HR: 1330h
AN: B33E-10    [Abstracts]
TI: How Far is Far Enough? Invertebrate Responses to Physical Constraints on Drift Distance
AU: * Hoover, T M
EM: thoover@civil.ubc.ca
AF: Dept. of Civil Engineering, 2324 Main Mall University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: * Hoover, T M
EM: thoover@civil.ubc.ca
AF: Dept. of Forest Sciences, 3041-2424 Main Mall University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: Yonemitsu, N
EM: noboru@civil.ubc.ca
AF: Dept. of Civil Engineering, 2324 Main Mall University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: Richardson, J S
EM: john.richardson@ubc.ca
AF: Dept. of Forest Sciences, 3041-2424 Main Mall University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AB: Many stream insects enter the drift and disperse downstream. Once entrained, however, the probability of settling in a patch of suitable habitat is a function of the physical properties and behavior of the drifting insect, as well as the hydrodynamic characteristics of the habitat through which the insect is drifting. The roles that taxa-specific morphology and behavior play in determining drift distance were examined for four mayflies with different habitat requirements; two rheophilous taxa (Baetis and Epeorus) and two pool-dwelling taxa (Ameletus and Paraleptophlebia). Larvae were released in an experimental channel in low and high water velocities. The total distances traveled by live mayfly larvae (+ behavior, + morphology) were compared to heat-killed larvae (- behavior, + morphology), and a series of low-density tracer particles (- behavior, - morphology). Live Baetis and Epeorus drifted similar distances, whereas the drift distances of the two pool taxa differed substantially (Ameletus < Epeorus, Baetis < Paraleptophlebia). The settlement distributions of dead larvae and passive tracer particles show that settlement behaviors allow drifting larvae to avoid becoming entrained in large-scale turbulent flow structures. These results suggest that stream insects have evolved strategies that facilitate dispersal between patches of suitable habitat.
DE: 0400 Biogeosciences
DE: 3379 Turbulence
DE: 9901 NABS Student Award - Basic Research
DE: 9903 NABS Student Award Methodology
SC: Biogeosciences [B]
MN: 2005 Joint Assembly