Dominance of invasive mollusks in the benthos of Lake Marion, a large impoundment in South Carolina, USA
Taylor, Barbara E.; Bulak, James S.; Morrison, John
published: Feb 1, 2016
ArtNo. ESP141018703004, Price: 29.00 €
The benthos in the main basin of Lake Marion, a 330-km2 impoundment on the Santee River in the Coastal Plain of South Carolina, was dominated by mollusks, including the Asiatic clam Corbicula sp. and the olive mystery snail Viviparus subpurpureus, and insects, including the burrowing mayfly Hexagenia limbata and dipterans. Corbicula sp. appeared in Lake Marion about forty years ago; V. subpurpureus, a native transplant from Gulf Coast drainages, about a dozen years ago. Benthic sediments were mainly silt; abundances of benthic invertebrates varied with water depth, but not with sediment attributes. Dry biomass, excluding shell, of benthic invertebrates ranged from 80–82 g m –2 in the upper main basin to 37 g m –2 in the middle main basin and 12 g m –2 in the lower main basin. Corbicula sp. contributed 60–80% of the total biomass; insects, < 10%. Mollusks do not appear to be heavily consumed by pelagic fish in Lake Marion. To the extent that the mollusks sequester resources that might otherwise support prey such as benthic insects or zooplankton, they may effectively reduce productivity of the fisheries. However, excess consumption of pelagic resources by the mollusks, particularly Corbicula sp., may subsidize other benthic consumers such as H. limbata, and nutrients released from digested pelagic material may promote benthic algal production.