Sewage treatment works (STW) effluents throughout the U.K. have been shown to be estrogenic, inducing vitellogenin (VTG) synthesis in caged and wild fish for considerable distances (up to several kilometers) downstream of the effluent discharge. Thresholds for vitellogenin induction in caged fish in those studies have been derived from shortterm exposures, and may not necessarily be representative of thresholds for estrogenic responses in wild fish living in rivers that contain STW effluent. In addition, very little is known about the long-term fluctuations in the concentrations of the estrogenic components of STW effluents. In this paper, it was established that the concentrations of natural steroid estrogens and xenoestrogens (alkylphenolic chemicals) in a treated sewage effluent fluctuated temporally (over 8 months), from between 36 and 308 ng/L and between <0.2 (detection limit) and 10.7 µg/L, respectively. Long-term exposure of maturing adult roach to a graded concentration of this effluent (0, 9.4, 17.5, 37.9, and 100% v/v) demonstrated that the vitellogenic response was both dose and time dependent. After 1 month exposure, the response threshold was 37.9 ( 2.3% treated sewage effluent, whereas after 4 months exposure, a significant induction of VTG occurred at an effluent concentration of 9.4 ( 0.9%. The data presented suggests that estrogenic responses in wild fish living in U.K. rivers cannot necessarily be predicted from short-term exposures using caged fish. The functional significance and/or ecological consequences of induction of vitellogenin resulting from exposure to STW effluent has yet to be determined in wild fish.

Wild roach (Rutilus rutilus) have been found with intersex gonads in rivers throughout the United Kingdom. The incidence of intersexuality is strongly correlated with discharges of estrogenic treated sewage effluent into those rivers, and this has led to the hypothesis that estrogenic chemicals in effluents are feminizing wild male fish. In this study, early-life stage roach (50 days post hatch, dph) were exposed for 150 days to a graded concentration (0%, 12.5%, 25%, 50%, and 100%) of treated sewage (primarily domestic) effluent to examine the effects of exposure on sexual differentiation and development. Measurement of steroid estrogens and alkylphenolic chemicals in the effluent and a resulting dose-dependent induction of vitellogenin (VTG; a female-specific, estrogen-dependent plasma protein) confirmed that the fish had been exposed and responded to "estrogen" in the effluent. Exposure to treated sewage effluent induced feminization of the reproductive ducts in "male" roach in a dose-dependent manner (in full-strength effluent, 100% of the fish had feminized ducts), indicating that the disruption of the gonad ducts seen in wild roach is the result of exposure to treated sewage effluents during early-life stages. There were no effects of treated sewage effluent exposure on germ cell development; therefore, no oocytes occurred in the testes of the feminized male roach. Subsequent, depuration of the effluent exposed fish in "clean" water for 150 days resulted in a reduction in plasma VTG but no alteration of the feminized ducts, indicating that the effect of the treated sewage effluent on reproductive duct development was permanent. The causality of oocytes in the testes of wild male roach therefore remains to be elucidated.

Fish and shellfish are exposed to a wide range of polycyclic aromatic hydrocarbons (PAH) following oil spills at sea, and can become contaminated as a result. Finfish have a more effective mixed-function oxidase enzyme system than shellfish, and are therefore able to metabolise and excrete PAH more effectively than the invertebrates. Thus, contamination by high-molecular weight PAH, including those with carcinogenic potential and so of concern with regard to human consumers, is therefore usually observed in shellfish, and particularly in bivalve molluscs. Oil spills are not the sole source of PAH, however, as parent compounds are also generated by a wide range of combustion processes. In this paper, consideration is given to monitoring data gathered following recent oil spills (both of crude oil and diesel fuel), alongside data from other studies. These include studies conducted around a former gasworks site and downstream of an aluminium smelter in the UK, and from mussel monitoring studies undertaken in the UK and the USA (including the Exxon Valdez oil spill and the National Status and Trends programme), and in other countries in Europe. For comparative purposes the PAH concentrations are summed and also expressed as benzo[a]pyrene equivalents, their relative concentrations being weighted in relation to the carcinogenic potential of individual PAH compounds using toxic equivalency factors (TEF). Our aim was to assess the utility of this approach in fishery resource monitoring and control following oil spills. Certainly this approach seems useful from the data assessed in this study. and the relative ranking of the various studies seems to reflect the relative degree of concern for human consumers due to the differing contamination sources. As a simple tool for control purposes it is equally applicable to PAH derived from oil spills, and from industrial and combustion sources.

