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Intersex (ovotestis) is the condition whereby an individual possesses oocytes, at varying degrees of severity, within the normal testicular tissue and is regarded as an endpoint of endocrine disruption in male fish. The occurrence of intersex has been linked with exposure to endocrine-disrupting compounds present in the environment, which are thought to mimic the actions of the female sex hormone 17-b-oestradiol. Using stained histological sections of archived cases of intersex from European flounder (Platichthys flesus), this study developed a grading method to assess the extent of the condition. This was termed the ovotestis severity index (OSI). The OSI utilizes the distribution pattern (focal, diffuse, cluster, zonal) and type of oocyte (previtellogenic, cortical alveolar, vitellogenic) to assign a severity rating to each intersex fish. A high OSI refers to fish with testicular material almost completely replaced with mature (vitellogenic) oocytes, and lower scores indicate those fish with small numbers of immature (previtellogenic) oocytes. The development of this index provides pathologists with a robust tool for the grading of the intersex condition in European flounder and potentially in other fish species. [ABSTRACT FROM AUTHOR]

Plasma vitellogenin (VTG) concentrations and the presence of the ovo-testis (intersex) condition have been recorded in male flounder (Platichthys flesus) captured from several United Kingdom (UK) estuaries since 1996 as part of the endocrine disruption in the Marine Environment (EDMAR) project and earlier programs. It has been confirmed that plasma VTG concentrations in male flounder have remained elevated in several UK estuaries (e.g., Tees, Mersey, and Tyne) throughout the period covered by this study. However, the time-series data indicate that plasma VTG, a measure of environmental estrogen contamination, has decreased in fish captured from several estuaries, especially those of the Tyne and Mersey. Shorter time-series data sets from the Forth and Clyde estuaries also suggest a decrease in estrogen contamination at these sites. Trends associated with specific point sources of estrogenic contamination show site-specific patterns. For instance, plasma VTG levels in male flounder captured near the Howdon sewage treatment outfall (Tyne) have shown a steady decline to near baseline levels in 2001, while the plasma of male fish captured at a site adjacent to the Dabholm Gut discharge in the Tees estuary have shown little evidence of a sustained decline. The occurrence of the intersex condition was detected at a low but consistent prevalence through the study period, with the majority of cases recorded in fish captured from the Tyne and Mersey estuaries. The data set does not allow conclusions to be drawn about any temporal trends associated with this condition. The significance of the findings and possible mitigating influences are discussed in terms of the impacts on wild fish and the role of effluent treatment in reducing these. [ABSTRACT FROM AUTHOR]

A battery of biomarkers is often used to evaluate the effects of exposure to chemical contaminants and detect responses to environmental stress. Unfortunately, field application of biomarkers is subject to various constraints (e.g., the availability of living material) that can limit data acquisition and prevent the use of multivariate methods during statistical analysis. In these circumstances, a simple method is needed to summarize biomarker responses and simplify their interpretation in biomonitoring programs. The present study used star plots to display results for the panel of biomarkers used for each station and survey. Integrated biomarker response (IBR) was then computed as the star plot area. Star plots using IBR values instead of biomarker data make it possible to visualize between-site and/or between-survey differences for comparison with exposure conditions. This approach was applied to sites in the Baltic Sea and the Seine Estuary, English Channel. In both cases, IBR values were visually compared to polycyclic aromatic hydrocarbons (PAH) or polychlorobiphenyls (PCB) levels measured in mussel or fish tissues. The IBR, as an indicator of environmental stress, appears to be a useful tool for scientists and managers in assessing ecological risk. [ABSTRACT FROM AUTHOR]

Estrogenic discharges are known or suspected to be present in many United Kingdom estuaries and are also occurring from offshore oil and gas installations. The aim of this study was to establish whether estrogens and their mimics are present in marine waters at concentrations that can produce biological responses in fish and, if so, to discover whether the effects are likely to be harmful to populations and communities through changes in reproductive and other physiological processes. Laboratory studies and extensive field surveys were carried out with the euryhaline flounder (Platichthys flesus), using the amount of yolk protein vitellogenin in the blood of free-living male fish as an indicator of exposure to estrogens. Exposure to the synthetic estrogen ethynylestradiol for 3 weeks confirmed that the vitellogenin response was made and showed that this species is about one order of magnitude less sensitive than the freshwater species rainbow trout. The fish did not respond to the estrogen mimic nonylphenol at concentrations of 30 g/L. Wild male flounder were sampled from four contaminated United Kingdom estuaries: the Tyne, Crouch, Thames, and Mersey. Fish from one or more sites in each estuary had significantly elevatedconcentrations of vitellogenin in their blood when compared to concentrations in fish from the clean control estuary (Alde River). Vitellogenin concentrations in the Tyne and Mersey fish were four and six orders of magnitude greater, respectively, than control concentrations. Elevated vitellogenin concentrations were also seen in some male flounder caught in coastal areas. Approximately 20% of male fish from the Mersey estuary contained oocytes in their testes, but this intersex condition was not seen elsewhere. The implications of these findings for fish populations are discussed. [ABSTRACT FROM AUTHOR]