Habitat Development Field Investigations, Windmill Point Marsh Development Site, James River, Virginia. Appendix C. Environmental Impacts of Marsh Development with Dredged Material: Acute Impacts on the Macrobenthic Community.

摘要

Macrobenthos was sampled in a tidal freshwater portion of the James River, Va., near Windmill Point, in the area of construction of a wetlands habitat from dredged materials -- the development being directed by the Army Engineer Waterways Experiment Station. The benthic communities in the area of the habitat development site were dominated by the bivalve Corbicula manilensis; the oligochaetes Limnodrilus spp. and Ilyodrilus templetoni; and larvae of the insects Coelotanypus scapularis and Hexagenia mingo. The dominant organisms are generally eurytopic with respect to sediments; many had higher densities in muddy sediments, although Corbicula preferred sand. Most of the important species were highly opportunistic and thus the community was able to recover quickly from perturbations. This characteristic minimized the effects of habitat development. Acute impacts were detected at the habitat site where organisms were buried by construction and at the excavation where organisms were removed along with the sand and gravel used in construction of the dike. Long-term changes associated with the habitat were limited to areas of gross sediment alteration, such as at the excavation and dike perimeter. No other broad-scale effects, acute or long term, could be detected that were attributable to the habitat construction. More extensive acute effects due to sedimentation may have occurred but, because of its resilience, the community was able to recover in the 6 months that lapsed before postconstruction sampling.