Maternal transfer and sublethal immune system effects of brevetoxin exposure in nesting loggerhead sea turtles (Caretta caretta) from western Florida

Health risks associated with the consumption of sea turtles: A review of chelonitoxism incidents and the presumed responsible phycotoxins

Consuming the meat of some marine turtles can lead to a specific type of seafood poisoning known as chelonitoxism. A recent poisoning event (March 2024) on the Tanzanian island Pemba, resulting in the death of 9 people and hospitalization of 78 others, underscores the need to obtain an up to date overview and understanding of chelonitoxism. Here, we document a global overview of poisoning incidents resulting from the consumption of sea turtle flesh worldwide. All events combined involved over 2400 victims and 420 fatalities. Incidents were predominantly reported in remote regions (often islands) across the Indo-Pacific region. Reported health effects of consuming poisonous sea turtles include epigastric pain, diarrhea, vomiting, a burning mouth and throat sensation, and dehydration. In addition, ulcerative oeso-gastro-duodenal lesions, which occasionally have resulted in hospitalization and death, have been reported. Lyngbyatoxins have been suggested as (one of) the causative agents, originating from the cyanobacterium Moorena producens, growing epiphytically on the seagrass and seaweed consumed by green turtles. However, due to the limited evidence of their involvement, the actual etiology of chelonitoxism remains unresolved and other compounds may be responsible. The data outlined in this review offer valuable insights to both regulatory bodies and the general public regarding the potential risks linked to consuming sea turtles.

Emerging Insights into Brevetoxicosis in Sea Turtles

This review summarizes the current understanding of how brevetoxins, produced by Karenia brevis during harmful algal blooms, impact sea turtle health. Sea turtles may be exposed to brevetoxins through ingestion, inhalation, maternal transfer, and potentially absorption through the skin. Brevetoxins bind to voltage-gated sodium channels in the central nervous system, disrupting cellular function and inducing neurological symptoms in affected sea turtles. Moreover, the current evidence suggests a broader and longer-term impact on sea turtle health beyond what is seen during stranding events. Diagnosis relies on the detection of brevetoxins in tissues and plasma from stranded turtles. The current treatment of choice, intravenous lipid emulsion therapy, may rapidly reduce symptoms and brevetoxin concentrations, improving survival rates. Monitoring, prevention, and control strategies for harmful algal blooms are discussed. However, as the frequency and severity of blooms are expected to increase due to climate change and increased environmental pollution, continued research is needed to better understand the sublethal effects of brevetoxins on sea turtles and the impact on hatchlings, as well as the pharmacokinetic mechanisms underlying brevetoxicosis. Moreover, research into the optimization of treatments may help to protect endangered sea turtle populations in the face of this growing threat.

Individual and combined impact of microplastics and lead acetate on the freshwater shrimp (Caridina fossarum): Biochemical effects and physiological responses

Microplastics and heavy metals pollution is recognised as a major problem affecting aquatic ecosystems. For this reason, this study aims to assess the toxicity of different concentrations of polyethylene microplastics (PE-MPs) (0.0, 500, and 1000 μg L-1) with a mean size of 15-25 μm and lead acetate Pb(C2H3O2)2 (0.0, 2.5, and 5 mg L-1), both individually and in combination, through the exposure of the freshwater grass shrimp, Caridinia fossarum for 15 days, focusing on microplastic interaction with co-occurring contaminants. After being exposed to both contaminants, either individually or in combination, significant alterations in numerous biochemical markers were observed. Specifically, exposure to lead acetate alone resulted in significant changes across ALP, AST, ALT, LDH, GGT, and BChE enzyme activity levels indicating hepatotoxicity and neurotoxicity. Also, Pb exposure led to alterations in total antioxidant capacity, MDA, total lipids, and glycogen contents, signalling the onset of oxidative stress. Exposure to PE-MPs alone led to changes in ALP, LDH, GGT, and BChE enzyme levels, and in MDA, total lipids, and glycogen samples' contents. Remarkably, the study observed increased bioaccumulation of lead acetate in samples treated with the combination, emphasizing the synergistic impact of PE-MPs on the toxicity of lead acetate. This synergy was also evident in AST and ALT enzyme activity levels and MDA contents. This underscores the necessity for measures to address both microplastic pollution and heavy metal contamination, taking into account the synergistic behaviour of MPs in the presence of concurrent contaminants.

