Levels of short and medium chain length polychlorinated n-alkanes in environmental samples from selected industrial areas in England and Wales.

Electron capture or negative ion chemical ionisation gas chromatography-mass spectrometry was employed to measure concentrations of short and medium chain length polychlorinated n-alkanes extracted from samples of water, river sediment, benthos, fish, soil, digested sewage and earthworms. Analysis of samples from 20 aquatic and eight agricultural sites indicated that short and medium chain length polychlorinated alkanes were present in the following concentration ranges: sediment < 0.2-65.1 mg/kg dry weight, water < 0.1-1.7 micrograms/l, fish < 0.1-5.2 mg/kg wet weight, benthos < 0.05-0.8 mg/kg wet weight, digested sewage 1.8-93.1 mg/kg dry weight, soil < 0.1 mg/kg dry weight, and earthworms < 0.1-1.7 mg/kg wet weight. It is clear from this study that these compounds are widely distributed in the UK environment, although it is not yet possible to fully assess the risks posed to either wildlife or humans by their continued use. Further study of these compounds is indicated.

Organochlorine contaminants in Caspian and harbour seal blubber.

Organochlorine contaminants (pesticides and individual polychlorinated biphenyl congeners, PCBs) were measured in Caspian (Phoca caspica) seal blubber and compared with concentrations in Harbour (Phoca vitulina) seal blubber. Concentrations of total dichlorodiphenyltrichloroethane (DDT) and its metabolites were significantly higher in Caspian seal than Harbour seal samples, whereas PCB congeners were significantly higher in Harbour than Caspian seals. Our finding suggests that Caspian seals are exposed to high levels of DDT pesticides. In contrast, PCBs are circulating in this population at much lower levels than in marine mammals from the North Sea.

Investigating potential associations between chronic exposure to polychlorinated biphenyls and infectious disease mortality in harbour porpoises from England and Wales.

Bioaccumulation of immunosuppressive organochlorines like polychlorinated biphenyls (PCBs) may pose a threat to the health and viability of cetacean populations. To investigate possible associations between chronic exposure to PCBs and infectious disease mortality in harbour porpoises Phocoena phocoena in UK waters, blubber concentrations of 25 individual chlorobiphenyl (CB) congeners in 34 healthy harbour porpoises that died due to physical trauma (mainly by-catch) were compared with CB concentrations in 33 animals that died due to infectious disease. The infectious disease group had significantly greater total 25 CBs (sigma 25CBs) concentrations than the physical trauma group (P < 0.001). The mean sigma 25CBs concentration in animals that died due to physical trauma was 13.6 mg kg-1 extractable lipid whereas the mean concentration in the infectious disease group was 31.1 mg kg-1 extractable lipid. The relationship between higher sigma 25CBs and the infectious disease group was not confounded by age, sex, nutritional status, season, location or year of stranding. In addition, adult females had significantly lower sigma 25CBs levels than adult males (P < 0.05) due to maternal transfer of CBs to offspring. These findings are consistent with the hypothesis that chronic PCB exposure predisposes harbour porpoises in UK waters to infectious disease mortality, although further research is required to test these associations more robustly.

Organochlorine levels in common seals (Phoca vitulina) which were victims and survivors of the 1988 phocine distemper epizootic.

We compared concentrations of organochlorines in the blubber of common seals (Phoca vitulina) found dead during the 1988 phocine distemper epizootic with levels in animals which survived it. There were highly significant differences between the live and dead animals, and between sample sites. These were not fully accounted for by seasonal and condition-related changes in blubber thickness.

Uptake of organochlorines (chlorobiphenyls, dieldrin; total PCB & DDT) in bottlenose dolphins (Tursiops truncatus) from Cardigan Bay, west Wales.

High concentrations of organochlorine compounds (particularly PCB and chlorobiphenyls) have been found in three bottlenose dolphins from the vicinity of New Quay in West Wales. Although few in number, the animals ranged in age from 10 months to 23 years. The occurrence of high contaminant concentrations in all of these animals suggests that a high level of uptake of these compounds occurs in food after weaning as well as by transfer from mother to calf. In order to investigate this further we have tried to model the uptake using a bioenergetics-based approach. Using estimates of feeding rate we have calculated the concentrations of these contaminants in average prey items necessary to maintain the dolphin's body burden during the juvenile growth stage. The data available to date are too few for a rigorous test of this approach, however these preliminary studies suggest that the contaminant concentrations in local food items analysed to date are not sufficiently high to explain the high concentrations found in dolphin blubber. Further information is needed on the contaminant burdens of bottlenose dolphins in Cardigan Bay, and of their relationships and diet (including seasonal and migratory components), in order to validate this approach.

Polybrominated diphenyl ethers in two species of marine top predators from England and Wales.

During an earlier study, polybrominated diphenyl ethers were detected at high concentrations in fish and sediments downstream of a manufacturing site in NE England. We have now undertaken analysis of 14 tri- to heptabromodiphenyl ether congeners in tissues of two species of marine top predators exposed to these compounds through their consumption of fish. In this paper we report data for 47 cormorants and 60 harbour porpoises from England and Wales, sampled during the period 1996-2000. Concentrations of the summed congeners ranged from 1.8 to 140 microg kg(-1) wet weight in cormorant livers, and from not detected to 6900 microg kg(-1) wet weight in porpoise blubber. The major congeners present were generally BDE47, BDE99 and BDE100. There was little correlation between concentrations of chlorobiphenyls (as the sum of 25 individual congeners) and the sum of the 14 BDE congeners determined, particularly for the porpoises.

Measurement of stress effects (scope for growth) and contaminant levels in mussels (Mytilus edulis) collected from the Irish Sea.

