HR: 14:30h
AN: B43B-05    [Abstracts]
TI: Influence of wood and forests on fish abundance and richness in a large floodplain river
AU: * Gregory, S
EM: Stanley.Gregory@oregonstate.edu
AF: Oregon State University, 104 Nash Hall, OSU, Corvallis, OR 97331 United States
AU: Wildman, R C
EM: Randall.Wildman@oregonstate.edu
AF: Oregon State University, 104 Nash Hall, OSU, Corvallis, OR 97331 United States
AB: We investigated the influence of large wood and adjacent floodplain forests on fish assemblages along the 230-km mainstem of the Willamette River, Oregon. Fish were sampled in open reaches using boat electroshocking, beach seining, and backpack electroshocking in paired sites with intact forest and land converted to agriculture or urban use. Fish abundance and richness were statistically significantly greater in reaches with intact forest. We observed that wood abundance in the river was related to density of trees along the floodplain margin and developed an intensive sampling approach for determining fish abundance and richness in accumulations of large wood in the river. Fish were sampled from "wood corrals" and marked by fin clipping. These sites were sampled the following day to determine the abundances of each species by mark-recapture. Nets were placed around similar areas in adjacent habitats without wood. Fish numbers around wood accumulations were more than double those in areas without wood. The number of fish species was greater by an average of four species in sites with wood. These results were used to project the consequence of historical changes in fish abundance and richness in the Willamette River and forecast possible responses to future land use change.
UR: http://willametteexplorer.info
DE: 1821 Floods
DE: 1848 Networks
SC: Biogeosciences [B]
MN: 2005 Joint Assembly