Single and combined effects of CuSO4 and polyethylene microplastics on biochemical endpoints and physiological impacts on the narrow-clawed crayfish Pontastacusleptodactylus

This study investigated the toxicity of polyethylene microplastics (MPs; <0.02 mm) and CuSO4, alone and in combination, on the freshwater crayfish Pontastacus leptodactylus. In this study, the crayfish were exposed to PE-MPs (0.0, 0.5, and 1 mg L-1) and CuSO4·5H2O (0.0, 0.5, and 1 mg L-1) for a period of 28 days. Next, multi-biomarkers, including biochemical, immunological, and oxidative stress indicators were analyzed. Results showed that co-exposure to PE-MPs and CuSO4 resulted in increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and decreased alkaline phosphatase (ALP), butyrylcholinesterase (BChE), and gamma-glutamyl-transferase (GGT). Triglycerides, cholesterol, glucose, and albumin content also increased. Although no significant change was observed in lysozyme and phenoloxidase activities in crayfish co-exposed to 0.5 mg L-1 MPs and 0.5 mg L-1 CuSO4, their activities were significantly decreased in other experimental groups. Oxidative stress parameters in hepatopancreas indicated increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and in malondialdehyde (MDA) levels, but decreased catalase (CAT), glucose 6-phosphate dehydrogenase (G6PDH), and cellular total antioxidant (TAC). Results showed that the sub-chronic toxicity of CuSO4 was confirmed. The study confirmed the toxicity of CuSO4 and found that higher concentrations led to more severe effects. Co-exposure to PE-MPs and CuSO4 primarily compromised the endpoints, showing increased toxicity when both pollutants were present in higher concentrations. The activities of POX, LYZ, ALP, GGT, LDH, and CAT were suppressed by both CuSO4 and MPs. However, a synergistic increase was observed in other measured biomarkers in crayfish co-exposed to CuSO4 and MPs.

Microplastics evidence in yolk and liver of loggerhead sea turtles (Caretta caretta), a pilot study

The potential toxicity of microplastics is a growing concern for the scientific community. The loggerhead sea turtle (Caretta caretta) is particularly inclined to accidently ingest plastic and microplastic due to its long-life cycle features. The possible transfer of microplastics from the female to the eggs should be investigated. The present study investigated the presence of microplastics in yolk and liver samples evaluating the number of melanomacrophages in the hepatic tissue as a possible biomarker of microplastics impact on the embryonic health status. The biometric parameters and liver histological analysis of 27 and 48 embryos (from two different nests respectively) at the 30 stage of development were analyzed. Raman Microspectroscopy was performed to identify the microplastics after alkaline digestion (10% KOH) of yolk and portion of liver from 5 embryos at the 30 developmental stage per nest. Microplastics were found in yolk and liver of loggerhead sea turtles at late embryonic stage for the first time. All microplastics were smaller than 5 μm and were made of polymers and colors suggesting their diverse origins. A total number of 21 microplastics, with dimensions lower than 5 μm, were found between the two nests (11 and 10 microplastics respectively). Only two shape categories were identified: spheres and fragments. The most frequent polymers observed were polyethylene, polyvinyl chloride and acrylonitrile butadiene styrene (31.5%, 21.1% and 15.8% respectively). Despite the eggs showing a higher number of microplastics in yolk samples than liver (15 and 6 microplastics in yolk and liver respectively), a positive correlation was observed only between the number of melanomacrophages (r = 0.863 p < 0.001) and microplastics in the liver. This result may suggest that microplastics could exert some effects on the hepatic tissues. Future studies should investigate this aspect and the possible relation between microplastics and other stress biomarkers.

