Endocrine effects in Gammarus fossarum (Amphipoda): influence of wastewater effluents, temporal variability, and spatial aspects on natural populations.

In a field study, individuals of autochthounous populations of the amphipod Gammarus fossarum were examined for their maturity status, oocyte development, and biochemical parameters associated with their reproductive cycle. Variability in these parameters was related to abiotic exposure parameters varying in accordance to wastewater discharges, stream identity, and time. Patterns of all investigated parameters showed predominantly seasonal rather than spatial influence for both exposure and biologic effects. Single selected-effect parameters, however--such as the maturity index, late vitellogenic oocyte size and atresia, and the hsp90 level--responded to a sewage treatment plant discharge showing an estrogenic potential and also correlated significantly with the concentration of potential xenoestrogens at the different locations.