PCDD/F and PCB levels in different tissues from dugongs (Dugong dugon) inhabiting the Queensland coastline

Bioaccumulation and trophodynamics of cyclic methylsiloxanes in the food web of a large subtropical lake in China

Available information on the bioaccumulation and trophodynamics of cyclic methylsiloxanes in aquatic food webs is insufficient for a reliable understanding of their toxicity and potential ecological harm. The concentrations of four cyclic methylsiloxanes in aquatic species collected from Lake Chaohu (China) were measured and the total concentration was in range of 2.01-36.1 ng/g dry weight. Dodecamethylcyclohexasiloxane (D6) represented 57.7% of the total measured methylsiloxane concentration. The distribution of these methylsiloxanes constitute the first tissue-specific record. The hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) tended to accumulate preferentially in fish muscles, while D6 was preferentially accumulated in fish liver and gills. In Lake Chaohu, significant trophic magnification of D3 (p < 0.01) and dilution of D6 (p < 0.05) were observed, and the trophic magnification factors (TMFs) were estimated at 4.94 and 0.68, respectively. No significant trends in D4 and D5 (p > 0.05) were observed within the food web. This study further confirmed the complexity of trophic transfer of the methylsiloxanes in the aquatic food web. The findings suggest that tissue-specific methylsiloxane distribution in aquatic species might also affect the observed TMFs. More research is required to investigate methylsiloxanes in additional species and their trophodynamics in different food webs.

Distribution and toxicity of persistent organic pollutants and methoxylated polybrominated diphenylethers in different tissues of the green turtle Chelonia mydas

Investigating environmental pollution is important to understand its impact on endangered species such as green turtles (Chelonia mydas). In this study, we investigated the accumulation and potential toxicity of selected persistent organic pollutants (POPs) and naturally occurring MeO-PBDEs in liver, fat, kidney and muscle of turtles (n = 30) of different gender, size, year of death, location and health status. Overall, POP concentrations were low and accumulation was highest in liver and lowest in fat which is likely due to the poor health of several animals, causing a remobilization of lipids and associated compounds. PCBs and p,p'-DDE dominated the POP profiles, and relatively high MeO-PBDE concentrations (2'-MeO-BDE 68 up to 192 ng/g lw, 6-MeO-BDE 47 up to 79 ng/g lw) were detected in all tissues. Only few influences of factors such as age, gender and location were found. While concentrations were low compared to other marine wildlife, biological toxicity equivalences obtained by screening the tissue extracts using the micro-EROD assay ranged from 2.8 to 356 pg/g and the highest values were observed in muscle, followed by kidney and liver. This emphazises that pollutant mixtures found in the turtles have the potential to cause dioxin-like effects in these animals and that dioxin-like compounds should not be overlooked in future studies.

First assessment of POPs and cytochrome P450 expression in Cuvier's beaked whales (Ziphius cavirostris) skin biopsies from the Mediterranean Sea

The Cuvier's beaked whale (Ziphius cavirostris) is one of the least known cetacean species worldwide. The decreasing population trend and associated threats has led to the IUCN categorising the Mediterranean subpopulation as Vulnerable on the Red List of Threatened Species. This study aimed to investigate for the first time the ecotoxicological status of Cuvier's beaked whale in the NW Mediterranean Sea. The study sampled around the 20% of the individuals belonging to the Ligurian subpopulation, collecting skin biopsies from free-ranging specimens. The levels of polychlorinated biphenyl (PCBs), polybrominated diphenyl ethers (PBDEs) and induction of cytochrome's P450 (CYP1A1 and CYP2B isoforms) were evaluated. Results highlighted that the pattern of concentration for the target contaminants was PCBs > PBDEs and the accumulation values were linked to age and sex, with adult males showing significantly higher levels than juvenile. Concerns raised by the fact that 80% of the individuals had PCB levels above the toxicity threshold for negative physiological effects in marine mammals. Therefore, these findings shed light on this silent and serious threat never assessed in the Mediterranean Cuvier’s beaked whale population, indicating that anthropogenic pressures, including chemical pollution, may represent menaces for the conservation of this species in the Mediterranean Sea.

Relevance of current PCB concentrations in edible fish species from the Mediterranean Sea

Legal restrictions and bans have led to a steady decrease in PCB environmental concentrations. Yet, in recent years PCBs have been found at very high levels in the Mediterranean Sea, for instance, in some apex predators. This work aimed to investigate current PCB (eighteen congeners: #28,52,77,81,101,105,114,118,123,126,138,153,156,157,167,169,180,189) concentrations in the Mediterranean Sea and their relevance today, focusing on their occurrence in edible fish species typically consumed in the Mediterranean diet. In spring 2017, a total of 48 fish samples from the Northern Thyrrenian Sea were collected: 16 specimens of sardine (Sardina pilchardus), 16 of anchovy (Engraulis encrasicolus) and 16 of bogue (Boops boops). PCBs were quantified in the muscle of the animals by means of GC-QqQ-MS. They were found in all samples at the greatest concentrations (ng/g w.w.) in sardine (4.15-17.9, range), and very similar values between anchovy (1.01-7.08) and bogue (1.46-7.22). WHO-TEQ PCB values followed the same order, i.e. sardine (0.410-1.24, range in pg/g w.w.) > anchovy (0.0778-0.396) ~ bogue (0.0726-0.268). These concentrations lied below the European limits of 75 ng/g (w.w.) for the six indicator PCBs and 6.5 pg/g WHO-TEQ for dioxins and dioxin-like PCBs in muscle meat of fish. Additionally, estimated weekly intakes (EWI, in pg WHO-TEQ/Kg/week) for sardine (1.2), anchovy (0.29) and bogue (0.35) scored below the safe value proposed by EFSA of 2 pg WHO-TEQ/Kg/week. When comparing with data reported for the same species in previous Mediterranean studies, values found here were lower than those surveyed in the late 90s and early 2000s; however, they were often not notably different from concentrations reported in last years. This builds up on the concept of a current slow decrease of PCBs in the Mediterranean Sea, likely linked to new inputs and/or remobilization of burdens, and reinforces the need of continous monitoring of these legacy contaminants still ubiquitous today.

Assessment of PCDD/Fs, dioxin-like PCBs and PBDEs in Mediterranean striped dolphins

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.

Concentrations of legacy persistent organic pollutants and naturally produced MeO-PBDEs in dugongs (Dugong dugon) from Moreton Bay, Australia

Dugongs (Dugong dugon) are an iconic and strictly herbivorous species. They inhabit coastal areas, which brings them in contact with urban and agricultural pollutant sources, yet their exposure and susceptibility to environmental pollutants is still largely unknown. The goal of this study was to investigate the presence of several legacy compounds such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and pesticides as well as naturally produced MeO-PBDEs in male and female dugongs from Moreton Bay (n = 24), a semi-enclosed embayment close to Australia's third largest city, Brisbane. Results show that concentrations of all investigated compounds are low in general (<120 ng/g lipid weight) and below known toxicity thresholds established for marine mammals. However, concentrations found in this study are higher or comparable to concentrations in dugongs outside Moreton Bay or in sirenians worldwide. No temporal trends for POPs from 2001 until 2012 were found for adult animals suggesting that environmental changes are only slowly reflected in dugongs. Finally, pollutant profiles in dugongs are limited to the most persistent PCBs, pesticides and PBDEs that also dominate POP profiles in other marine mammal species in general.