Understanding contaminant exposure risks in nesting Loggerhead sea turtle populations

Queensland loggerhead turtle nest numbers at Mon Repos (MR) indicate population recovery that doesn't occur at Wreck Island (WI). Previous research illustrated that MR and WI turtles forage in different locations, potentially indicating risks differences. Blood, scute, and egg were collected from turtles nesting at MR and WI, with known foraging sites (from concurrent studies). Trace element and organic contaminants were assessed via acid digestion and in vitro cytotoxicity bioassays, respectively. WI turtles had significantly higher scute uranium and blood molybdenum compared to MR turtles, and arsenic was higher in WI turtles foraging north and MR turtles foraging south. Egg and blood titanium, manganese, cadmium, barium, lead, and molybdenum, and scute and egg selenium and mercury significantly correlated. Blood (75 %) extracts produced significant toxicity in vitro in turtle fibroblast cells. In conclusion, reducing chemical exposure at higher risk foraging sites would likely benefit sea turtles and their offspring.

Immunity in Sea Turtles: Review of a Host-Pathogen Arms Race Millions of Years in the Running

The immune system of sea turtles is not completely understood. Sea turtles (as reptiles) bridge a unique evolutionary gap, being ectothermic vertebrates like fish and amphibians and amniotes like birds and mammals. Turtles are ectotherms; thus, their immune system is influenced by environmental conditions like temperature and season. We aim to review the turtle immune system and note what studies have investigated sea turtles and the effect of the environment on the immune response. Turtles rely heavily on the nonspecific innate response rather than the specific adaptive response. Turtles' innate immune effectors include antimicrobial peptides, complement, and nonspecific leukocytes. The antiviral defense is understudied in terms of the diversity of pathogen receptors and interferon function. Turtles also mount adaptive responses to pathogens. Lymphoid structures responsible for lymphocyte activation and maturation are either missing in reptiles or function is affected by season. Turtles are a marker of health for their marine environment, and their immune system is commonly dysregulated because of disease or contaminants. Fibropapillomatosis (FP) is a tumorous disease that afflicts sea turtles and is thought to be caused by a virus and an environmental factor. We aim, by exploring the current understanding of the immune system in turtles, to aid the investigation of environmental factors that contribute to the pathogenesis of this disease and provide options for immunotherapy.

Dietary Arthrospira platensis in Rainbow Trout (Oncorhynchus mykiss): A Means to Reduce Threats Caused by CdCl2 Exposure?

The rainbow trout (Oncorhynchus mykiss) is one of the most commercially sought-after freshwater fish species and one of the most farmed in the world. On the other hand, aquaculture breeding frequently results in outbreaks of infectious diseases and pests, and compromises the production and welfare of fish. Arthrospira platensis (known as "Spirulina") has been used as a supplement in diets to enhance fish welfare in recent years because of its beneficial properties. This study aimed to assess the possible protective effects of Arthrospira platensis on rainbow trout specimens exposed to three different doses of the toxicant CdCl₂. The experiment was carried out using five experimental treatments of 40 individuals each: control group; group II (0.2 mg CdCl₂ per kg of commercial fish feed); group III (0.2 mg Kg^-1 of CdCl₂ plus 2.5 g per kg of A. platensis); group IV (0.2 mg Kg^-1 of CdCl₂ plus 5 g per kg of A. platensis); group V (0.2 mg Kg^-1 of CdCl₂ plus 10 g per kg of A. platensis). During the experiment, dietary supplementation of A. platensis normalized all serum and blood parameters altered by the presence of CdCl₂. A. platensis also had a protective effect on markers of oxidative stress.

Putative high-level toxicity pathways based on evidence of brevetoxin immunotoxicity in marine fauna

Red tide events, caused by a toxin producing dinoflagellate, Karenia brevis, occur annually in Florida and Texas. These events lead to health risks for both humans and wildlife that utilize coastal environments. Brevetoxins, potent lipophilic neurotoxins produced by K. brevis, modulate immune responses in laboratory studies with model organisms and in the natural environment in both humans and wildlife. Studies show that brevetoxins activate immune cells, stimulate production of gamma-globulins, cytokines, and neutrophils, modulate lysozyme activity, induce apoptosis, and modulate lymphocyte proliferation in marine species. The objective of this review was to summarize brevetoxin-induced immunotoxicity in marine animals based on available peer-reviewed literature about K. brevis blooms and associated health concerns and propose putative toxicity pathways. This review identifies knowledge gaps within current brevetoxin induced immunotoxicity research, including assessing the long-term impacts of brevetoxin exposure, elucidating the mechanistic linkages between brevetoxins and immune cells, and evaluating repeated and chronic versus acute brevetoxin exposure implications on overall organismal health. The putative immunotoxicity pathways based on evidence from brevetoxin-exposure in marine fauna described in this review represent a useful tool and resource for researchers, wildlife managers, and policy makers. This review and proposed putative immunotoxicity pathways will inform decisions regarding the risks of algal blooms, as it pertains to marine animal health.

