Perfluoroalkyl substances (PFASs) are a class of organohalogenated compounds of environmental concern due to similar characteristics as the well-studied legacy persistent organic pollutants (POPs) that typically show environmental persistence, biomagnification and toxicity. Nevertheless, PFAS are still poorly regulated internationally and in many aspects poorly understood. Here, we studied liver and muscle concentrations in five cetacean species stranded at the southeastern coast of Spain during 2009–2018. Twelve of the fifteen targeted compounds were detected in >50% of the liver samples. Hepatic concentrations were significantly higher than those in muscle reflecting the particular toxicokinetics of these compounds. Bottlenose dolphins Tursiops truncatus showed the highest hepatic ΣPFAS (n = 5; 796.8 ± 709.0 ng g⁻¹ ww) concentrations, followed by striped dolphin Stenella coeruleoalba (n = 29; 259.5 ± 136.2 ng g⁻¹ ww), sperm whale Physeter macrocephalus (n = 1; 252.8 ng g⁻¹ ww), short-beaked common dolphin Delphinus delphis (n = 2; 240.3 ± 218.6 ng g⁻¹ ww) and Risso’s dolphin Grampus griseus (n = 1; 78.7 ng g⁻¹ ww). These interspecies differences could be partially explained by habitat preferences, although they could generally not be related to trophic position or food chain proxied by stable N (δ¹⁵N) and C (δ¹³C) isotope values, respectively. PFAS profiles in all species showed a similar pattern of concentration prevalence in the order PFOS>PFOSA>PFNA≈PFFUnA>PFDA. The higher number of samples available for striped dolphin allowed for evaluating their PFAS burden and profile in relation to the stranding year, stable isotope values, and biological variables including sex and length. However, we could only find links between δ¹⁵N and PFAS burdens in muscle tissue, and between stranding year and PFAS profile composition. Despite reductions in the manufacturing industry, these compounds still appear in high concentrations compared to more than two decades ago in the Mediterranean Sea and PFOS remains the dominating compound.

This study aimed at comparing toxic element (Hg, Cd) bioaccumulation in relation to age for bottlenose (Tursiops truncatus) and striped dolphins (Stenella coeruleoalba) from Mediterranean and Atlantic waters. Metal concentrations were also measured in selected prey to infer metal exposure through the diet. As expected, Mediterranean prey exhibited the highest Hg levels, probably as a consequence of the Hg enrichment of the Mediterranean Sea. Comparing the predators from each area and taking age into account, Mediterranean bottlenose dolphins displayed higher Hg levels than Atlantic dolphins (p = 0.032), whereas Mediterranean striped dolphins did not (p = 0.691). The consumption of Myctophid fish, which showed the highest Hg levels (105 +/- 80 ng g(-1) w.wt.) among Atlantic prey, may explain the high Hg levels in the liver of the Atlantic striped dolphins and suggested a preferential offshore feeding behaviour in this area. Concerning Cd, no clear differences were found between geographical areas. (c) 2006 Elsevier Ltd. All rights reserved.

Litter is a well-known problem for marine species; however, we still know little about the extent to which they're affected by microplastics. In this study, we analyse the presence of this type of debris in Western Mediterranean striped dolphins' intestinal contents over three decades. Results indicated that frequency was high, as 90.5% of dolphins contained microplastics. Of these microplastics, 73.6% were fibres, 23.87% were fragments and 2.53% were primary pellets. In spite of the high frequency of occurrence, microplastic amount per dolphin was relatively low and highly variable (mean ± SD = 14.9 ± 22.3; 95% CI: 9.58–23.4). Through FT-IR spectrometry, we found that polyacrylamide, typically found in synthetic clothes, was the most common plastic polymer. Here, we establish a starting point for further research on how microplastics affect this species' health and discuss the use of striped dolphins as indicators of microplastics at sea.

Bio-accumulation of high levels of persistent organic pollutants represent a serious conservation concern for Mediterranean marine odontocetes. In this study, blubber samples from 10 striped dolphins (Stenella coeruleoalba) stranded along the Italian coasts during 2015–2016 were analyzed. All specimens showed dl-PCBs > PBDEs ≫ PCDD/Fs. Median concentrations were 1820 ng/g l.w., 456 ng/g l.w. and 23.9 pg/g l.w., respectively. dl-PCBs accounted for 93.3% of total TEQs. PBDE concentrations suggest that the Mediterranean basin may be considered a hotspot for organobromine compounds. OCDD did not represent the greatest contributor to PCDD/Fs profile, most likely due to a change in dioxin environmental sources in the last two-three decades. Despite international regulations, the present study emphasized that POP exposure levels in Mediterranean striped dolphins have not declined significantly in recent years. Toxicological and risk assessment studies on this sentinel species may provide an early indication of potential adverse health effects on Mediterranean ecosystems.

This study provides information on baseline concentrations of the radionuclides Cesium-137, Potassium-40 and Polonium-210 in sea mammals from the Baltic Sea. The radionuclides were analyzed in the liver, kidney and muscle of harbor porpoises, striped dolphins, and gray and ringed seals from the Polish coast by γ- and α-spectrometry. Median 137Cs activities were 14.8, 13.2 and 23.2Bqkg−1 w.w. in the liver, kidney and muscles, respectively. Activities of 40K and 210Po in the respective tissues were found to be 79.1, 79.8 and 111Bqkg−1 for 40K and 58.1, 59.2 and 32.9Bqkg−1 for 210Po. The measured 137Cs concentrations were extraordinarily high in comparison to those reported in sea mammals from other locations. However, dose assessments did not imply health effects from 137Cs exposure in Baltic Sea mammals. Correlations between 137Cs tissue activities and reported sea water concentrations highlight the potential use of marine mammals for biomonitoring purposes.

Wild animals in their natural environment could provide a big source of information, but sampling can be very challenging, above all for protected species, like marine mammals. Nevertheless, significant data can be obtained sampling stranded animals right after their death, taking into account proper sampling time and methodology.RNA samples from the skin of 12 individuals including the species Stenella coeruleoalba, Tursiops truncatus, and Grampus griseus were used to test 4 potential gene markers of anthropogenic contaminants exposure. The individuals were sampled in 3 geographic areas: the Adriatic, Ionian and Tyrrhenian seas. Three out of the 4 genes tested showed higher expression in the samples collected from the Adriatic Sea. Minute skin samples tell the story of the specific geographic location where the marine mammal spent its life, thanks to the different impact on gene expression exerted by different contamination levels.

Concentrations of Hg, Se, Cd, Cu, Zn, Fe, Mn and As, in kidney, liver, muscle and blubber from 7 specimens of Stenella coeruleoalba, stranded along the Israeli Mediterranean coast (IMC) from 2006 to 2011 (2011-series) were determined and compared to previous data on S. coeruleoalba from the IMC (2001-series). No differences were observed in essential and toxic elements concentrations, between the two series, except for hepatic Mn which was higher in the latter. Hg/Se molar ratios in blubber, kidney and liver increased linearly with log Hg concentrations, while muscle was more heterogenic in this respect. Means (±SD) of hepatic Hg concentrations (134±89 and 181±200mgkg−1, from the 2011 and 2001 series, respectively) were similar to that found in 2007–2009 specimens from Spain, possibly reflecting the relatively high natural background levels of mercury in the Mediterranean Sea.