Assumpció Borrell

CONGENER PROFILE AND TOXICITY ASSESSMENT OF POLYCHLORINATED BIPHENYLS IN DOLPHINS, SHARKS AND TUNA COLLECTED FROM ITALIAN COASTAL WATERS

Abstract Bottlenose and Rissos dolphins found dead along the Italian coast in 1992 were analysed for the presence of PCB isomers and DDT. High concentrations of PCBs (90–1400 μg/g wet wt) were detected in the blubber of stranded carcasses. The concentrations were higher than those found in animals showing reproductive failure and physiological impairment following prolonged PCB exposure, suggesting that the contamination by PCBs as well as DDT may be a major causative factor for the large-scale deaths of dolphins in the Mediterranean Sea. The 2,3,7,8-TCDD toxic equivalents estimated for bottlenose and Rissos dolphins were 18.8 and 20.8 ng/g, respectively, with a major contribution from mono-ortho PCBs. The monoortho congeners of IUPAC Nos 105, 118 and 156 accounted for most of the toxicity exerted by PCBs in these dead dolphins. An increase in the proportion of non-ortho coplanar PCB congener of IUPAC No. 169 to No. 126 with an increase in the total PCB concentration in the blubber suggested a strong induction of drug metabolizing enzymes. It is possible to use CB-169 CB-126 concentration ratio to indicate whether there has been a strong activation of cytochrome P450 enzyme system in severely exposed/contaminated dolphin populations. The total PCB concentrations in the adipose fat of sharks from Italian coasts ranged from 70 to 4000 ng/g wet wt and that of DDT from 14 to 300 ng/g wet wt. In bluefin tuna, the total PCB and DDT concentrations were 170–2200 and 56–780 ng/g wet wt, respectively. These values were comparable to those reported for the same species in the Mediterranean Sea during the 1970s, suggesting the existence of PCB sources near this marine ecosystem.

Isomer-specific analysis and toxic evaluation of polychlorinated biphenyls in striped dolphins affected by an epizootic in the western Mediterranean sea.

Isomer-specific concentrations of polychlorinated biphenyls (PCBs) including planar, mono- and di-ortho congeners and concentrations of DDT were determined in striped dolphins affected by a morbillivirus epizootic in the western Mediterranean in 1990. Extremely high concentrations of PCBs ranging from 94 to 670 μg/g (wet wt) were detected in the blubber. Similarly, DDT concentrations were high, between 22 and 230 μg/g (wet wt). The concentrations of three non-ortho coplanar PCBs were 43 (3,3′,4,4′-T4CB), 6.8 (3,3′,4,4′,5-P5CB), and 7.8 (3,3′,4,4′,5,5′-H6CB) ng/g (wet wt), respectively, the highest residue levels reported to date. The estimated 2,3,7,8-TCDD toxic equivalents of non-, mono- and di-ortho PCB congeners in striped dolphins were several times higher than those observed for other marine mammals and humans. Mono-ortho congeners contributed greater 2,3,7,8-TCDD toxic equivalents than non-ortho members. The higher ratio of 3,3′,4,4′,5,5′-H6CB/3,3′,4,4′,5-P5CB (IUPAC 169/126) suggested a strong induction of mixed function oxidase enzymes and highlighted the possibility of using this ratio as an index for risk assessment of PCB contamination in marine mammals. Elevated concentrations of PCBs may have played a role in the immune depression in striped dolphins, ultimately leading to the development of morbillivirus disease.

Age trends and reproductive transfer of organochlorine compounds in long-finned pilot whales from the Faroe Islands.

Total DDT and PCB concentrations were determined in blubber of 130 long-finned pilot whales, Globicephala melas (100 females and 30 males) from the Faroe Islands (northern north-east Atlantic). In males and immature females no relation was observed between age and organochlorine concentrations or the ratio of tDDT (total DDT)/PCB; in contrast, concentrations and ratios in mature females declined with age, which is attributed to reproductive transfer to their offspring during gestation and lactation. Relative abundance of DDE respective to tDDT increased in males and young females and decreased in mature females. Organochlorine transfer to offspring during lactation was found to represent about 60-100% of the mothers body load, while that occurring during gestation was estimated to be much lower, in the range 4-10% of mothers body load. Transfer rates tended to decrease with mothers age and were, consequently, much higher in primiparous females than in those that had already given birth. Transplacental rates were found to be consistent with the ratio between mothers body weight and neonatal body weight.