Toxic effects of polyethylene microplastics on transcriptional changes, biochemical response, and oxidative stress in common carp (Cyprinus carpio)

Aquatic ecosystems have become a place for accumulating microplastics (MPs). MPs can directly or indirectly damage organisms. Although studies of the toxicity of MPs, there are insufficient literature reports on the effects of MPs on freshwater aquatic life. Therefore, this study aimed to evaluate the effect of MPs toxicity on Cyprinus carpio. In this study, biochemical parameters, oxidative biomarkers, and gene expression were assayed in fish exposed to 0, 175, 350, 700, and 1400 μg L^-1 of MPs for 30 days. MPs were detected in the liver and intestine of fish using FTIR-analysis. Mt1, Ces2, and P450 mRNA expression were enhanced in the hepatocytes of fish exposed to MPs, while Mt2 gene expression was significantly decreased. After exposure to MPs, MDA and carbonyl protein levels were higher than those of the reference group. The antioxidant capacity and glycogen contents in the hepatocytes significantly declined. MPs significantly inhibited glutathione reductase (GR), glucose 6-phosphate dehydrogenase (G6PDH), and catalase (CAT) activities. However, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities increased. MPs decreased the total protein, globulin levels, and butyrylcholinesterase (BChE) activity in blood. In contrast, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and creatine phosphokinase (CPK) activities increased in treated-fish with MPs. Glucose, creatinine, cholesterol and triglyceride concentrations in fish exposed to MPs were significantly higher than that of the reference group. Consequently, MPs exposure could disrupt biochemical homeostasis, oxidative stress and alter the expression of genes involved in detoxification.

The influence of Lake Okeechobee discharges on Karenia brevis blooms and the effects on wildlife along the central west coast of Florida

Blooms of the dinoflagellate Karenia brevis (K. brevis) are a common occurrence in the Gulf of Mexico, especially along Florida's coast. The blooms produce brevetoxins, potent neurotoxins that are associated with mortalities of marine wildlife. In recent years, K. brevis blooms seem to have become more frequent and intense. The cause of these suspected increases is highly debated, with one suggested explanation being anthropogenic eutrophication. Patient records from the Clinic for the Rehabilitation of Wildlife (CROW) on Sanibel Island, Florida, USA, and K. brevis cell count samples from the west coast of Florida were used to assess trends in red tides and affected wildlife. Flow data from the Okeechobee waterway was used to investigate if discharges from Lake Okeechobee and the Caloosahatchee Estuary, where eutrophication is present, influence red tides along Florida's central west coast. Overall, K. brevis blooms show trends of increasing intensity and duration along Florida's coast between 1954 and 2020 (latest data available). This means the amount of wildlife affected will likely increase in the future, as a linear relationship was found between the number of admissions to CROW and K. brevis densities. Furthermore, water discharges from the Okeechobee waterway (including Lake Okeechobee and the Caloosahatchee Estuary) into the Gulf of Mexico were significantly correlated with K. brevis densities, which suggests that anthropogenic pollution might play a role in the observed increases. Clear correlations were found between K. brevis densities and brevetoxicosis patient numbers admitted, and this was strongest with overall admissions lagging 23 days behind cell counts. This further confirms brevetoxins as the likely cause of their morbidity and supports previous research on brevetoxin retention in the environment. Different species groups had significant correlations with K. brevis cell counts, double-crested cormorants showing the strongest link, and there were significant differences between these groups in lag times. The differences are likely due to their distinct foraging behaviours or susceptibilities to brevetoxins. These findings can help predict future trends in red tides and can guide further research on the effects of discharges on K. brevis blooms.