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In February 1996, the oil tanker 'Sea Empress' spilt over 70 000 t of crude oil which contaminated ca 200 km of coastline (Milford Haven, Wales, UK). The effects of the oil on immunity in mussels Mytilus edulis were investigated in parallel with the measurement of hydrocarbon contamination in the tissues. Initially, severe immunosuppression occurred in oiled mussels, corresponding with very high polycyclic aromatic hydrocarbon (PAH) levels. The haemocytes of mussels from oiled sites showed significantly reduced superoxide generation and phagocytic activity, effects likely to have deleterious consequences for successful disease resistance. As contaminant levels decreased, the immunosuppression became less extreme and recovery was evident by May 1996. Between October 1996 and March 1997, immune activity in the haemocytes of the previously oiled mussels was again significantly reduced, coinciding with increased PAH levels. During this latter period, certain high molecular mass PAHs (characteristically derived from combustion processes) were primarily responsible for the increase, occurring at similar concentrations in the mussel tissues to those observed just after the spill. A subsequent reduction of hydrocarbons in June 1997 was followed by another, but less marked, increase in PAHs between October 1997 and March 1998, coupled with only minimal changes in immunity. The results show that immunosuppression following the oil spill was severe, but that recovery followed a few months later and the initial effects were not therefore permanent. The results also suggest that seasonal peaks in combustion-derived PAHs may occur in the region and that these would have been greatly exacerbated early in 1996 by oil released from the 'Sea Empress'. KEY WORDS: Mytilus · Immune defence · Haemocyte · Oil spill · Hydrocarbon contaminationResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 206: 155-170, 2000 These include the induction of biomarker enzymes in fish and molluscs (Sole et al. 1996, Woodin et al. 1997, Stagg et al. 1998, Kirby et al. 1999, abnormalities in fish embryos/larvae (Hose et al. 1996, Bue et al. 1998 and haematological changes in vertebrates (Duffy et al. 1994, Walton et al. 1997.Despite the considerable effects that crude oil contaminants can exert on the physiology of marine animals, information concerning impacts on the physiology of natural invertebrate populations is more limited, particularly with respect to their immune defences. Globally, marine invertebrates constitute an important economic resource, and factors influencing their ability to resist disease and hence maintain healthy populations are of considerable relevance. Invertebrate immune defences comprise cellular and humoral components, which are highly efficient in combating pathogens and parasites and share many facets with vertebrate immune defences (Ratcliffe et al. 1985, Engstrøm et al. 1993. Laboratory exposure to contaminants can significantly alter immunity in invertebrates fr...

The tanker "Sea Empress" grounded at the entrance to Milford Haven in February 1996, releasing 72 000 t of Forties blend crude oil and 480 t of heavy fuel oil into the waters of southwest Wales. An estimated 15 000 t of emulsified oil came ashore along 200 km of coastline. A fishery exclusion zone was established to protect consumers of fish and shellfish, and monitoring was instigated in order to establish the degree and spread of contamination. A wide range of further studies were conducted with the aim of assessing the overall impact of the spill. In this paper we report on the establishment and subsequent lifting of fishing restrictions and the results of the fish and shellfish monitoring programme. The application of a range of biological effects techniques which illustrated sublethal impacts is also described. In retrospect, the impact of the spill was much less than would have been expected from the quantity of oil spilled. This was due to the circumstances of the spill, which led to fresh crude oil, amenable to chemical dispersion, being released during each ebb tide and carried into deep water to the south of Milford Haven. This enabled the extensive dispersant spraying operation, which included the aerial application of 446 t of chemical oil dispersant in order to enhance the rate of natural dispersion of the oil. This reduced the impact of the spill by preventing an additional 57 000 to 110 000 t of emulsified oil from impacting the beaches.

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