| The goal of the field study was to assess the effects of sediment contaminants on the main components of the vitellogenic cycle in winter flounder, and determine seasonal and inter-annual variations. The objectives of the laboratory experiment were to monitor the complete reproductive cycle of winter flounder in captivity, confirm that contaminated sediments alone could cause adverse effects to winter flounder reproduction and validate non-destructive sampling of fish for the purpose of bimonitoring.;The field work aspect of this research took place in Sydney Harbour (Nova Scotia, Canada), which is one of the most polycyclic aromatic hydrocarbon contaminated estuaries (PAH) in North America. Five stations were selected representing a gradient of bottom sediment PAH concentrations ranging from 200 ppm to less than detectable. Serum estradiol concentrations were found to be significantly reduced in fish captured at stations with sediment PAH concentrations at or above 10 ppm. In the same way, egg maturation was significantly retarded for part of the reproductive cycle in fish from the same stations. Furthermore, between 25% and 30% of the fish from the two most contaminated sites (50 ppm and 200 ppm) did not spawn. Female serum vitellogenin concentrations were inconclusive, but a significant increase of serum vitellogenin in males was measured. This phenomenon correlated positively with sediment PAH concentrations, suggesting the possibility of an estrogenic effect of the contamination.;In the laboratory, an attempt was made at reproducing the conditions found in the Sydney Estuary. Contrary to the field results, vitellogenin concentrations tended to be more sensitive than estradiol in detecting significant differences between treatments and suggested the existence of an estrogenic effect at the intermediate PAH concentration (41 ppm). The number of fish failing to spawn correlated positively with the level of contamination in the tank, ranging from less than 10% to more than 30%, similar to field results. (Abstract shortened by UMI.)... |