Use of intravenous lipid emulsion therapy as a novel treatment for brevetoxicosis in sea turtles

The southwest coast of Florida experiences annual red tides, a type of harmful algal bloom that results from high concentrations of Karenia brevis. These dinoflagellates release lipophilic neurotoxins, known as brevetoxins, that bind to sodium channels and inhibit their inactivation, resulting in a variety of symptoms that can lead to mass sea turtle strandings. Traditional therapies for brevetoxicosis include standard and supportive care (SSC) and/or dehydration therapy; however, these treatments are slow-acting and often ineffective. Because red tide events occur annually in Florida, our objective was to test intravenous lipid emulsion (ILE) as a rapid treatment for brevetoxicosis in sea turtles and examine potential impacts on toxin clearance rates, symptom reduction, rehabilitation time, and survival rates. Sea turtles exhibiting neurological symptoms related to brevetoxicosis were brought to rehabilitation from 2018-2019. Upon admission, blood samples were collected, followed by immediate administration of 25 mg ILE/kg body mass (Intralipid® 20%) at 1 mL/min using infusion pumps. Blood samples were collected at numerous intervals post-ILE delivery and analyzed for brevetoxins using enzyme-linked immunosorbent assays. In total, nine (four subadults, one adult female, four adult males) loggerheads (Caretta caretta), five (four juvenile, one adult female) Kemp's ridleys (Lepidochelys kempii), and four juvenile green turtles (Chelonia mydas) were included in this study. We found that plasma brevetoxins declined faster compared to turtles that received only SSC. Additionally, survival rate of these patients was 94% (17/18), which is significantly higher than previous studies that used SSC and/or dehydration therapy (47%; 46/99). Nearly all symptoms were eliminated within 24-48 h, whereas using SSC, symptom elimination could take up to seven days or more. The dosage given here (25 mg/kg) was sufficient for turtles in this study, but the use of a higher dosage (50-100 mg/kg) for those animals experiencing severe symptoms may be considered. These types of fast-acting treatment plans are necessary for rehabilitation facilities that are already resource-limited. Intravenous lipid emulsion therapy has the potential to reduce rehabilitation time, save resources, and increase survival of sea turtles and other marine animals experiencing brevetoxicosis.

Systematic review of reptile reproductive toxicology to inform future research directions on endangered or threatened species, such as sea turtles

Threatened 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.

A systematic review of waterborne and water-related disease in animal populations of Florida from 1999-2019

BACKGROUND

Florida's waters are a reservoir for a host of pathogens and toxins. Many of these microorganisms cause water-related diseases in people that are reportable to the Florida Department of Health. Our objective in this review was to ascertain which water-related pathogens and toxins of public health importance have been found in animal populations in Florida over the last twenty years.

METHODS

Nineteen databases were searched, including PubMed and Web of Science Core Collection, using keywords and search terms for the waterborne diseases, water-related vector-borne diseases, and water-based toxins reportable to the Florida Department of Health. For inclusion, peer-reviewed journal articles were to be written in English, published between January 1, 1999 and December 31, 2019, and contain primary research findings documenting at least one of the water-related pathogens or toxins of interest in an animal population within Florida during this same time frame.

RESULTS

Of over eight thousand initial search results, 65 studies were included for final analysis. The most common animal types implicated in the diseases of interest included marine mammals, fish and shellfish, wild birds, and livestock. Toxins or pathogens most often associated with these animals included toxin-producer Karenia brevis, vibriosis, Escherichia coli, and Salmonellosis.

DISCUSSION/CONCLUSION

Findings from this review elucidate the water-related disease-causing pathogens and toxins which have been reported within animal populations in recent Florida history. As most of these diseases are zoonotic, our results suggest a One Health approach is necessary to support and maintain healthy water systems throughout the state of Florida for the protection of both human and animal populations.

Field rates of Sivanto™ (flupyradifurone) and Transform® (sulfoxaflor) increase oxidative stress and induce apoptosis in honey bees (Apis mellifera L.)