The objective of this research was to quantify the impact of pollution along the coastlines of the Irish Sea. Pollution assessment was based on the combined measurement of scope for growth (SFG), and chemical contaminants in the tissues of mussels (Mytilus edulis) collected from 38 coastal sites around the Irish Sea during June-July in 1996 and 1997. On the UK mainland coast, the SFG showed a general trend with a significant decline in water quality in the Liverpool and Morecambe Bay region. High water quality was recorded along the west coast of Wales, as well as southwest England and northwest Scotland (clean reference sites outside the Irish Sea). Along the coast of Ireland there was a similar trend with reduced SFG within the Irish Sea region. SFG was generally low north of Duncannon and then improved north of Belfast. The poor water quality on both sides of the Irish Sea is consistent with the prevailing hydrodynamics and the spatial distribution of contaminants associated with urban/ industrial development. The decline in SFG of mussels on both sides of the Irish Sea was associated with a general increase in contaminant levels in the mussels. Certain contaminants, including PAHs, TBT, sigmaDDT, Dieldrin, gamma-HCH, PCBs, and a few of the metals (Cd, Se, Ag, Pb), showed elevated concentrations. Many of these contaminants were particularly elevated in the coastal margins of Liverpool Bay, Morecambe Bay and Dublin Bay. A quantitative toxicological interpretation (QTI) of the combined tissue residue chemistry and SFG measurements indicated that at the majority of coastal sites, c. 50 to > 80% of the observed decline in SFG was due to PAHs as a result of fossil fuel combustion and oil spills. TBT levels were highest at major ports and harbours, but these concentrations only made a minor contribution to the overall reduction in SFG. At no sites were individual metals accumulated to concentrations that could cause a significant effect on SFG. The study identified many sites where the observed reduction in SFG was far greater than predicted from the limited number of chemical contaminants analysed, thus indicating the presence of additional 'unknown toxicants'. Sewage (containing domestic, agricultural and industrial components) appears to be an important contributor to reduced SFG and linear alkylbenzenes (LABs) and As may provide suitable 'sewage markers'. There was a highly significant positive correlation between SFG and As (P < 0.001). This relationship may be due to reduced As uptake by algal food material and mussels at sites with elevated P04 concentrations (e.g. at sites with sewage inputs). Phosphate is a known competitive inhibitor of As accumulation, at least in algae. The results highlight that further research is required on 'sewage markers' in mussels. The SFG approach therefore provides a rapid, cost-effective and quantitative measure of pollution impact, as well as a means of identifying the causes through a QTI of tissue contaminants levels. It also serves to identify the presence of unidentified toxicants and areas that require further study.

Mass mortality of common dolphins (Delphinus delphis) in south west England due to incidental capture in fishing gear.

In the first quarter of 1992, 118 dolphin carcases, of which 54 were positively identified as common dolphins (Delphinus delphis), were found stranded on the coast of Cornwall and Devon. To determine the cause, detailed post mortem examinations were carried out on 38 of the carcases, and the results were compared with those from 20 common dolphins that stranded on the coast of Cornwall and Devon in the previous 15 months. There was no evidence that the deaths were due to an infectious or parasitic disease, or acute intoxication by any of the algal toxins, trace metals or chlorinated hydrocarbons measured. However, 30 of the 38 dolphins showed signs associated with incidental capture in fishing gear. Skin lesions characteristic of capture in a small-meshed net and the predominance of recently ingested Atlantic mackerel (Scomber scombrus) and pilchard (Sardina pilchardus) in the stomachs of the dolphins suggested that they had been caught in the trawl or purse seine nets used for these fish. There is insufficient information to explain why this high mortality occurred in 1992 and not in other years.

The relationship between polychlorinated biphenyls in blubber and levels of nematode infestations in harbour porpoises, Phocoena phocoena.

Post-mortem examinations of harbour porpoises, Phocoena phocoena, regularly reveal heavy parasitic worm burdens. These same post-mortem records show varying levels of polychlorinated biphenyls (PCBs) accumulating in the blubber of porpoises. Although a number of papers have documented geospatial and temporal changes of PCBs and their detrimental effects on marine mammal health, as yet none have examined their role in determining nematode burdens in wild marine mammal populations. Using a data set consisting of harbour porpoises stranded in the UK between 1989 and 2002, we found a significant, positive association between PCB levels and nematode burdens, although the nature of the relationship was confounded with porpoise sex, age and cause of death. It was also apparent that individuals with the heaviest infestations of nematodes did not have the highest PCB level: while PCBs are important, they are clearly not the sole determinants of nematode burdens in wild populations of the harbour porpoise around the UK.

Concentration-dependent changes of PCB patterns in fish-eating mammals: structural evidence for induction of cytochrome P450.

Data sets on CB concentrations in fish-eating mammals from five laboratories were combined to test and refine a pharmacokinetic model. Clear differences in PCB patterns were observed between species. The ability to metabolize chlorobiphenyl (CB) congeners with vicinal H-atoms only in the ortho- and meta-positions and with one ortho-chlorine substituent generally increased in the order otter < cetaceans (harbor porpoise, common dolphin) < phocid seals (harbor and grey seal), but the metabolism of congeners with vicinal H-atoms in the meta- and para-positions and with two ortho-chlorines increased in the order cetaceans < seals < otter. Both categories of congeners are probably metabolized by different families of cytochrome P450 (1A and 2B) of which levels apparently differed between the cetaceans, the pinnipeds, and the otter. Within-species CB patterns differed in a concentration-dependent manner. The induction of cytochrome P450 enzymes offers the most likely explanation for this phenomenon, but starvation could have a similar effect on occasion.