1,721,004 research outputs found
Differences in marine megafauna in vitro sensitivity highlights the need for species-specific chemical risk assessments
No full textSea turtles, dolphins and dugongs can be exposed to large mixtures of contaminants due to the proximity of foraging locations to anthropogenic inputs. Differences in accumulation and effect result in differences of chemical risk to these species. However, little is known about the effect of contaminants in marine wildlife. Cell-based, or in vitro, exposure experiments offer an ethical alternative to investigate the effect of contaminants in wildlife. Data from in vitro studies can then be placed in an environmental context, by using screening risk assessments, comparing effect data with accumulation data from the literature, to identify risk to populations of marine wildlife. Cytotoxicity of Cr6+, Cd2+, Hg2+, 4,4’-DDE, and PFNA were investigated in primary skin fibroblasts of green turtles, loggerhead turtles, hawksbill turtles, dugongs, Burrunan dolphins, and common bottlenose dolphins. The general order of toxicity for all species was Hg2+> Cr6+ > Cd2+> 4,4′-DDE > PFNA, and significant differences in cytotoxicity were found between species for Cr6+, Cd2+ and PFNA. For Cd2+, in particular, cells from turtle species were less sensitive than mammalian species, and dugong cells were by far the most sensitive. The results from the cytotoxicity assay were then used in combination with published data on tissue contaminant concentrations to calculate risk quotients for identifying populations of each species most at risk from these chemicals. Cr, Cd and Hg were identified as posing risk in all six species. Dugongs were particularly at risk from Cd accumulation and dolphin species were particularly at risk from Hg accumulation. These results demonstrate the importance of using species-specific effect and accumulation data for developing chemical risk assessments and can be used to inform managers of priority contaminants, species, or populations. Development of additional in vitro endpoints, and improving links between in vitro and in vivo effects, would further improve this approach to understanding chemical risk in marine megafauna.No Full Tex
Temporal changes in chemical contamination of green turtles (Chelonia mydas) foraging in a heavily industrialised seaport
No full textPort Curtis, a major shipping port, has undergone significant expansion in the last decade, with plans for further development into the future. These activities may result in an increase of contaminant concentrations, threatening local wildlife including sea turtles. This study used a species-specific in vitro bioassay to examine spatial and temporal differences in exposure to, and effects of, organic contaminants in green sea turtles foraging in Port Curtis. Blood was collected from 134 green sea turtles (Chelonia mydas) from five locations in the port over four years. Organic contaminants were extracted from blood, and the cytotoxicity of the extracts to primary green sea turtle cells was assessed. Results indicated spatially similar chemical contamination throughout Port Curtis, at levels significant to sea turtle health, and with signs that chemical contamination may be increasing over time. These results can provide valuable information on the health of green turtles as further development occurs.Full Tex
Systematic review of reptile reproductive toxicology to inform future research directions on endangered or threatened species, such as sea turtles
No full textThreatened or endangered reptiles, such as sea turtles, are generally understudied within the field of wildlife toxicology, with even fewer studies on how contaminants affect threatened species reproduction. This paper aimed to better inform threatened species conservation by systematically and quantitatively reviewing available research on the reproductive toxicology of all reptiles, threatened and non-threatened. This review found 178 studies that matched our search criteria. These papers were categorized into location conducted, taxa studied, species studied, effects found, and chemicals investigated. The most studied taxa were turtles (n = 87 studies, 49%), alligators/crocodiles (n = 54, 30%), and lizards (n = 37, 21%). Maternal transfer, sex steroid alterations, sex reversal, altered sexual development, developmental abnormalities, and egg contamination were the most common effects found across all reptile taxa, providing guidance for avenues of research into threatened species. Maternal transfer of contaminants was found across all taxa, and taking into account the foraging behavior of sea turtles, could help elucidate differences in maternal transfer seen at nesting beaches. Sex steroid alterations were a common effect found with contaminant exposure, indicating the potential to use sex steroids as biomarkers along with traditional biomarkers such as vitellogenin. Sex reversal through chemical exposure was commonly found among species that exhibit temperature dependent sex determination, indicating the potential for both environmental pollution and climate change to disrupt population dynamics of many reptile species, including sea turtles. Few studies used in vitro, DNA, or molecular methodologies, indicating the need for more research using high-throughput, non-invasive, and cost-effective tools for threatened species research. The prevalence of developmental abnormalities and altered sexual development and function indicates the need to further study how anthropogenic pollutants affect reproductive output in threatened reptiles.No Full Tex
Validation of an in vitro bioassay using C6/36 insect cells as a model for evaluating toxicity of aquatic contaminants to invertebrates