Pesticide exposures can have detrimental impacts on bee pollinators, ranging from immediate mortality to sub-lethal impacts. Flupyradifurone is the active ingredient in Sivanto™ and sulfoxaflor is the active ingredient in Transform®. They are both relatively new insecticides developed with an intent to reduce negative effects on bees, when applied to bee-attractive crops. With the growing concern regarding pollinator health and pollinator declines, it is important to have a better understanding of any potential negative impacts, especially sub-lethal, of these pesticides on bees. This study reports novel findings regarding physiological stress experienced by bees exposed to field application rates of these two insecticides via a Potter Tower sprayer. Two contact exposure experiments were conducted-a shorter 6-hour study and a longer 10-day study. Honey bee mortality, sugar syrup and water consumption, and physiological responses (oxidative stress and apoptotic protein assays) were assessed in bees exposed to Sivanto™ and Transform®, and compared to bees in control group. For the longer, 10-day contact exposure experiment, only the Sivanto™ group was compared to the control group, as high mortality recorded in the sulfoxaflor treatment group during the shorter contact exposure experiment, made the latter group unfeasible to test in the longer 10-days experiment. In both the studies, sugar syrup and water consumptions were significantly different between treatment groups and controls. The highest mortality was observed in Transform® exposed bees, followed by the Sivanto™ exposed bees. Estimates of reactive oxygen/nitrogen species indicated significantly elevated oxidative stress in both pesticide treatment groups, when compared to controls. Caspase-3 protein assays, an indicator of onset of apoptosis, was also significantly higher in the pesticide treatment groups. These differences were largely driven by post exposure duration, indicating sub-lethal impacts. Further, our findings also emphasize the need to revisit contact exposure impacts of Sivanto™, given the sub-lethal impacts and mortality observed in our long-term (10-day) contact exposure experiment.

Harmful algal and cyanobacterial toxins in foraging green turtles (Chelonia mydas) in Florida's Big Bend

Numerous toxin-producing harmful algal (HAB) species occur in Florida's coastal waters. Exposure to these toxins has been shown to have sublethal effects in sea turtles. The objective of this study was to establish concentrations of 10 HAB toxins in plasma samples from green turtles (Chelonia mydas) foraging in Florida's Big Bend. Domoic acid, lyngbyatoxin-A, microcystins, nodularin, and okadaic acid were detected, demonstrating exposure to these HAB toxins, which are also a public health concern.

Blood analytes of immature Kemp's ridley sea turtles (Lepidochelys kempii) from Georgia, USA: reference intervals and body size correlations

Health assessments of wildlife species are becoming increasingly important in an ever-changing environment. Kemp's ridley sea turtles (Lepidochelys kempii; hereafter, Kemp's ridleys) are critically endangered and incur several on-going threats to their population recovery; therefore, it is imperative to advance the understanding of baseline blood analyte data as a diagnostic and monitoring tool. For in-water, trawl-captured, immature Kemp's ridleys (minimum N = 31) from Georgia, USA, the objectives of this study were to (1) establish reference intervals (RIs) for packed cell volume (PCV) and 27 plasma biochemistry analytes and (2) determine length-specific relationships in blood analytes. We observed significant positive correlations between minimum straight carapace length and PCV, amylase, calcium:phosphorus ratio, cholesterol, magnesium, triglycerides, total solids, total protein and all protein fractions (e.g. alpha-, beta- and gamma-globulins); aspartate aminotransferase and chloride showed significant negative relationships. These results suggest that certain blood analytes in Kemp's ridleys change as these animals grow, presumptively due to somatic growth and dietary shifts. The information presented herein, in due consideration of capture technique that may have impacted glucose and potassium concentrations, represents the first report of blood analyte RIs for Kemp's ridley sea turtles established by guidelines of the American Society for Veterinary Clinical Pathology and will have direct applications for stranded individuals in rehabilitative care and for future investigations into the health status of wild individuals from this population.

