1,721,047 research outputs found
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
Editorial – Virtual special issue (VSI) green turtles as silent sentinels of pollution in the Great Barrier Reef – Rivers to Reef to Turtles project
No full textThis special issue of STOTEN is dedicated to presenting the results of the WWF-Australia “Rivers to Reef to Turtles” project, which focused on investigating pollutants in the environment, food and bodies of green turtles (Chelonia mydas) on the Great Barrier Reef (GBR). The project brought together organic and inorganic trace chemical analysis, bioanalytical tools and individual health monitoring to investigate potential causes of an unusual mortality event in 2012. Together, the ten studies in this special issue highlight the shortcomings of current chemical monitoring and impact assessment programmes, which are focused on a limited number of prioritised chemicals and fail to account for the incredible diversity of toxicants released by human activities. It is essential that future management efforts consider the impact of these contaminants on the GBR, already under threat from global warming and sediment and nutrient runoff. Understanding the impact that chemical contaminants have on turtles not only informs green turtle conservation but can also, as they are sensitive and long-lived bioindicators of environmental health, guide efforts to protect, conserve and restore marine ecosystems such as the GBR.No Full Tex
A systematic review of freshwater microplastics in water and sediments: Recommendations for harmonisation to enhance future study comparisons
No full textMicroplastics are contaminants of emerging concern that have been widely detected in aquatic environments over the past decades. While in recent years an increasing number of studies has been published on microplastics in freshwater, there have been questions regarding inconsistency of the results due to large variations in methods and analytical techniques used in the literature. In this study, we adopted a systematic quantitative literature review approach to critically analyse 183 publications reporting microplastics in freshwater ecosystems. We also analysed the current approaches used for sampling, processing and analysis of microplastics in water and sediment, and the findings related to forms, polymer types, colours and sizes. Microplastics are frequently detected in various freshwater ecosystems across six continents, including lakes, rivers, estuaries, and wetlands. The reported microplastic concentrations span eight orders of magnitude in freshwater (1.2 × 10−3 to 5.42 × 105 particles/m3) and six orders of magnitude in sediments (8.1 × 10−1 to 9.5 × 105 particles/kg). Various forms, polymer types, colours and sizes of microplastics have been reported in water and sediment However, the heterogeneity in filter sizes, sampling and sample processing methodologies, and units of reporting between different studies make it difficult to bring together all studies and produce a comprehensive picture of the current state of knowledge. The results also highlight a lack of standardised quality assurance and quality control (QA/QC) protocols, which further makes meaningful assessment of the current literature difficult. We recommend using a consistent language for reporting microplastic concentrations and forms as well as providing more detailed information about sizes and chemical composition of microplastics to facilitate comparisons between studies. In addition, a comprehensive QA/QC protocol needs to be implemented during MP monitoring, especially, negative (field and laboratory) and positive controls, to produce reliable results.Full Tex
Microplastics and other anthropogenic fibres in large apex shark species: Abundance, characteristics, and recommendations for future research
No full textMicroplastics and microfibres are found ubiquitously in global oceans as well as marine organisms from different trophic levels. However, little is known about the presence of microplastics and microfibres in marine megafauna, such as sharks. This study provided the first investigation of the presence of microplastics and other anthropogenic fibres (i.e., cellulose based fibres) in intestine and muscle samples of four large apex shark species in Australian coastal waters. Microplastics and other anthropogenic fibres were found in 82% of the analysed intestine samples. The mean abundance in intestine samples was 3.1 ± 2.6 particles/individual, which corresponded to 0.03 ± 0.02 particles/g of intestine, across all shark species. The size of particles ranged from 190 to 4860 μm in length with 92% being fibrous in shape and the rest fragments. FTIR spectroscopy identified that 70% of fibres were cellulose-based followed by polyethylene terephthalate (PET), while the fragments were polyethylene and polypropylene. In shark muscles, 60% of samples contained microplastics and other anthropogenic fibres, again with the majority being cellulose-based fibres followed by PET fibres. Methodological differences hinder a more comprehensive assessment of microplastic contamination across studies. Additionally, we identified some challenges which should be factored in for future studies looking at the presence of microplastics as well as other anthropogenic fibres in these large marine organisms. Overall, the findings provide first evidence of microplastics and other anthropogenic fibres not only in the intestines, but also in muscle tissues of large apex shark species.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
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
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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