No full textAquatic invertebrates play an important role in ecosystem functioning and are commonly used for in vivo toxicity assessments of environmental contaminants. However, in vitro bioassays employing invertebrate cell lines remain underutilised, despite their potential to improve toxicity testing and reduce reliance on whole-organism assays. This study aimed to develop and validate a suite of in vitro bioassays using the Asian tiger mosquito (Aedes albopictus) larval cell line (C6/36) to assess the cytotoxicity, oxidative stress, and genotoxicity of 24 common environmental contaminants. Cytotoxic effects were observed in 71 % of tested chemicals, while 25 % induced oxidative stress, and 63 % showed measurable genotoxicity. A strong correlation (R² = 0.83) between in vitro cytotoxicity data and acute toxicity data previously reported for Daphnia spp. suggests that C6/36 cells may serve as a reliable surrogate for traditional in vivo invertebrate toxicity tests. These findings support the broader application of invertebrate cell lines for environmental risk assessment, offering a refined approach for evaluating the toxicological properties of aquatic contaminants, while potentially reducing reliance on animal testing.Full Tex
Development and application of species-specific cell-based bioassays to assess toxicity in green sea turtles
No full textDespite the detection of a wide range of contaminants in the blood of green turtle populations foraging in three locations of northern Queensland – Upstart Bay, Cleveland Bay and the Howick Group of Reefs, little is known about the effects of these contaminants on turtle health. Newly developed cell-based bioassays using green turtle primary cell cultures provide an ethical, reproducible, and high-throughput method for assessing the risk of chemical exposure sea turtles. In this project, the toxicity of six priority metals (Mn, Co, Mo, As, Sb, Cu) and blood extracts from foraging turtles were tested in two bioassays adapted to green turtle primary skin and liver cells. Cytotoxicity of metals and blood extracts was measured in primary skin fibroblast cells using a resazurin assay. Glutathione-S-transferase (GST) activity was measured in primary skin fibroblasts and primary liver epithelial cells following exposure to metals and blood extracts. Arsenic, molybdenum, cobalt and copper were found to be cytotoxic to green turtle skin cells. Only manganese, cobalt and copper were found to alter GST activity, predominantly in skin cells, indicating a higher sensitivity of green turtle skin cells compared to liver cells. Effect concentrations of metals in both bioassays were above concentrations found in turtle blood. Turtle blood extracts from the three foraging grounds showed differences in cytotoxicity and GST activity. In both assays, blood extracts of turtles from Upstart Bay were the most toxic, followed by those from Cleveland Bay, then the Howick Reefs, suggesting turtles from Upstart Bay and Cleveland Bay may be at risk from current concentrations of organic contaminants. This study demonstrates that species-specific cell-based bioassays can be used effectively to assess chemical risk in sea turtles and their foraging grounds, and could be applied to assess chemical risk in other marine wildlife.No Full Tex
Improving rehabilitation outcomes using metabolomics: Health, recovery and biomarkers of mortality in sick and injured green turtles (Chelonia mydas)
No full textSea turtles are listed in threatened categories at national and international levels. Hundreds of sick and injured turtles are admitted to rehabilitation clinics annually, where recovery and release are important aspects of their conservation and management. There is considerable interest in establishing biochemical markers to gauge the health of sea turtles, and as diagnostic tools to facilitate informed decision-making about overall care and specific treatment needs during rehabilitation. We applied untargeted metabolomics to monitor the health of 28 green turtles (Chelonia mydas) admitted to a rehabilitation clinic in eastern Australia between October 2018 and April 2019. Malnutrition and ketosis were identified as major physiological manifestations in sea turtles entering rehabilitation. Specifically, decreased branch-chain (leucine, isoleucine and valine) and aromatic amino acids (tyrosine, phenylalanine and tryptophan) were observed at admission, along with increases in the ketogenic metabolite 3-hydroxybutyric acid and metabolites associated with peroxisomal disorders (pipecolic acid and beta-alanine). Receiver Operating Characteristic (ROC) analysis comparing successfully rehabilitated animals with those that died identified a suite of metabolites that were predictive of mortality. Results suggest that, regardless the source of injury or illness, a major cause of sea turtle mortality during rehabilitation relates to severe malnutrition that ultimately manifests as sepsis-induced metabolic failure. This showcases the strength of metabolomics for monitoring sea turtle health and informing care and management during rehabilitation. More broadly, this serves as a compelling case-study highlighting that advanced molecular analytical techniques are well positioned to play an important role in various aspects of veterinary medicine and conservation science.Full Tex
Elucidating the performance of UV-based photochemical processes for the removal of trace organic contaminants: Degradation and toxicity evaluation
No full textIn this study, the performance of standalone ultraviolet (UV) photolysis and UV-based advanced oxidation processes (AOPs), namely, UV/hydrogen peroxide, UV/chlorine, UV/persulphate, and UV/permonosulphate, were investigated for the degradation of 31 trace organic contaminants (TrOCs). Under the tested conditions, standalone UV photolysis did not achieve effective removal of TrOCs. To improve the degradation efficiency of UV photolysis, four different oxidants were added individually to the test solution. The effect of these oxidants in the absence of UV irradiation was also explored and only chlorine showed promising degradation of some contaminants. During the chlorination of 31 investigated TrOCs, only six demonstrated greater than 50% degradation. The combined UV-based AOPs demonstrated much improved degradation (ranging from 65 to 100%) depending on TrOC-structure and oxidant concentration. The UV/hydrogen peroxide process showed similar degradation of TrOCs, irrespective of the functional groups (i.e., electron withdrawing groups, EWGs and electron donating groups, EDGs) present in their structures. Conversely, the UV/sulphate and UV/chlorine based processes achieved better degradation of the TrOCs with EDGs in their structures. TrOCs degradation improved up to 40% when oxidants concentrations were increased from 0.1 to 1 mM, and further increasing the concentration to 2 mM did not improve degradation. Toxicity evaluation using bioluminescence test (BLT assay) demonstrated that except for UV/hydrogen peroxide, all UV-based AOPs increased the toxicity of the treated effluent, indicating generation of toxic by-products. This study elucidates the performance of four different UV-based AOPs for the removal of commonly detected diverse TrOCs for the first time.Full Tex
