Assessment of Phthalate Esters and Physiological Biomarkers in Bottlenose Dolphins (Tursiops truncatus) and Killer Whales (Orcinus orca).

There is growing concern about the potential adverse health effects of phthalates (PAEs) on human health and the environment due to their extensive use as plasticizers and additives in commercial and consumer products. In this study, we assessed PAE concentrations in serum samples from aquarium-based delphinids (Tursiops truncatus, n = 36; Orcinus orca, n = 42) from California, Florida, and Texas, USA. To better understand the physiological effects of phthalates on delphinids, we also explored potential correlations between phthalates and the biomarkers aldosterone, cortisol, corticosterone, hydrogen peroxide, and malondialdehyde while accounting for sex, age, and reproductive stage. All PAEs were detected in at least one of the individuals. ΣPAE ranges were 5.995-2743 ng·mL-1 in bottlenose dolphins and 5.372-88,675 ng·mL-1 in killer whales. Both species displayed higher mean concentrations of DEP and DEHP. PAEs were detected in newborn delphinids, indicating transference via placenta and/or lactation. Linear mixed model results indicated significant correlations between aldosterone, month, location, status, and ΣPAEs in killer whales, suggesting that aldosterone concentrations are likely affected by the cumulative effects of these variables. This study expands on the knowledge of delphinid physiological responses to PAEs and may influence management and conservation decisions on contamination discharge regulations near these species.

Metal and metalloid maternal transfer in a newborn West Indian manatee (Trichechus manatus) two years after the northeastern oil spill disaster of 2019 in Brazil.

A large-scale oil spill along the northeastern Brazilian coast in 2019-2020 severely impacted primary manatee habitats in Brazil. This study aimed to assess metal and metalloid contamination in a dead manatee calf found following this oil spill. Several elements were detected, including chromium, iron, nickel, lead, and vanadium, which are crude oil components, and thallium, a component of dispersants used to degrade and dissipate crude oil. The presence of these contaminants in the manatee calf is indicative of maternal exposure, metabolism, and newborn transference via placenta and lactation. This is the first report of mother-calf metal transfer in manatees, highlighting the species' vulnerability and potential long-term population dynamics effects, and the first report for several metals and metalloids in these animals, laying the foundation for future research efforts. These findings highlight the urgent need for continued environmental monitoring, ecotoxicological assessments, and conservation initiatives.

Assessing variation in faecal glucocorticoid concentrations in gray whales exposed to anthropogenic stressors.

Understanding how individual animals respond to stressors behaviourally and physiologically is a critical step towards quantifying long-term population consequences and informing management efforts. Glucocorticoid (GC) metabolite accumulation in various matrices provides an integrated measure of adrenal activation in baleen whales and could thus be used to investigate physiological changes following exposure to stressors. In this study, we measured GC concentrations in faecal samples of Pacific Coast Feeding Group (PCFG) gray whales (Eschrichtius robustus) collected over seven consecutive years to assess the association between GC content and metrics of exposure to sound levels and vessel traffic at different temporal scales, while controlling for contextual variables such as sex, reproductive status, age, body condition, year, time of year and location. We develop a Bayesian Generalized Additive Modelling approach that accommodates the many complexities of these data, including non-linear variation in hormone concentrations, missing covariate values, repeated samples, sampling variability and some hormone concentrations below the limit of detection. Estimated relationships showed large variability, but emerging patterns indicate a strong context-dependency of physiological variation, depending on sex, body condition and proximity to a port. Our results highlight the need to control for baseline hormone variation related to context, which otherwise can obscure the functional relationship between faecal GCs and stressor exposure. Therefore, extensive data collection to determine sources of baseline variation in well-studied populations, such as PCFG gray whales, could shed light on cetacean stress physiology and be used to extend applicability to less-well-studied taxa. GC analyses may offer greatest utility when employed as part of a suite of markers that, in aggregate, provide a multivariate measure of physiological status, better informing estimates of individuals' health and ultimately the consequences of anthropogenic stressors on populations.

Effects of vessel traffic and ocean noise on gray whale stress hormones.

