Seasonal gonadal development and age-related maturity patterns of introduced pumpkinseed (Lepomis gibbosus Linnaeus, 1758) in a heated thermal reservoir and an adjacent river reach

Testis and ovarian maturation status, maturity profile and gonado-somatic index (GSI) were assessed in pumpkinseed (Lepomis gibbosus) collected from Mirgenbach, a cooling-water reservoir associated with a nuclear power plant, and from the River Moselle 7km downstream of the reservoir's thermal outflow. Histological investigation indicated that in both sexes, gonadal development of pumpkinseed in the heated reservoir was more advanced than in the cooler Moselle River throughout the breeding season. The histological maturity profile of reservoir males ranked by the advancement of sperm cells was highly correlated with its GSI (rs=0.73, P<0.001). GSI of females in the reservoir increased with the stage at maturity, but GSI was not significantly correlated with total length, age or growth rate of the individual. All sampled individuals of both sexes were mature at age 1 in the heated reservoir, whereas 48% of age 1 males and 57% of age 1 females were not mature in the river. GSI patterns suggest that males in the reservoir adopted one of two reproductive strategies (nesters or cuckolders), whereas no small males with large enough testes to be considered cuckolders were apparent in the river. The warm thermal regime of Mirgenbach Reservoir led to precocial maturity, early season reproduction, and the greater prevalence of apparent cuckolder males than would normally occur in this climatic zone.

Estrogenic effects in crucian carp (Carassius carassius) exposed to treated sewage effluent

To assess the estrogenicity of a municipal sewage treatment plant, sexually mature crucian carp of both sexes were exposed for 28 days to domestic treated sewage effluent running with a constant flow of water, with tap water and with different concentrations of the sewage effluent (25%, 50% and 100%). Vitellogenin (VTG), gonadosomatic index (GSI), hepatosomatic index (HSI), and histological abnormalities were used to assess the estrogenic potency of the effluent. Results show a significant (P<0.05) increase in VTG levels in all exposed male fish. A significant (P<0.05) reduction in the GSI was only observed in fish exposed to 100% effluent. Morphological changes were detected by histological evaluation, revealing severe effects on the testes. Spermatogenesis was progressively reduced to total inhibition in fish exposed to 100% effluent. One of the most pronounced effects detected was the presence of oocytes in male gonads, observed in 20% of males exposed to 100% sewage effluent.

Comparative study of the estrogenic responses of mirror carp (Cyprinus carpio) exposed to treated municipal sewage effluent (Lisbon) during two periods in different seasons

To assess the estrogenic potency of the treated domestic sewage effluent from a sewage treatment plant (STP) located in Lisbon (Chelas), 60 mirror carp (Cyprinus carpio) were exposed to different concentrations of the sewage effluent (0%, 25%, 50% and 100%) for two periods of 28 days in two different seasons (winter/spring). Vitellogenin induction in males was used as a biomarker of exposure to xenoestrogens. At the end of the experiment, blood samples were taken for vitellogenin analysis and the fish were sacrificed and dissected. Gonad samples were taken for histological evaluation of the sewage effects. The results showed an increase in vitellogenin induction in exposed fish, both males and females, depending on the different dilutions of the sewage effluent. In comparison with controls, the gonadosomatic index decreased significantly (P < 0.05) in fish exposed to 100% treated effluent. Although statistically not significant, the hepatosomatic index (HSI) was high in all exposed fish. Histological abnormalities in fish gonads were evaluated and related to the different percentages of sewage effluent. Seasonal variations found in estrogenic responses were attributed to weather influences on sewage dilution.

Étude de la contamination par les métaux lourds du champ d'épandage des eaux usées de la ville de Marrakech (Maroc)

La bioconcentration du Zn, Cu et Cd a été étudiée chez Melanopsis praemorsa L. (Gastéropode prosobranche) provenant de deux sites d'une khettara située dans le champ d'épandage des eaux usées de la ville de Marrakech. Les khettaras représentent un système d'irrigation traditionnel que l'on trouve dans certaines zones arides et semi-arides de la région ouest-paléarctique. L'eau est mise à jour par drainage de la nappe phréatique. Le degré de contamination de ce gastéropode s'avère très élevé et les teneurs métalliques augmentent de l'hiver à l'été. Les causes de la variabilité des concentrations métalliques chez les gastéropodes des deux stations ont été recherchées par des expériences de transplantation, et par des dosages de métaux au niveau du sédiment, de la spirogyre et du périphyton installé sur des substrats artificiels. Les résultats obtenus montrent que les différences entre les concentrations métalliques accumulées par les Melanopsis dans les deux stations pourraient être attribuées à la spéciation du métal dans l'eau. D'autres facteurs peuvent être mis en cause et méritent d'être précisés.

