Effect of Beach Nourishment on Salmonid Prey Resources of Lincoln Park Beach, Seattle, Washington: Pre-project Conditions

摘要

The Seattle District of the U.S. Army Corps of Enginners is planning to conduct beach nourishment at Licoln Park in west Seattle in the summer of 1998. This consists of placing up to five feet of gravelly fill in about three acres of the high intertidal zone of the beach, that is, the area between five and twelve feet above mean lower low water. Beach nourishment is expected to protect the existing seawall and park facilities from erosion for five to ten years. The Corps has described the timing, composition, and extent of filling in their Final Environmental assessment (U.S. Army Corps of Engineers 1986). The primary federal resource issue is the project's effect on the salmon that use the area, since restoring Pacific salmon and steelhead is one of the Fish and Wildlife Service's principal goals. Our agency expressed this concern in the Fish and Wildlife Coordination Report (Cooper 1986). We explained that juvenile salmon migrating seaward from their rivers of origin during the spring and early summer feed in the nearshore areas of Puget Sound. Much of the nearshore preu for some species of salmon comes from epibenthic zooplankton, which i the assemblage of crustacea produced on the surface of the bottom or within several centimeter above it. The specific issue is whether placement of the fill will change the stability and texture of the bottom in a way that reduces the density of those types of epibenthic zooplankton upon which juvenile salmon are know to feed.