Development of Plasma Vitellogenin Assay for Estrogenic Effects of Endocrine-Disrupting Chemicals Using Ovariectomized Goldfish (Carassius auratus)

Plasma vitellogenin (VTG) assay was developed using ovariectomized goldfish (Carassius auratus) for determining the estrogenic effects of endocrine-disrupting chemicals. In a laboratory study, we assessed the estrogenic activity of commercial fish diets by using a diet for ornamental carp (CD) and a casein-based formulated fish diet (FD), which was shown to not contain soybean or fish meal in a previous study. In ovariectomized fish, plasma VTG concentrations were significantly higher in the CD-fed group than in the FD-fed group. These results indicate that the estrogen activity of CD may be high enough to cause induction of plasma VTG in ovariectomized goldfish as previously observed in male goldfish. Moreover, the effect of estrogen on plasma VTG induction was confirmed by significant plasma VTG production following the exposure of FD-fed ovariectomized goldfish to a nominal estradiol-17β concentration of 100 μg/l for 31 days. Our data suggest that induction of plasma VTG using ovariectomized goldfish is a good tool for evaluating the estrogenic effects of endocrine-disrupting chemicals

Density and abundance of the Freshwater Pearl Mussel, Margaritifera margaritifera, in the Kennebecasis River, New Brunswick and evidence of recent recruitment

Freshwater Pearl Mussel, Margaritifera margaritifera (L., 1758) populations are endangered or threatened throughout Europe, and those in eastern Canada are believed to be some of the most abundant populations remaining worldwide. Although M. margaritifera occurs widely in Atlantic Canada, there is little information to allow its conservation status in the region to be assessed or to place these populations in a global context. Using 0.25 m2 survey quadrats, maximum densities of M. margaritifera in six mussel beds on the Kennebecasis River and a tributary in southeastern New Brunswick were found to range from 12 to 200 m-2. Mean densities at the five mainstem sites ranged from to 1.9 m-2 (SE±0.4) to 16.0 m-2 (±4.3). Mean density on the tributary stream was 1.2 m-2 (SE±0.7). Abundance of M. margaritifera at the six sites ranged from 4,536 (SE±2,600) to 55,520 (SE±14,768) and together the six mussel beds supported an estimated 161,315 Freshwater Pearl Mussels. The presence of juvenile M. margaritifera as small as 11.5 mm at the most upstream site, and Freshwater Pearl Mussels <30 mm at all sites, indicates that there had been recruitment of M. margaritifera juveniles in the Kennebecasis River in the 4–6 years prior to the 2007–2008 study

Pollution and parasitism in aquatic animals: a meta-analysis of effect size

Numerous studies have indicated that aquatic pollution affects parasite populations and communities. However, the responses of individual taxa and functional groups to specific contaminants, and their effect sizes, have yet to be assessed quantitatively. We began by summarizing general trends in the literature, and found that reports of significant changes in parasitism were most commonly observed in response to eutrophication and metal contamination. Among parasite taxa, significant changes were most commonly reported for acanthocephalans, digeneans and microparasites. We then conducted a quantitative meta-analysis of the effects of pollution on parasitism in aquatic animals. We calculated signed standardized effect sizes (as Cohen\u27s d) for all published studies that provided the necessary descriptive statistics, and compared them among major contaminant types (pesticides, hydrocarbons, polychlorinated biphenyls, pulp mill effluent, metals, sewage, eutrophication, and acidification) and parasite taxa (Acanthocephala, Cestoda, Digenea, Monogenea, Nematoda and microparasites). Effect sizes were not significantly different from zero for many parasite/contaminant interactions, and tended to be highly variable within individual taxa. However, consistently strong, significant negative effects were noted in Digenea and Monogenea, especially in response to metal pollution. Significant effect sizes were typically negative, indicating that pollutants have negative effects on parasite populations. Contaminants also had a slightly negative effect on community richness. When parasites were grouped into heteroxenous (with \u3e1 obligatory host in life cycle) vs. monoxenous (1 obligatory host in life cycle) taxa, the latter were more susceptible to a wide range of pollutants. Similarly, directly exposed (external parasites and the free-living transmission stages of internal parasites) and freshwater taxa were more susceptible to a wider range of pollutants than indirectly exposed (internal parasites) and marine taxa. This meta-analysis represented a first attempt to consider the size of the effect of pollution on parasites, and highlighted the potential of susceptible parasite taxa, communities, and functional groups for use in the biological assessment of pollution. For instance, our results indicate that freshwater monogeneans and digeneans are good candidates as potential biological indicators of pollution in aquatic ecosystems

Exposure to a mixture of zinc and copper decreases survival and fecundity of Discocotyle sagittata (Leuckart) parasitizing juvenile Atlantic salmon, Salmo salar L

We assessed the effects of zinc and copper on freshwater monogenean ectoparasites (Discocotyle sagittata Leuckart) infecting juvenile Atlantic salmon (Salmo salar L.). Exposure to 47 microg/L zinc and 3 microg/L copper reduced survival and fecundity of adult D. sagittata, while egg hatching success was only reduced at high exposure concentrations (2704 microg/L zinc and 164 microg/L copper). Parasitized salmon had decreased plasma chloride, but this was negated in infected fish exposed to metals. No other effects on Atlantic salmon survival and physiology (plasma osmolality, hematocrit) were noted, suggesting that D. sagittata may be more susceptible to metal toxicity than its host fish