and managerial practices.

Water is a valuable and crucial resource, the protection of which poses environmental, social and economic challenges. Fundamental to the sustainable use of water is effective management. In the Canterbury region of New Zealand, nitrate contamination has become a resource management issue due to changes in land use and intensification, which have placed pressure on the region’s groundwater and surface water systems. The purpose of this study was to assess and track nitrate concentrations on the Central Canterbury Plains with specific emphasis on a local point source of nitrate, the Ashburton Meat Processors plant. To make this assessment review of historical data was followed by the collection of 131 groundwater and 25 surface water samples to analyse the geochemical properties of the water and the stable isotopic composition of nitrate in the water. It was hypothesised that nitrate concentrations at a regional scale have increased since regular records began and that the stable isotopic composition of different nitrate sources are not discernable. Nitrate concentrations across the Canterbury region were found to have increased, prompting concerns about water quality. Concentrations are elevated above natural background levels across much of the Canterbury Plains and extreme concentrations are associated with local point sources of nitrate. Nitrate concentrations down gradient of the Ashburton Meat Processing plant are shown to have declined approximately 5% per year for the past ten years, which is in contrast to the rest of the region, where average concentrations have nearly doubled in 20 years. The reduction of contamination from the point source is most likely the result of the implementation of better wastewater management practices in the early 21st century. The δ18O and δ15N values of nitrate were found to be relatively homogenous over the Canterbury Plains. Therefore, it is suggested by this study that the dual-isotope approach alone, is not a viable tool for nitrate source identification in the region. The uniform nitrate stable isotopic composition in Canterbury could be attributed to a single, principle source of nitrate, such as clover, that overprints other isotopic compositions of nitrate source, or may also be the result of soil processes and the farming techniques used in the region. This research presents important findings for the future of identifying and managing nitrate sources in the Canterbury region. Better management practices are required for the diffuse source(s) of nitrate contributing to the widespread contamination. Critical thinking and the willingness of stakeholders to engage in the identifying, documenting and solving problems is necessary to ensure the effective management and sustainability of this precious resource.

A novel tracer method has used 15N to label Escherichia coli and track the transport of bacteria, a common contaminant, through karst aquifers. Use of this method could provide valuable insight into the movement of bacteria in aquifers, which would help improve remediation methods and strategies. A wild strain of E. coli was isolated from the Cane Run/Royal Spring basin in the Inner Bluegrass region of Kentucky. The strain was serotyped O-:H- and virulence testing showed the strain did not have virulence factors of E. coli commonly pathogenic to humans. Five karst microcosms were filled with sterilized water collected from Royal Spring in Georgetown, Kentucky. Each microcosm was inoculated with wild-type E. coli, enriched in 15N, and incubated at 14° C for 130 days. The microcosms were periodically sampled for the concentration and nitrogen isotope composition of E. coli over 130 days. The E. coli survived at concentrations within one log of the average initial value of 5.62×1010 for the duration of the study. Statistical modeling showed no significant difference in δ15N values from day 1 and day 130. This strain is therefore recommended for traces in the Cane Run/Royal Spring basin.

Currently, bacterial movement in karst aquifers is not well understood. Use of stable isotopes to label non-pathogenic Escherichia coli as a particulate groundwater tracer in karst systems has been examined in previous studies. Loss of the stable isotope signal is anticipated in traces greater than 500 m in length. Potential loss of 15N due to predation by protozoa was examined. Filter-sterilized water from Royal Spring in Georgetown, Kentucky, was inoculated with a mixture of either Tetrahymena pyriformis or Colpoda steinii and 15N-enriched E. coli and stored in the dark at 14°C. Samples were analyzed for their nitrogen isotope composition (as δ15N values), and for population counts of bacteria and protozoa in a time course experiment, on days zero and seven after inoculation. Protozoan populations increased in the presence of E. coli, while bacterial populations decreased. δ15N values increased in T. pyriformis fed enriched E. coli but did not show values as high as the bacteria themselves, indicating that attenuation via predation may be a concern in future groundwater traces.