Circulation of copper in the biotic compartments of a freshwater dammed reservoir

This study concerns a chronic copper release in an aquatic ecosystem: Mirgenbach reservoir; which is characterized by high salinity, conductivity and hardness, a eutrophic state and a high temperature. To study the bioavailability of copper in the biotic compartments, the sampling covered the entire food chain (phyto- and zooplankton, macroalgae, aquatic plants, crustaceans, mollusks, and fish). Of the organisms present, the filter feeder Dreissena polymorpha, the detritivorous Bithynia tentaculata and Orconectes limosus were most contaminated by copper. The level of copper found in fish was the lowest. Body copper concentrations recorded in the present study show large variability between species even in some that are closely related. In most cases, however, the metal handling strategy, feeding habits, morphology and ecology can, at least partially, explain the metal content recorded. Pollution factors have been used to assess the state of contamination of the food chain. This study showed finally that the copper in the lake is bioavailable and bioaccumulated by organisms up to high levels and some effects of long-term toxicity of copper on benthic community and planktonic biomass were pointed out.

Mucous cell responses in gill and skin of brown trout Salmo trutta fario in acidic, aluminium-containing stream water

Morphometric examination was carried out on the gills and skin of wild and caged hatchery brown trout Salmo trutta fario in an acidic (pH 4.9 to 5.4; Al 203 to 250 microg l(-1)) and in a non-acidic (pH 6.7 to 7.0; Al 27 to 67 microg l(-1)) stream in the Vosges Mountains (NE France) to assess the sublethal effects of acidic water on the mucous cell response. The caged fish were randomly collected after 2, 4, 7 and 11 d and the wild fish were obtained by electrofishing. After 2 d, a reduction of both mucous cell (MC) number and size was observed in the gills of fish held in the acidic stream, suggesting a massive mucus discharge. Hyperplasia and hypertrophy of cells immediately followed this mucus secretion. In the same fish population, skin examination showed a slight and delayed decrease of MC number but a significant increase of cell size. The number of mucous cells of gills and skin was similar in both wild trout populations, whereas a significant MC hypertrophy was observed in the wild fish of the acidic stream. The present field experiment indicates that caged fish could be useful as early indicators of acidification. In addition, the examination of wild populations suggested the occurrence of adaptive mechanisms, information that might be of importance in the context of river recovery programs.

Trace elements in children's hair, as related exposure in wastewater spreading field of Marrakesh (Morocco)

Lead and cadmium concentration was determined in the hair of 327 school children living in a wastewater spreading field of Marrakesh (Morocco). The influence of age, sex, food habits and family occupation on the children's hair Pb and Cd concentration was also evaluated. Girls had more metal in their hair than boys (16.5 +/- 5.4 micrograms/g and 12.5 +/- 3.5 micrograms/g, respectively). However, for Cd the boys had more metal (2.9 +/- 0.6 and 2.2 +/- 0.4, respectively) but the difference was not statistically significant and metal levels decreased with age. Family occupation, direct contact with wastewater, customs and food habits were the most significant factors influencing the metal content of children's hair. The average Pb and Cd content were higher in the exposed children (14.8 +/- 4.5 micrograms/g and 2.5 +/- 0.5 micrograms/g, respectively) than in the non-exposed children (4.6 +/- 2.2 micrograms/g and 0.6 +/- 0.2, respectively), but the difference was not statistically significant. This study shows that in this area all the population (especially children) was extremely exposed to the danger caused by potentially toxic metals.

Accumulation of extractable organic halogens (EOX) by the freshwater mussel, Anodonta cygnea L., exposed to chlorine bleached pulp and paper mill effluents

Freshwater mussels, Anodonta cygnea L., were collected in a lowly polluted area in north-eastern France, and exposed during 28 days at three sites up and downstream of a chlorine bleached pulp and paper mill effluent Water, sediment and mussel samples were collected at regular intervals and analyzed for halogenated organic residues using the sum parameters AOX (Adsorbable Organic Halogen) and EOX (Extractable Organic Halogen). The survey of the water showed a chronic contamination by organic halogens of the water and the sediment downstream of the pulp and paper mill sewer. Mussels exposed upstream of the mill showed no significant variation of their EOX tissue concentration. In contrast, progressive accumulation of EOX occurred with the exposure time in mussels exposed downstream of the mill. No steady state of the EOX concentration was observed after four weeks of exposure.