PARENT SESSION
Poster Session #23: Fish, Lakes, Streams, and Wetlands.
Wednesday, August 8, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
63
Fish response to debris dam removal in ice storm-impacted streams of the Adirondack Mountains (NY, U.S.A.).
Warren, Dana1, Kraft, Clifford1, 1
ABSTRACT- In 1998, a severe ice storm damaged the forest canopy and increased the number of woody debris dams in eastern New York streams. In many stream systems, debris dams dissipate energy and provide habitat for fish and invertebrates. This research investigates the role of debris dams in small, high gradient streams of the northeastern United States. Fish abundance, invertebrate community composition and stream geomorphology were assessed during summer 2000 in two first-order, two second-order and one third-order stream within the same drainage basin. Study reaches were established with equal numbers of habitat units both upstream and downstream from prominent debris dams, and reaches were paired based on similar debris dam function. In August 2000, all woody debris less than 30-cm diameter was removed from the downstream reach of each pair. Debris removal had a pronounced effect in second-order streams, where brook trout (Salvelinus fontinalis) populations - one of two fish species present -- dropped significantly in removal reaches by comparison with reference reaches (p<0.05). In third-order study reaches, trout abundance did not change following dam removal, and in first-order reaches, trout response to debris removal was mixed. Although generally considered important fish habitat, debris dams may have a limited habitat function for fish in streams with high habitat heterogeneity, such as those where boulders are dominant pool-forming elements.
KEY WORDS: woody debris, Salvelinus fontinalis, ice storm, debris dam function