Spatial and temporal variation in feeding preferences of top predatory fishes in a contaminated wetland ecosystem (Louisiana).

摘要

The Bayou LaBranche wetland system, located 22 miles west of New Orleans, LA, received wastewaters from Norco oil refinery from 1920 to 1995. In 1989, the sediment of one of the waterways, Bayou Trepagnier, was designated contaminated with Pb, Cr, Zn, and polycyclic aromatic hydrocarbons. In 1995, the wastewaters were diverted to the Mississippi River, taking with them the main source of fresh water for the system. After seven years of diversion, it is unclear whether contaminants or a loss of significant freshwater input has been more harmful to organisms in this system, or if the organisms have been impacted at all. The stomach contents of two top predators, spotted gar and largemouth bass, were analyzed to determine if there are seasonal variations in dietary preferences and if these variations are due to contaminants in the water and sediment or changes in water quality. The results indicate that the fish collected in Bayou Trepagnier are eating better and are in better condition than those in the other two waterways.