Massive Consumption of Gelatinous Plankton by Mediterranean Apex Predators

Stable isotopes of carbon and nitrogen were used to test the hypothesis that stomach content analysis has systematically overlooked the consumption of gelatinous zooplankton by pelagic mesopredators and apex predators. The results strongly supported a major role of gelatinous plankton in the diet of bluefin tuna (Thunnus thynnus), little tunny (Euthynnus alletteratus), spearfish (Tetrapturus belone) and swordfish (Xiphias gladius). Loggerhead sea turtles (Caretta caretta) in the oceanic stage and ocean sunfish (Mola mola) also primarily relied on gelatinous zooplankton. In contrast, stable isotope ratios ruled out any relevant consumption of gelatinous plankton by bluefish (Pomatomus saltatrix), blue shark (Prionace glauca), leerfish (Lichia amia), bonito (Sarda sarda), striped dolphin (Stenella caerueloalba) and loggerhead sea turtles (Caretta caretta) in the neritic stage, all of which primarily relied on fish and squid. Fin whales (Balaenoptera physalus) were confirmed as crustacean consumers. The ratios of stable isotopes in albacore (Thunnus alalunga), amberjack (Seriola dumerili), blue butterfish (Stromaeus fiatola), bullet tuna (Auxis rochei), dolphinfish (Coryphaena hyppurus), horse mackerel (Trachurus trachurus), mackerel (Scomber scombrus) and pompano (Trachinotus ovatus) were consistent with mixed diets revealed by stomach content analysis, including nekton and crustaceans, but the consumption of gelatinous plankton could not be ruled out completely. In conclusion, the jellyvorous guild in the Mediterranean integrates two specialists (ocean sunfish and loggerhead sea turtles in the oceanic stage) and several opportunists (bluefin tuna, little tunny, spearfish, swordfish and, perhaps, blue butterfish), most of them with shrinking populations due to overfishing.

PCB and DDT in blubber of cetaceans from the northeastern north Atlantic

Abstract Blubber from long-finned pilot whales, Atlantic white-sided dolphins and harbour porpoises caught off the Faroe Islands, and from fin whales, sei whales, and sperm whales from Iceland were analysed for organochlorine pollutants. Pollutant levels were positively correlated with increasing trophic level and inversely with body size. For any given species, the %DDE/Σp,p′-DDT ratio increased with Σp,p′-DDT burden, probably reflecting increased detoxification activity of liver enzymes at higher contaminant concentrations. The %Σp,p′-DDT/PCB ratio decreased with increasing trophic level suggesting differential transfer rates of the two organochlorine groups through food webs. Because of the effect of transfer of organochlorines through gestation and lactation, Σp,p′-DDT and PCB levels, %DDE/Σp,p′-DDT and %Σp,p′-DDT/PCB ratios were higher in males than in females.

Bioaccumulation of polychlorinated biphenyls (PCBs) and dichlorodiphenylethane (DDE) methyl sulfones in tissues of seal and dolphin morbillivirus epizootic victims

Polychlorinated biphenyl (PCB) and dichlorodiphenylethane (DDE) methyl sulfone (MSF) metabolites possess high affinities for binding two homologous 16,000 Da homodimeric receptor proteins in the lung (Clara cell secretory protein, CCSP) and the uterus (uteroglobin, UG), leading to selective bioaccumulation of MSFs in these tissues. As marine mammals are highly exposed to organochlorines, concentrations of PCBs, PCB MSFs, DDT, and DDE MSF were analyzed in blubber, lung, and uterus samples from harbor seal (Phoca vitulina) and striped dolphin (Stenella coeruleoalba

Overfishing of small pelagic fishes increases trophic overlap between immature and mature striped dolphins in the Mediterranean Sea.

The interactions among diet, ecology, physiology, and biochemistry affect N and C stable isotope signatures in animal tissues. Here, we examined if ecological segregation among animals in relation to sex and age existed by analyzing the signatures of δ15N and δ13C in the muscle of Western Mediterranean striped dolphins. Moreover, we used a Bayesian mixing model to study diet composition and investigated potential dietary changes over the last two decades in this population. For this, we compared isotope signatures in samples of stranded dolphins obtained during two epizootic events occurring in 1990 and 2007–2008. Mean δ13C values for females and males were not significantly different, but age-related variation indicated δ13C enrichment in both sexes, suggesting that females and males most likely fed in the same general areas, increasing their consumption of benthic prey with age. Enrichment of δ15N was only observed in females, suggesting a preference for larger or higher trophic level prey than males, which could reflect different nutritional requirements. δ13C values showed no temporal variation, although the mean δ15N signature decreased from 1990 to 2007–2008, which could indicate a dietary shift in the striped dolphin over the last two decades. The results of SIAR indicated that in 1990, hake and sardine together contributed to 60% on the diet of immature striped dolphins, and close to 90% for mature striped dolphins. Conversely, the diet of both groups in 2007–2008 was more diverse, as hake and sardine contributed to less than 40% of the entire diet. These results suggest a dietary change that was possibly related to changes in food availability, which is consistent with the depletion of sardine stocks by fishing.