Host-parasite interaction as a toxicity test endpoint using asymmetrical exposures

Interspecific relationships frequently determine the effect a pollutant can have on an organism, and this is especially true in closely interacting species such as hosts and parasites. The high spatial and temporal variability of contaminant concentrations combined with the movement of aquatic biota can further influence the consequences that are associated with contamination. We used a full factorial design for the exposed and unexposed partners of the relationship between the parasitic larvae (glochidia) of the European freshwater mussel (Anodonta anatina) and its host fish (Squalius cephalus) to identify the sources of variation in the sublethal endpoints of species interaction (the intensity of parasite attachment, the spatial position of glochidia on the host body, and encapsulation success). We used the water-borne human pharmaceutical compounds methamphetamine (a central nervous system stimulant) and tramadol (an opioid) at environmentally relevant concentrations (˜ 6.7 and 3.8 nmol L^-1 of methamphetamine and tramadol, respectively) as a proxy for contaminant exposure because these compounds are emerging aquatic stressors that are known for high spatial and temporal variability in their detected concentration levels. The relationship between the bivalve and the fish species was influenced by the preceding contact with both methamphetamine and tramadol, but this effect was highly asymmetric. Our experimental design enabled us to identify the specific changes in the relationship outcome that are elicited by the exposure of individual partners, such as the significant increase in glochidia infection success rate from 59.6 ± 3.9% to 78.7 ± 2.8% (means ± s.e.) that was associated with host exposure to methamphetamine. Additionally, the significant interaction effect of the exposure was demonstrated by the lowered proportion of glochidia attached to gills after the coexposure of both partners to tramadol. The impact of pharmaceuticals on wild aquatic host-parasite relationships provides an example of the risks that are associated with the unintentional discharge of biologically active compounds into freshwater habitats. Given the increasing evidence showing the ecological impact of waste pharmaceuticals, the use of multitrophic interaction endpoints after joint and unilateral exposures provides an important step towards the realistic risk assessment of these compounds.

Assessing Karenia brevis red tide as a mortality factor of sea turtles in Florida, USA

Data on Karenia brevis red tides (≥105 cells l-1) and on dead or debilitated (i.e. stranded) Kemp's ridleys Lepidochelys kempii, loggerheads Caretta caretta, green turtles Chelonia mydas, hawksbills Eretmochelys imbricata, and leatherbacks Dermochelys coriacea documented in Florida during 1986-2013 were evaluated to assess red tides as a sea turtle mortality factor. Unusually large numbers of stranded sea turtles were found coincident with red tides primarily along Florida's Gulf coast but also along a portion of Florida's Atlantic coast. These strandings were mainly adult and large immature loggerheads and Kemp's ridleys, and small immature green turtles and hawksbills. Unusually large numbers of stranded leatherbacks never coincided with red tide. For the 3 most common species, results of stranding data modeling, and of investigations that included determining brevetoxin concentrations in samples collected from stranded turtles, all indicated that red tides were associated with greater and more frequent increases in the numbers of stranded loggerheads and Kemp's ridleys than in the number of stranded green turtles. The mean annual number of stranded sea turtles attributed to K. brevis red tide was 80 (SE = 21.6, range = 2-338). Considering typical stranding probabilities, the overall mortality was probably 5-10 times greater. Red tide accounted for a substantial portion of all stranded loggerheads (7.1%) and Kemp's ridleys (17.7%), and a smaller portion of all stranded green turtles (1.6%). Even though K. brevis red tides occur naturally, the mortality they cause needs to be considered when managing these threatened and endangered species.

Immune effects of the neurotoxins ciguatoxins and brevetoxins

Ciguatoxins (CTXs) and brevetoxins (PbTxs) are phycotoxins that can accumulate along the marine food chain and thus cause seafood poisoning in humans, namely "ciguatera fish poisoning" (CFP) and "neurotoxic shellfish poisoning" (NSP), respectively. CFP is characterized by early gastrointestinal symptoms and typical sensory disorders (paraesthesia, pain, pruritus and cold dysaesthesia), which can persist several weeks and, in some cases, several months or years. NSP is considered a mild form of CFP with similar but less severe symptoms. After inhaled exposure, PbTxs can also cause respiratory tract irritation in healthy subjects and asthma exacerbations in predisposed subjects, whose respiratory functions may be disrupted for several days following PbTx inhalation. Mechanistically, it is well established that CTX- or PbTx-induced disturbances are primarily mainly due to voltage-gated sodium channel activation in sensory and motor peripheral nervous system. However, little is known about the pathophysiology or a potential individual susceptibility to long lasting effects of CFP/NSP. In addition to their action on the nervous system, PbTxs and CTXs were also shown to exert effects on the immune system. However, their role in the pathophysiology of syndromes induced by CTX or PbTx exposure is poorly documented. The aim of this review is to inventory the literature thus far on the inflammatory and immune effects of PbTxs and CTXs.

