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The objective of this work was to compare seasonal variations of reproduction physiology of the ragworm Nereis diversicolor --a key species in estuarine ecosystems--originating from a clean (Authie) and multi-polluted (Seine) estuaries. A particular attention was carried out in female worms, on relationships between sexual maturity stages, energy reserves (glycogen and lipids) and steroid hormone levels (progesterone, 17beta-estradiol, and testosterone). Sexual maturity index (SMI), energy reserves and steroid hormones are clearly influenced by season in worms from both sites. Depleted steroid hormone levels were depicted in specimens exhibiting high sexual maturity stage and energy reserves. Intersite analysis has revealed all over the sampling period:--a sexual precocity in worms from Seine,--glycogen concentrations generally higher in worms from Authie,--no clear tendency for lipids,--no differences in steroid hormone levels. Sexual precocity and lower glycogen levels in Seine could be explained by a specific strategy above all devoted to reproduction in these worms. Chemical stress could be a possible explanation of these observations.

The aim of this study was to investigate, in situ, the temporal effects of urban effluent discharge on energy reserves and steroid hormone levels in the intrasedimentary worm Nereis diversicolor. Results have shown no differences in energy reserves (glycogen, lipids) in organisms originating from a contaminated site (Oued Souss) and a comparatively clean site (Oualidia). Both sites are located on the Moroccan Atlantic coast. In contrast, steroid hormone (progesterone, testosterone, and 17beta-estradiol) levels were significantly decreased in animals from Oued Souss. The differences in the responses suggest that organisms from the polluted site have been exposed to endocrine disruptors.

Estuaries are subject to anthropogenic activities. Because the intrasedimentary worm Nereis diversicolor has ecological characteristics and bioindicator abilities, its use was pertinent in investigating the concepts and cost of tolerance to heavy metals (Cd, Cu, Zn). In this context, two approaches were carried out, performing toxicity tests and estimating energy reserves (glycogen and lipids), in populations originating from a contaminated site (Seine estuary) compared with those from a clean site (Authie estuary). Mean lethal times (LT(50)s) of organisms exposed to zinc from the Seine estuary were higher than those from the Authie estuary, but not of organisms exposed to Cd or Cu. The influence of animal weight and salinity on the sensitivity of worms also was studied. The biggest worms were more tolerant to zinc than the smallest ones, and worms survived longer at a reduced salinity (15 per thousand). Concentrations of glycogen and lipids in each sampling season were higher in specimens from the Authie estuary than in worms from the Seine estuary. No influence of salinity on glycogen and lipid levels was observed. Glycogen concentrations were not influenced by the weight of specimens, whereas lipid concentrations were significantly and positively correlated with weight. In conclusion, worms from the Seine estuary exhibited tolerance to Zn, and the depletion of energy reserves observed in this population could be interpreted as a cost of tolerance., ((c) 2005 Wiley Periodicals, Inc.)