Human use of marinescapes is rapidly increasing, especially in populated nearshore regions where recreational vessel traffic can be dense. Marine animals can have a physiological response to such elevated human activity that can impact individual health and population dynamics. To understand the physiological impacts of vessel traffic on baleen whales, we investigated the adrenal stress response of gray whales (Eschrichtius robustus) to variable vessel traffic levels through an assessment of fecal glucocorticoid metabolite (fGC) concentrations. This analysis was conducted at the individual level, at multiple temporal scales (1-7 days), and accounted for factors that may confound fGC: sex, age, nutritional status, and reproductive state. Data were collected in Oregon, USA, from June to October of 2016-2018. Results indicate significant correlations between fGC, month, and vessel counts from the day prior to fecal sample collection. Furthermore, we show a significant positive correlation between vessel traffic and underwater ambient noise levels, which indicates that noise produced by vessel traffic may be a causal factor for the increased fGC. This study increases knowledge of gray whale physiological response to vessel traffic and may inform management decisions regarding regulations of vessel traffic activities and thresholds near critical whale habitats.

Assessment of fecal steroid and thyroid hormone metabolites in eastern North Pacific gray whales.

Baleen whale fecal samples have high potential for endocrine monitoring, which can be used as a non-invasive tool to identify the physiological response to disturbance events and describe population health and vital rates. In this study, we used commercial enzyme-linked immunosorbent assays to validate and quantify fecal steroid (progestins, androgens and glucocorticoids) and thyroid hormone metabolite concentrations in eastern North Pacific gray whales (Eschrichtius robustus) along the Oregon coast, USA, from May to October of 2016-2018. Higher mean progestin metabolite concentrations were observed in postweaning females, followed by pregnant females. Mean androgen, glucocorticoid and thyroid metabolites were higher in mature males. Progestin, glucocorticoids and thyroid fecal metabolites varied significantly by year, with positive correlations between progestin and androgen, and between glucocorticoid and thyroid metabolites. We also present two case studies of a documented injured whale and a mature male displaying reproductive competitive behavior, which provide reference points for physiologically stressed individuals and adult breeding males, respectively. Our methods and findings advance the knowledge of baleen whale physiology, can help guide future research on whale physiology and can inform population management and conservation efforts regarding minimizing the impact of anthropogenic stressors on whales.

Occurrence and tissue distribution of organochlorinated compounds and polycyclic aromatic hydrocarbons in Magellanic penguins (Spheniscus magellanicus) from the southeastern coast of Brazil.

Seabirds are suitable biomonitors for several persistent organic pollutants (POP), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs), although scarce studies of PAHs in seabirds are available, especially in South American populations. Therefore, this study aimed to assess OCPs, PCBs and PAHs, through gas chromatography-electron capture detector (GC-ECD) and gas chromatography-mass spectrometry (GC-MS) analyses, in liver (n = 9) and muscle tissue (n = 13) from juvenile Magellanic penguins (Spheniscus magellanicus) found stranded on the coast of Rio de Janeiro, Southeastern Brazil. DDT-related compounds were the most frequently detected OCP, and 4,4'-dichlorodiphenyldichloroethylene (DDE), the main DDT metabolite found in penguin tissues. OCP concentrations in liver were two-fold higher than in muscle tissues. Compound specific ratios identified recent exposure of penguins to some OCPs as well as evidence of legacy pollution associated with industrial sources. The predominant PCB congeners were PCB 8/5, PCB 138/160 and PCB 153/132, with concentrations ranging from

Total and subcellular Ti distribution and detoxification processes in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil.

Titanium (Ti), used in many dailyuse products, such as shampoos and sunscreen filters, in the form of TiO2 nanoparticles (NPs), may elicit adverse marine biota effects. Marine mammal Ti data is scarce, and subcellular distribution and detoxification information is non-existent. Ti concentrations and metalloprotein detoxification in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil were assessed. Metallothionein (MT) concentrations were determined spectrophotometrically, total and subcellular Ti, by ICP-MS and detoxification, by HPLC-ICP-MS. Ti detoxification occurred through MT complexation. Statistical Ti-MT associations were observed in S. bredanensis liver, indicating TiO2 NPs contamination, as Ti binds to MT only as NPs. MT-Ti correlations were observed for both the coastal (P. blainvillei) and offshore (S. bredanensis) dolphins, evidencing oceanic TiO2 diffusion. Ti detoxification through binding to reduced glutathione occurred in both species. Thermostable subcellular fractions are a valuable tool for cetacean Ti detoxification assessments and should be applied to conservation efforts.