The long-term fate of hydrocarbons in the Gulf of Mexico (GOMx) following the 2010 Deepwater Horizon oil spill has yet to be fully characterized. Elemental (% C and % N), stable isotopes (δ13Corganic), and polycyclic aromatic hydrocarbon (PAH) molecular signatures were investigated in shelf and slope sediments collected in October 2010 and 2011 to gain insight into processes affecting the distribution and fate of spilled Macondo oil. Particulate organic carbon (POC) ranged between 1.55 and 2.22 wt. % in 2010 and 0.55 and 2.06 % in 2011 while the corresponding δ13Corganic ranges were from -23.37 to -20.77 ‰ (vs. PDB) in 2010, and -22.68 to -20.75 ‰ (vs. PDB) in 2011. Ranges of total polycyclic aromatic hydrocarbon (TPAH) concentrations were from 72.57 to 7,543.53 ng/g in 2010 and 25.55 to 16,582.77 ng/g in 2011. The range of measured values represented significant deviations from previous background measurements. This provided the basis for concluding that the Macondo spill altered the “background” organic carbon and hydrocarbon signature, that Macondo oil has weathered and/or biodegraded in the year following the spill, and that a significant spatial trend of hydrocarbons extended from the Macondo well across the northern GOMx in October 2010 and 2011.

Beluga whales (Delphinapterus leucas) and narwhals (Monodon monoceros) are arctic specialists. Both species show philopatry to their summer grounds, though the reason for this site tenacity is not well understood. Aside from migration routes, little is known about other aspects of monodontid ecology, such as their mating and feeding ecology. An understanding of the feeding ecology of a species may provide some insights into their mating ecology, and vice versa. The purpose of this thesis is to relative testes mass and dietary biomarkers to gain insights in the mating and feeding ecology of both species, as well as possible links between the two. Relative testes and brain masses and body masses of odontocetes were collected from the literature and analysed for correlations between sexual size dimorphism (SSD), relative brain mass, and relative testes mass. Results indicate that odontocete species follow a pattern of increasing SSD with decreasing testes mass. An examination of reproductive tracts from belugas and narwhal collected across the Canadian arctic was performed to examine differences in beluga and narwhal mating systems. Belugas were found to have larger relative testes masses, and narwhal testes masses were correlated with tusk length, indicating that sperm competition may play a larger role in the beluga mating system than for narwhal, and narwhal tusks may be honest indicators of male fitness. Investigations of narwhal and beluga feeding ecology using dietary biomarkers were conducted. In the summer, belugas appear to be congregating and feeding in the estuary plume during the summer, as opposed to along ice floe edges in the spring. Spring diets are representative of diets consumed during the beluga mating season, and no sexual segregation in carbon isotopes or fatty acids was apparent. There was no evidence for sexual segregation in feeding habits outside the mating season, either. Conversely, narwhal showed some evidence of sexual segregation outside the mating season, and the sexes may be feeding in different food webs. Results suggest that belugas may have a more promiscuous mating system, while narwhals are more polygynous. Implications for conservation for both species are discussed.

Mercury (Hg) is a global pollutant, yet Hg biomagnification, the increase in Hg with trophic level, remains poorly characterized in many regions, especially at subtropical latitudes. The present study assessed subtropical reservoirs of eastern China, which provided an opportunity to quantify Hg biomagnification under highly altered conditions that included high atmospheric Hg deposition, use of reservoirs for fisheries, manipulation of food webs through stocking and high fishing pressure, and increasing eutrophication. Despite China’s Hg emission and deposition rates that are among the highest worldwide, low fish Hg concentrations and Hg biomagnification rates were found; this was explained by food web structure and fish species characteristics. Stocked species occupied lower trophic levels and had significantly lower Hg concentrations relative to wild fishes. Evidence of decreased Hg concentrations with eutrophication (as indicated by chlorophyll-a) was observed, suggesting algal biodilution and/or somatic growth dilution. Relative to temperate lakes, zooplankton density dilution may also be causing reduced Hg concentrations in subtropical biota. Hydrogeomorphic features, such as water retention time and percent crop cover, explained Hg bioaccumulation factors and Hg concentrations at the base of the food web. Eutrophication and hydrogeomorphic features also influenced the bioavailability of selenium, which can protect against the toxicity of Hg at adequate concentrations, and the concentration of eicosapentaenoic acid, a beneficial fatty acid, in the planktivorous Bighead Carp (Hypophthalmichthys nobilis). This may indicate that the risk of exposure to the neurotoxicant methylmercury relative to benefits of fish consumption may increase with eutrophication in some fish species. Overall, the findings of this study suggest food web structure, eutrophication, and hydrogeomorphic features together explain low Hg concentrations in anthropogenically modified subtropical reservoirs in eastern China. / Thesis (Ph.D, Biology) -- Queen's University, 2014-07-01 11:35:12.637

