Specimens of the Sydney rock oyster Saccostrea commercialis were deployed for a 3-month period at control and sewage disturbed marine locations in the Hunter Region, New South Wales, Australia. The DNA damage product,8-hydroxyguanine, was measured by GC/MS-SIM from chromatin extracts of the gill tissues of oysters to assess oxidative damage. The levels ranged from 11.5 to 18.8 modified bases per 10(7) guanine bases. Although the condition indices were significantly different between the Redhead control site (178.3+/-3. 6) and the Burwood sewage disturbed location (140.4+/-4.4), no significant differences in 8-hydroxyguanine concentrations were detected between the sites, and the concentration of 8-hydroxyguanine was not correlated to condition index. However, levels of the DNA base modification were correlated with the concentrations of bioaccumulated lead (r=0.84, P=0.036). This association provides in vivo evidence that the bioaccumulation of lead results in oxidative damage to DNA. An additional control and sewage disturbed site were included to investigate the relationship between heavy metal bioaccumulation and the condition index of deployed oysters. After the 3-month deployment period, the condition index was negatively correlated to concentrations of bioaccumulated mercury (r=-0.80, P<0.001), cobalt (r=-0.65, P<0.01), and nickel (r=-0.69, P<0.01), suggesting a strong negative influence of these metals at relatively low concentrations on the physiological condition of the oysters.
Sydney rock oysters, Saccostrea commercialis, were deployed for a 3-month period at sewage-disturbed and control marine locations in the Hunter Region, New South Wales, Australia. After this period, the oysters were retrieved and the gills dissected and extracted for analysis of the saponified lipid components (including fatty acids and sterols), using gas chromatography-mass spectrometry (gc-ms). Multivariate analysis (discriminant function) of the gc-ms lipid profiles indicated that the lipid homeostasis in oysters from the sewage locations was significantly different compared with that observed in oysters from control locations (p < 0.0001). The primary factor discriminating between sewage and control locations was the level of beta-sitosterol, a plant sterol derived from domestic sewage and marine algae. The results indicate that gill lipid metabolism differentially alters in response to deployment of oysters into either sewage-contaminated or control locations. This method of analysis provides a sensitive measure for the biological impact of composite waste cocktails on strategically located marker organisms in affected environments.
Aquatic insect communities and salmonid populations were sampled above and below a municipal sewage outfall on the East Gallatin River. Numbers of Trichoptera, Ephemeroptera, Coleoptera, and Plecoptera 0.45 mile (0.72 km) below the sewage outfall were lower than those found above. This reduction was associated with the occurrence of "sewage fungus" (Sphaerotilus sp.) on the bottom. An increase in the number of Diptera was associated with intra-ordinal changes in genera. Volumes of insects in each of these five orders declined, A partial recovery in the insect community was indicated at 3.85 miles (6.19 km) below the sewage outfall by an increase in numbers and volumes of all insects. At 12.65 miles (20.35 km) below the outfall, the number of aquatic insects was more than 13 times that found above. This was attributed to a return to carrying capacity and/or to the "fertilizing" effect of the sewage. Rainbow trout (Salmo gairdneri), brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), and mountain whitefish (Prosbpium williamsoni) were found above the sewage outfall but only rainbow trout were present after complete mixing of the sewage had occurred. Rainbow trout was the most numerous salmonid in the river. Above the outfall, the standing crop of rainbow trout was the same in summer and winter. Below the outfall, a marked drop in the standing crop occurred during winter. This was associated with an increase of free ammonia (N-NH3) in the river.
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