Subcellular metal distributions and metallothionein associations in rough-toothed dolphins (Steno bredanensis) from Southeastern Brazil.

Metals are subject to internal subcellular compartmentalization, altering their bioavailability. Thus, subcellular metal assessments are crucial in biomonitoring efforts. Metal distribution in three subcellular fractions (insoluble - ISF, thermolabile - TLF and thermostable - TSF) were determined by ICP-MS in Steno bredanensis specimens from Southeastern Brazil. Associations between metals, metallothionein (MT) and reduced glutathione (GSH) were also investigated. Differential metal-detoxification mechanisms were observed. MT detoxification was mostly noted for As, Cd, and Pb, while Cu, Cr, Hg, Ni, Se and Ti displayed lower MT-associations. Fe, Zn and Se, on the other hand, were poorly associated to MT, and mostly present in the ISF, indicating low bioavailability. This is the first report on subcellular Sn and Ti distribution in cetaceans and the first in this species in Brazil. Potential protective roles of essential metals against toxic elements are postulated. This study indicates that important biochemical detoxification information is obtained through subcellular fraction analyses in marine mammals.

Interspecific variation of essential and non-essential trace elements in sympatric seabirds.

Chemical pollution is a growing issue for ocean ecosystems, threatening especially apex predators because they bioaccumulate persistent chemical pollutants such as non-essential trace elements. The trophic position is thus a key aspect when assessing the impacts of environmental pollution in marine organisms. Here we investigate the differences in the concentrations of essential (Cu, Cr, Se, and Zn) and non-essential elements (Hg, Al, As, Cd, and Sr), in muscular and hepatic tissues of four sympatric non-migratory seabirds (namely Sula leucogaster, Larus dominicanus, Fregata magnificens, and Thalasseus acuflavidus), which were found stranded along the Brazilian coast. The observed hepatic and muscular interspecific differences in elemental concentrations indicated that these sympatric seabirds are differently exposed to persistent contaminants circulating in the food web due to differences with respect to known feeding behaviours and prey preferences. Moreover, we found a consistent co-accumulative relationship between Se and Hg molar levels in liver tissues with mean Se:Hg molar ratio above 1. This relationship supports previous studies indicating that Se, via the formation of SeHg complexes, plays an essential biochemical role in the detoxification process of methyl mercury in seabirds. Our results suggest that feeding behaviour is an important factor associated to the interspecific differences of trace element concentrations in seabirds. However, traits other than feeding preferences (e.g. age) may also play an important role in the accumulation of these elements.

Variation in mercury concentration in juvenile Magellanic penguins during their migration path along the Southwest Atlantic Ocean.

The vulnerability of seabirds related to their migratory dynamics is frequently linked to environmental problems along the migration path. In this context, Magellanic penguins (Sphenicus magellanicus) seem to be vulnerable to an extensive range of environmental disturbances during their northward migration along the Atlantic waters of South America, which include by catch, marine debris ingestion, overfishing and environmental contamination. In this study, we investigate mercury accumulation in muscle and hepatic tissues of juveniles penguins collected along the Brazilian coast during three migratory seasonal years (2006, 2008 and 2012) and three areas along a latitudinal gradient. We found significant differences in Hg levels across the years, with higher hepatic Hg levels found in tissues of penguins sampled in 2008. The higher Hg levels in samples of penguins from 2008 might be attributed to variations in body condition or Hg uptake, associated with the trophic imbalance linked to an extreme El Niño event during that year. Significant differences in Hg accumulation across the latitudinal areas were also observed. The penguins sampled at the farthest area from the breeding ground presented the higher levels of Hg and also the poorest body condition. Body condition and other traits may influence the levels of chemical pollutants and decrease the migratory success rate in the juvenile age phase, compromising population dynamics.