Potential effects of brevetoxins and toxic elements on various health variables in Kemp's ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtles after a red tide bloom event

Natural biotoxins and anthropogenic toxicants pose a significant risk to sea turtle health. Documented effects of contaminants include potential disease progression and adverse impacts on development, immune function, and survival in these imperiled species. The shallow seagrass habitats of Florida's northwest coast (Big Bend) serve as an important developmental habitat for Kemp's ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtles; however, few studies have been conducted in this area. Our objectives were (1) to evaluate plasma analytes (mass, minimum straight carapace length, body condition index [BCI], fibropapilloma tumor score, lysozyme, superoxide dismutase, reactive oxygen/nitrogen species, plasma protein electrophoresis, cholesterol, and total solids) in Kemp's ridleys and green turtles and their correlation to brevetoxins that were released from a red tide bloom event from July-October 2014 in the Gulf of Mexico near Florida's Big Bend, and (2) to analyze red blood cells in Kemp's ridleys and green turtles for toxic elements (arsenic, cadmium, lead, mercury, selenium, thallium) with correlation to the measured plasma analytes. Positive correlations were observed between brevetoxins and α₂-globulins in Kemp's ridleys and α₂- and γ-globulins in green turtles, indicating potential immunostimulation. Arsenic, cadmium, and lead positively correlated with superoxide dismutase in Kemp's ridleys, suggesting oxidative stress. Lead and mercury in green turtles negatively correlated with BCI, while mercury positively correlated with total tumor score of green turtles afflicted with fibropapillomatosis, suggesting a possible association with mercury and increased tumor growth. The total tumor score of green turtles positively correlated with total protein, total globulins, α₂-globulins, and γ-globulins, further suggesting inflammation and immunomodulation as a result of fibropapillomatosis. Lastly, brevetoxin concentrations were positively related to tumor score, indicating potential tumor promotion by brevetoxin. These results signify that brevetoxins and toxic elements elicit various negative effects on sea turtle health, including immune function, oxidative stress, and possibly disease progression.

Tissue uptake, distribution and excretion of brevetoxin-3 after oral and intratracheal exposure in the freshwater turtle Trachemys scripta and the diamondback terrapin Malaclemys terrapin

Harmful algal blooms (HABs) occur nearly annually off the west coast of Florida and can impact both humans and wildlife, resulting in morbidity and increased mortality of marine animals including sea turtles. The key organism in Florida red tides is the dinoflagellate Karenia brevis that produces a suite of potent neurotoxins referred to as the brevetoxins (PbTx). Despite recent mortality events and rehabilitation efforts, still little is known about how the toxin directly impacts sea turtles, as they are not amenable to experimentation and what is known about toxin levels and distribution comes primarily from post-mortem data. In this study, we utilized the freshwater turtle Trachemys scripta and the diamondback terrapin, Malaclemys terrapin as model organisms to determine the distribution, clearance, and routes of excretion of the most common form of the toxin, brevetoxin-3, in turtles. Turtles were administered toxin via esophageal tube to mimic ingestion (33.48μg/kg PbTx-3, 3×/week for two weeks for a total of 7 doses) or by intratracheal instillation (10.53μg/kg, 3×/week for four weeks for a total of 12 doses) to mimic inhalation. Both oral and intratracheal administration of the toxin produced a suite of behavioral responses symptomatic of brevetoxicosis. The toxin distributed to all organ systems within 1h of administration but was rapidly cleared out over 24-48h, corresponding to a decline in clinical symptoms. Excretion appears to be primarily through conjugation to bile salts. Histopathological study revealed that the frequency of lesions varied within experimental groups with some turtles having no significant lesions at all, while similar lesions were found in a low number of control turtles suggesting another common factor(s) could be responsible. The overall goal of this research is better understand the impacts of brevetoxin on turtles in order to develop better treatment protocols for sea turtles exposed to HABs.