Surface mining of oil sands results in extensive land disturbance, earth movement and water usage. After mining, the disturbed landscapes must be reconstructed and reclaimed as natural landforms. There are numerous challenges associated with understanding the responses of these landforms over time, including a need to track and characterize water movement through closure landforms to understand the hydrological responses of these landforms over time. This study attempted to use natural stable isotopes of water (δD and δ18O) to identify and characterize source waters from various closure landforms at an oil sands mine site. The study area is Syncrude‟s Mildred Lake mine, an open pit oil sands mine located in northern Alberta. A variety of groundwater, surface water and soil samples from a variety of landforms (overburden dumps, composite and mature fine tailings areas, tailings sand structures and freshwater reservoirs) were collected in an attempt to fully represent the isotopic distribution of waters across the mine site. Laboratory analysis of δD and δ18O was done on all samples. The local meteoric water line first established by Hilderman (2011) was redeveloped with additional precipitation data and calculated to be δD=7.0(δ18O) -18.6‰. A natural evaporation line having a slope of 5.3 was calculated for the mine site with samples collected from three surface water ponds on the mine site. Five primary source waters were identified on the mine site: process affected water/tailings, rainfall, snow, interstitial shale water and Mildred Lake water. It was found that these sources of water generally have unique natural stable water isotope signatures. Process affected water at the site generally had an enriched signature compared to other mine waters. The enrichment was attributed to fractionation from the recycle water circuit and natural evaporation. The characterizations of these source waters were then used in several hydrogeological examples to demonstrate that natural stable water isotopes can be applied to water balance estimates and to identify water movement processes related to closure landforms.

<p>Sea turtles are long lived marine species that are currently endangered because their life history and population dynamics hinder them from withstanding modern anthropogenic threats. Worldwide, fisheries bycatch in on the major threats to the survival of sea turtles and that is also the case in the Eastern Pacific. To establish regional conservation priorities for the mitigation of bycatch, it is essential to first obtain a comprehensive picture of the regional sea turtle bycatch situation. This comprehensive analysis was lacking for the Eastern Pacific; therefore one component of this dissertation (the first chapter) is focused on delivering a regional bycatch analysis for the Eastern Pacific. A literature review was conducted to obtain numbers of turtles captured, frequencies, bycatch and mortality rates per species and country in trawl, longline, and gillnet fisheries, and to compile results of mitigation measures. Moreover, estimates for current annual capture rates in trawl fisheries were obtained and compared with population numbers. </p><p>This regional bycatch used all the information compiled and synthesized to give conservation priorities at the regional level. The review underlines the high bycatch rates in trawls for Costa Rica, Guatemala, and El Salvador and the detrimental impact that these captures could have specially for hawksbill Eretmochelys imbricata due to its reduced population numbers and for green turtle Chelonia mydas due to its highest mortality rate. It also emphasizes the continuous lack of use of TEDs as a bycatch mitigation measure. In longline fisheries, the review identifies the high bycatch rates in pelagic longline fisheries of Costa Rica, Ecuador, and Nicaragua in a global context but given that olive ridley Lepidochelys olivacea is the most common species captured in these countries, it highlights the capture of loggerhead Caretta caretta and leatherback Dermochelys coriacea off Peru and Chile due to their small population numbers. Bottom longlines have high mortality rates compared with pelagic longlines in the region and the review identifies a need for further research in this area due to the scarce information but high mortality rates. The review also noted that some mitigation measures for pelagic longlines like circle hooks and hooks with appendages could bring improvements in the mitigation of bycatch in longline fisheries in the region, there is still considerable work to be done in technology transfer, sea turtle handling, and estimates of post-release mortality rates. </p><p>For gillnet fisheries, the most important highlight is how little information exists for the region given the high rates of bycatch for sea turtles in this gear. However, the difficulties of studying bycatch in highly dynamic and artisanal fisheries are recognized as the major impediment for this situation. Nevertheless, the high bycatch rates in areas where sea turtles congregate in high numbers like in foraging grounds for loggerhead in Baja California, Mexico and for greens in Paracas and Sechura, Peru, calls for either gear modifications (which has not been that successful), change of gear, or areas closed for gillnets. </p><p>The second half of the dissertation is focused on foraging ecology of oceanic sea turtles in the Southeast Pacific Ocean. Sea turtles in the oceanic stage are the least known stage due to the difficulty of accessing these individuals. However, it is a very important stage in the life cycle and can be critical for the population dynamics of sea turtles as some population models have shown. Therefore, this dissertation is filling a gap in the life cycle of sea turtle populations in the Eastern Pacific. </p><p>To study foraging ecology, we used Stable Isotope Analysis (SIA) of turtle tissues as well as potential prey items from the oceanic realm. SIA is a great tool because it gives an integrated view, from days to weeks, of prey from a consumer tissue. SIA also can be used to link consumers to habitats when elements that have spatial trends are used. In chapter two, we investigate the foraging ecology of three species of sea turtles to compare trophic status and to observe if spatial patterns were shown in the SIA signatures of sea turtles. To our knowledge this is the first study employing SIA to research the ecology of three species of sea turtles from the same time and space. Our results show that spatial patterns in delta15N and delta13C were observed in sea turtle's tissues as correlations with latitude. We also found that loggerhead's signatures differed significantly from green and olive ridleys, especially in terms of delta15N. Loggerheads had higher values of delta15N and also a wider nitrogen trophic niche. Greens and olive ridleys were similar in isotopic nitrogen values but they were significantly different in carbon. When analyzing a smaller group of animals captured in a more restricted area, nitrogen differences were not found which suggests that latitudinal spatial patterns play an important role in the nitrogen signature. On the contrary, carbon signatures still differed among turtles in the restricted area which suggest that the inshore-offshore trend is strong and made us conclude that loggerheads are restricted to oceanic areas but that greens and olive ridleys could be using both coastal and oceanic areas.</p><p>In chapter three, we conduct a mixing model analysis using the Bayesian program SIAR to identify the most important prey items for green, olive ridley, and loggerhead off Peru. Also, we wanted to identify the contribution of longline baits in the diet of oceanic turtles. The analysis was restricted to the central zone of our study area to avoid spatial trends in nitrogen. To use as sources in the model, we collected potential prey items offshore Peru during trips on longline fishing vessels and obtained their stable isotope signatures. Results from our mixing models show that for greens and olive ridleys, crustaceans, mollusks, and coastal Ulva (indicator of coastal prey) were the only important food items. In the case of greens, crustaceans had a very high proportional contribution and due to the fact that nitrogen values of crustaceans were the lowest ones among the sources it seems that greens would be eating in a lower trophic level. The importance of coastal Ulva for greens and olive ridleys is a confirmation of our findings from chapter two where we suggest that these two species could be using oceanic as well as coastal areas. </p><p>Results for loggerheads showed cnidarians, mollusks, mackerel and squid bait as foraging items and highlights the differences among this species and the other two. The lack of importance of coastal Ulva again suggests that loggerheads remain only in oceanic areas off Peru. Moreover, the importance of mackerel and squid, the most common longline baits, suggests this species is the one interacting the most with longline fisheries and that cumulative effect of multiple interactions could have a detrimental effect in this population.</p> / Dissertation

