We assessed the influence of ice-storm-derived debris dams on aquatic macroinvertebrates and stream substrates in a high-gradient
watershed in the eastern Adirondack Mountains of New York State. Using a modification of electrofishing techniques, invertebrates
were collected once before (June 2000) and once after (June 2001) wood removal from the downstream reach in each of six pairs
of reaches (second and third-order streams). Stream substrates were also mapped in 2000 and 2001 to evaluate shifts in dominant
substrates within a reach following wood removal. The following metrics were used to compare the invertebrate communities
before and after wood removal: genera similarity, Shannon–Weiner equitability, taxa richness, dominant taxon, percent dominance
and functional feeding group relative abundance. The changes in removal reaches were evaluated relative to changes in upstream
reference reaches using a Before-After Control-Impact (BACI) design and analysis. Stream substrates did not change significantly
in response to wood removal, although a trend toward coarser substrates was observed following removal. Following wood removal,
the relative proportion of grazers increased upstream and downstream from removed dams in all streams; however, comparisons
of other metrics indicated no significant response to removal. Invertebrate responses to wood removal were lower than expected,
perhaps due to the presence of abundant boulder-formed pools in this high gradient system.
Keywords Adirondack Mountains - macroinvertebrate - ice storm - debris dam - high gradient stream - BACI