123 research outputs found
The Karyotype of Blainville's Beaked Whale, Mesoplodon densirostris
No full textThe karyotype of the Odontocete whale, Mesoplodon densirostris, has not been previously reported. The chromosome number is determined to be 2n = 42, and the karyotype is presented using G-, C-, and nucleolar organizer region (NOR) banding. The findings include NOR regions on 2 chromosomes, regions of heterochromatic variation, a large block of heterochromatin on the X chromosome, and a relatively large Y chromosome. The karyotype is compared to published karyograms of 2 other species of Mesoplodon.No Full Tex
Adaption and application of cell-based bioassays to whole-water samples
No full textThe increasing presence of contaminants of emerging concern in wastewater and their potential environmental risks require improved monitoring and analysis methods. Direct toxicity assessment (DTA) using bioassays can complement chemical analysis of wastewater discharge, but traditional in vivo tests have ethical considerations and are expensive, low-throughput, and limited to apical endpoints (mortality, reproduction, development, and growth). In vitro bioassays offer an alternative approach that is cheaper, faster, and more ethical, and can provide higher sensitivity for some environmentally relevant endpoints. This study explores the potential benefits of using whole water samples of wastewater and environmental surface water instead of traditional solid phase extraction (SPE) methods for in vitro bioassays testing. Whole water samples produced a stronger response in most bioassays, likely due to the loss or alteration of contaminants during SPE sample extraction. In addition, there was no notable difference in results for most bioassays after freezing whole water samples, which allows for increased flexibility in testing timelines and cost savings. These findings highlight the potential advantages of using whole water samples in DTA and provide a framework for future research in this area.Full Tex
A comparative analysis of the karyotypes of three dolphins – Tursiops truncatus Montagu, 1821, Tursiops australis Charlton-Robb et al., 2011, and Grampus griseus Cuvier, 1812
No full textThe aim of this study is to produce G-banded karyotypes of three dolphin species, Tursiops truncatus Montagu, 1821, Tursiops australis Charlton-Robb et al., 2011, and Grampus griseus Cuvier, 1812, and to determine if any differences between the species can be observed. Monolayer skin cultures were established and processed for chromosome study by trypsin banding. The results indicate that the three species here investigated have the same diploid number (2n = 44) and very similar gross chromosome morphology, however G-banding allows distinction between each species. Chromosome 1 in G. griseus is significantly different from the other 2 species, and chromosome 2 in T. australis is subtly different from the other 2 species. This result is of potential significance in taxonomic studies, and can provide an unequivocal answer in the assessment of suspected hybrids between these species
Optimisation of an automated high-throughput micronucleus (HiTMiN) assay to measure genotoxicity of environmental contaminants
No full textAnthropogenic contaminants can have a variety of adverse effects on exposed organisms, including genotoxicity in the form of DNA damage. One of the most commonly used methods to evaluate genotoxicity in exposed organisms is the micronucleus (MN) assay. It provides an efficient assessment of chromosomal impairment due to either chromosomal rupture or mis-segregation during mitosis. However, evaluating chromosomal damage in the MN assay through manual microscopy is a highly time-consuming and somewhat subjective process. High-throughput evaluation with automated image analysis could reduce subjectivity and increase accuracy and throughput. In this study, we optimised and streamlined the HiTMiN assay, adapting the MN assay to a miniaturised, 96-well plate format with reduced steps, and applied it to both primary cells from green turtle fibroblasts (GT12s-p) and a freshwater fish hepatoma cell line (PLHC-1). Image analysis using both commercial (Columbus) and freely available (CellProfiler) software automated the scoring of MN, with improved precision and drastically reduced time compared to manual scoring and other available protocols. The assay was validated through exposure to two inorganic (chromium and cobalt) and one organic (the herbicide metolachlor) compounds, which are genotoxicants of concern in the marine environment. All compounds tested induced MN formation below cytotoxic concentrations. The HiTMiN assay presented here greatly increases the suitability of the MN assay as a quick, affordable, sensitive and accurate assay to measure genotoxicity of environmental samples in different cell lines.No Full Tex
Global oxygen isoscapes for barnacle shells: Application for tracing movement in oceans
No full textIt is helpful to understand the movement of animals and objects to inform species conservation and broader environmental management (e.g. by identifying the origin of marine debris). Tagging techniques are limited to investigations of future movement (e.g. after a tag has been applied), with no ability to understand where an animal or object has come from prior to encounter. However, studies that apply chemical techniques are able to address questions about historical movement prior to encounter, particularly through the analysis of stable isotopes from the tissues of migrating animals, or from barnacle shells that attach to migrating hosts. Barnacle shell isotope analysis is a promising technique that could provide a new understanding of the ecology of migrating marine fauna, or additionally the origin of marine debris. Here we use global datasets to assess the applicability of barnacle shell isotope techniques for identifying the origin and travel pathways of animals and objects that carry hitchhiking barnacles. We present the first global isoscapes for barnacle shell calcite, using these to identify areas that are likely to offer the finest spatial resolution for this application. We further demonstrate how isoscapes can be applied to back-trace animal migrations using real-world migration case studies of sea turtles and whales. We demonstrate that coastal areas and mid-latitude oceanic regions are likely to offer the best spatial resolution, and that migration pathways are able to be identified from successive barnacle shell samples. We expect that this work will allow for more efficient and precise future applications of barnacle shell isotope analyses to trace the movement and origin of barnacle hosts through marine waters.No Full Tex