Combining analytical and in vitro techniques for comprehensive assessments of chemical exposure and effect in green sea turtles (Chelonia mydas)
No full textSea turtle populations foraging in coastal areas adjacent to human activity can be exposed to numerous chemical contaminants for long periods of time. For trace elements, well-developed, sensitive and inexpensive analytical techniques remain the most effective method for assessing exposure in sea turtles. However, there are many thousands more organic contaminants present in sea turtles, often at low levels as complex mixtures. Recently developed species-specific in vitro bioassays provide an effective means to identify the presence, and effect of, organic chemicals in sea turtles. This study used a combination of chemical analysis and effects-based bioassays to provide complementary information on chemical exposure and effects for three green turtle foraging populations (Chelonia mydas) in southern Queensland, Australia. Blood was collected from foraging sub-adult green turtles captured in Moreton Bay, Hervey Bay, and Port Curtis. Twenty-six trace elements were measured in whole blood using ICP-MS. Organic contaminants in turtle blood were extracted via QuEChERS and applied to primary green turtle skin fibroblast cell in vitro assays for two toxicity endpoints; cytotoxicity and oxidative stress. The trace element analysis and bioassay results indicated site-specific differences between foraging populations. In particular, turtles from Moreton Bay, a heavily populated coastal embayment, had pronounced cytotoxicity and oxidative stress from organic blood extracts, and elevated concentrations of Cs, Ag, and Zn relative to the other sites. Incorporating traditional chemical analysis with novel effects-based methods can provide a comprehensive assessment of chemical risk in sea turtle populations, contributing to the conservation and management of these threatened species.No Full Tex
Field-scale monitoring of green sea turtles (Chelonia mydas): Influence of site characteristics and capture technique on the blood metabolome
No full textGiven their threatened status, there is considerable interest in establishing monitoring techniques that can be used to evaluate the health of sea turtles in the wild. The present study represents a methodological contribution towards field-scale metabolomic assessment of sea turtles, by exploring differences in blood biochemistry associated with site characteristics and capture technique. We compared the metabolome of blood from animals at three locations (two coastal and one reefal), collected from turtles that were either resting or active, and sampled across multiple seasons at one location. Our results show clear differences in the metabolome of turtles from the three locations, some of which are likely attributable to differences in diet or forage quality and others which may reflect differences in other factors (e.g., occurrence of land-based contaminants or other biotic and/or abiotic stressors) between coastal and reefal sites. Our analysis also revealed the influence of capture technique on metabolite profiles, with numerous markers of physical exertion in animals captured while active that were absent in turtles sampled while resting. We observed a modest potential for temporal differences in the metabolome, but controlling for sampling time did not change the overall conclusions of our study. This suggests that temporal differences in the metabolome warrant consideration when designing studies to evaluate the status of sea turtles in the wild, but that site characteristics and capture technique are bigger drivers. However, sample size for this comparison was relatively small and further investigation of seasonal differences in the metabolome are warranted. Research exploring each of these factors more closely will further contribute towards achieving robust metabolomics analysis of sea turtles across large spatial and temporal scales.No Full Tex
Combined impacts of photosystem II-inhibiting herbicides and light availability on seagrass and marine microalgae
No full textThe combined and interactive effects of multiple stressors threaten coastal ecosystems, yet most ecological risk assessments used to inform environmental management still treat stressors separately. For marine microalgae and seagrass—particularly those common to the Great Barrier Reef, Australia—key stressors include low light from increased turbidity and herbicide exposure that runs off agricultural land. Despite co-occurring in aquatic ecosystems, the effects of these stressors are often studied separately, meaning any combined or interactive effects are overlooked. Here, we aimed to develop a conceptual synthesis of the physiological responses of marine microalgae and seagrass when exposed to these key stressors. We reviewed marine microalgae and seagrass exposure studies to understand how herbicide and light stress is assessed and generated hypotheses for the combined effects. In particular, we predict that photo-physiological, biochemical and whole-organism responses of aquatic plants and algae will interact antagonistically, additively or synergistically depending on the level of light availability and the endpoint measured. We recommend that future multi-stressor exposure experiments study how specific physiological processes interact to impact the growth of important primary producers such as microalgae and seagrasses. This will enable management to accurately determine the ecological risk of multiple stressors to aquatic species and ecosystems.Full Tex
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