Although food quality is thought to play an important role in the survival of marine copepods, the extent of natural variability in food quality remains poorly characterized. Here I characterize the different scales at which food quality varies in copepods of the Strait of Georgia, British Columbia, Canada. Significant interannual variability occurs in the diet of Neocalanus plumchrus in the Strait of Georgia. Between 2001-06 the fatty acid profiles of N. plumchrus switched from omnivorous, oceanic signatures to herbivorous, diatom-dominated signatures. An index of food quality (DHA/EPA) is strongly correlated to the abundance of diapausing N. plumchrus, suggesting that the relative proportion of essential fatty acids provided by dinoflagellates and diatoms are related to the survival of this species. Combined fatty acid and stable isotope analysis indicated that the spring calanoid copepods of the Strait of Georgia occupy three trophic positions: Eucalanus bungii is herbivorous, Calanus marshallae and N. plumchrus are omnivorous, while Euchaeta elongata is carnivorous. Oceanic conspecifics of Strait of Georgia copepods experience a more omnivorous diet, as indicated by the presence of higher proportions of flagellate and carnivory markers, and lower proportions of diatom-based markers in their fatty acids. Despite spatial differences in the quality of their diets, the relative trophic positions of these copepods are constant as indicated by their stable isotope signatures. There is a correlation between the trophic information provided by stable isotopes and fatty acids. However, stable isotopes are not sensitive enough to capture the range of dietary variability observed in fatty acids, and fatty acids do not always provide reliable markers of carnivory and trophic position. Over the span of a season, copepods can utilize a wide range of dietary items including diatoms, flagellates, bacteria, detritus and microzooplankton. Copepods can switch from herbivory to carnivory in response to declining chlorophyll concentrations after the spring bloom, and are occasionally able to utilize detrital and bacterial sources. I conclude that the quality of copepod diets in the SoG varies on interannual, interspecific and seasonal scales. The implications of these findings are discussed in relation to ecosystem models of the area, and to copepod physiology.