Pelagic and coastal green turtles (Chelonia mydas) experience differences in chemical exposure and effect
No full textGreen turtles foraging in coastal areas are exposed to land-based chemical pollutants that accumulate in the habitats to which they show high site fidelity. However, prior to coastal recruitment, they may be exposed to a different range of chemical threats. The recent development of species-specific in vitro bioassays for marine turtles allows for an effect-based assessment of toxicological endpoints. Blood was collected from green turtles of two life-stages, ‘recent recruits’ and ‘coastal residents’, in Hervey Bay and Moreton Bay. Organic contaminants were extracted from blood using the QuEChERS method, and cytotoxicity of the extracts measured in green turtle skin cells. Although not statistically significant, extracts from ‘coastal residents’ exhibited greater mean toxicity compared to ‘recent recruits’, possibly indicative of increased chemical accumulation from coastal habitat exposure. The bioassay results also indicated that turtles foraging in Hervey Bay are at greater risk of chemical exposure than those foraging in Moreton Bay.No Full Tex
Assessing the impact of chemical exposure on the health of endangered sea turtles through toxicokinetics and toxicodynamics
No full textThe green sea turtle, Chelonia mydas, spends a considerable part of its life in coastal waters foraging on seagrass and/or algae, which brings it close to anthropogenic pollutant sources. Elevated concentrations of chemical contaminants from urban, industrial and agricultural run-off accumulate in coastal environments. These pollutants have the potential to cause serious harm to C. mydas populations. However, exposure and toxicity data are challenging to obtain for free-ranging, protected wildlife species like C. mydas. Furthermore, a lack of quantitative tools linking long-term external contaminant exposure, the uptake and tissue distribution of chemicals (toxicokinetics), and the biological pathway perturbations related to adverse health outcomes (toxicodynamics) hamper efforts by scientists and policymakers to quantify the risk of pollutants adversely affecting C. mydas
health. Changes in C. mydas population abundance, in turn, may affect the marine seagrass ecosystems, which, by extension, could potentially also impact human health and animals that rely on seagrass habitats.
The present thesis provided the means to research the hypothesis that land-based contaminants adversely impact the health of Australia’s resident green turtle populations. The following chapters in this thesis investigate the validity of this hypothesis. Valuable experimental toxicokinetic and toxicodynamic data are collected and described in Chapters 2 and 3. Chapter 4 used data from Chapter 3 to develop tools to confirm the initial hypothesis. Overall, this thesis describes the development of tools to aid risk assessors and policymakers in setting safe chemical exposure levels for green sea populations.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
The combined and interactive effects of multiple stressors on Great Barrier Reef ecosystems
No full textCoastal ecosystems are under threat by an increasing number of natural and anthropogenic stressors. These stressors co-occur in countless combinations, raising questions in the scientific community about their combined and/or interactive effects on individuals, populations and ecosystems. Environmental management of multiple stressors is challenging, as the governance of stressors are still largely based on individual effects, despite growing evidence of interactive effects in coastal ecosystems. As a result, the field of multiple stressor research is rapidly expanding to better understand, predict and manage stressor interactions.
This thesis aims to address questions surrounding deteriorating water quality, as an indication of ecosystem health, of the Great Barrier Reef (GBR). Land-based runoff has been identified as the greatest contributor to poor water quality in inshore marine ecosystems, such as the GBR. The three main water quality pollutants common to the GBR include pesticides, excess nutrients and suspended sediments. These pollutants originate from coastal development and agricultural practices and are transported to receiving waters via flood plumes. Following high rainfall during the Queensland wet season, GBR ecosystems are simultaneously exposed to high concentrations of pesticides, nutrients and sediments. This thesis presents a collection of related chapters that assess the effects of these three water quality stressors on coastal ecosystems.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
Reproductive Toxicology of Sea Turtles
No full textMany sea turtle species are threatened or endangered because of human activities including habitat loss, bycatch, and pollution. Various studies from around the world have found that anthropogenic contaminants accumulate within sea turtle tissues. Sea turtles have high site fidelity to coastal habitats, which are often close to human development, and therefore, pollutant sources. However, limited research has been performed on the impacts of contaminants on sea turtle reproduction. These research gaps were addressed by conducting a quantitative literature review of reptile reproductive toxicology to inform sea turtle reproductive toxicology research (Chapter 2). Three research priorities for better understanding reproductive toxicology in sea turtles were identified. These included: assessing contaminant exposure and maternal transfer in nesting sea turtles of known foraging locations (Chapter 3), investigating impairment of sex hormone production and the prevalence of common endocrine disruptors in sea turtles at various foraging locations (Chapter 4), and exploring the potential for contaminants to influence the sex determination of sea turtle hatchlings (Chapter 5).
A chemical risk assessment of two loggerhead sea turtle (Caretta caretta) nesting beaches in eastern Australia revealed a direct link between nesting turtle foraging location and hatchling contaminant concentrations (Chapter 3). There were significant differences in contaminant exposure and maternal transfer between two nesting locations, and these differences were directly correlated with known turtle foraging locations. Particularly, nesting turtle foraging locations reflected many of the contaminant differences found. There were also correlations between maternal blood and egg contaminant concentrations for a number of trace elements. In addition, cytotoxicity in a sea turtle specific cell-based bioassay suggested that organic contaminant concentrations in the blood of turtles foraging in some locations may be high enough to cause cell damage in vitro. Overall, however, the risk of trace elements and organic contaminant exposure to hatchling health were considered low at both nesting beaches. Despite this, these data suggest that reducing contaminant exposure in foraging locations could translate to reductions in trace element concentrations in hatchling turtles.
Within the five green turtle foraging grounds investigated in Chapter 4, there was evidence of widespread exposure to ethinylestradiol (EE2) and nonylphenol (NP) in immature green turtles. EE2 and NP are known endocrine disruptors, and well-studied for their negative estrogenic effects on aquatic organisms. EE2 and NP have been found to alter sex determination and alter sex hormone production in reptiles including freshwater turtles. EE2 residues in immature green turtles were up to 10 times higher than persons taking EE2 medication. There is little research as to whether EE2 and NP can maternally transfer to offspring. Maternal transfer of these compounds may lead to feminization of offspring. This study demonstrated that EE2 and NP exposure was common across many foraging locations in Queensland, and that the effects of these compounds on reproductive endpoints need to be investigated further.
In Chapter 5, sixteen green turtle clutches that were part of a parallel study on the impacts of nest cooling on sex ratios were examined for their trace element and organic contaminant concentrations. The contaminants found were converted into three indices: the percent of hatchlings in a clutch with trace element concentrations over median (TEOM), the percent of hatchlings in a clutch with estrogenic trace element concentrations over median (EstroEOM), and a predicted 17β-estradiol equivalent activity (PEEQA) of estrogenic trace elements. Many of the clutches deviated from their predicted sex ratio based on temperature (hereby sex ratio deviation), with some clutches having 90% more females than expected. When excluding an outlier, sex ratio deviation had a significant positive relationship with cadmium, antimony, and EstroEOM. In addition, there were significant relationships between mean clutch concentrations of cobalt, lead, antimony, barium, PEEQA, TEOM, EstroEOM and sex ratio. While there were no specific contaminants found to definitively affect sex determination, overall contaminant trends suggested that contaminants may affect sea turtle hatchling sex determination.
This thesis contributes to the priorities of sea turtle reproductive toxicology research that were established in the literature review (Chapter 2). Overall, I found that that sea turtle foraging grounds can influence hatchling contaminant accumulation in nesting populations; immature turtles are exposed to endocrine disrupting compounds within their foraging grounds; and that the potential effects of contaminants on sea turtle hatchling sex determination should be the subject of future studies. These research outcomes support management and conservation of sea turtles, illustrating that reducing contaminant inputs at sea turtle foraging locations can help reduce the potential reproductive harm of anthropogenic activities, and therefore may reduce the risk hatchling feminization from contaminants.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
Unique Post-telemetry Recapture Enables Development of Multi-Element Isoscapes From Barnacle Shell for Retracing Host Movement
No full textMany ecological investigations rely on understanding the movement of animals through marine environments. Most available tracking techniques are invasive (e.g., tissue sampling) and require extensive effort and/or cost (e.g., capture-mark-recapture or satellite telemetry). The isotopic compositions of barnacle shells (delta C-13 and delta O-18) are known to record the ambient water temperature and salinity conditions in which they grew. Thus, isotopic analysis of "hitchhiking" barnacles on animals or objects has the potential to yield information about their movement between water bodies of varying isotopic properties. We present, for the first time, isotopic data for barnacle shell samples that grew on a satellite-tracked sea turtle host. The satellite telemetry record, together with documented barnacle growth rates, allowed for sequential samples from individual barnacle shells to be assigned a specific time and location for direct comparison of isotope values to environmental conditions. We developed models that allow barnacle shell delta C-13 and delta O-18 to be linked, with a high degree of predictability, to sea surface temperature (SST) and salinity (SSS). Our sea turtle case study demonstrated how these models can be used to create isoscapes, allowing hosts to be tracked in space and time at higher resolution than most attempts to use soft-tissue isotopes for a similar purpose, and at considerably lower cost than satellite telemetry. The conceptual advance presented here could be applied widely to understand the movement of any animal or object that carries hitchhiking barnacles
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