HR: 08:30h
AN: NB51A-01    [Abstracts]
TI: Effects of Agricultural Pollutants on Competition Between Filter-Feeding Caddis Flies
AU: * Olsen, D A
EM: dean.olsen@uvm.edu
AF: Rubenstein Ecosystem Science Laboratory, University of Vermont, 3 College Street, Burlington, VT 05401 United States
AU: Watzin, M C
EM: mary.watzin@uvm.edu
AF: Rubenstein Ecosystem Science Laboratory, University of Vermont, 3 College Street, Burlington, VT 05401 United States
AB: The effects of agricultural pollutants on competition between lotic macroinvertebrates are largely unstudied. We investigated how agricultural pollution affects competition between larvae of two caddis flies, Hydropsyche spp. and Brachycentrus appalachia. Month-long laboratory experiments were conducted in recirculating stream microcosms at two levels of Hydropsyche abundance: low density (80 Hydropsyche and 40 Brachycentrus per tank) and high density (300 Hydropsyche and 40 Brachycentrus). Experimental factors tested were agricultural pollutant addition (cow manure compost and sand) versus control tanks and taxon combination (Hydropsyche only, Brachycentrus only, and both taxa). In high-density experiments, mortality and drift of Hydropsyche were higher in agricultural tanks than in controls and more Brachycentrus drifted in tanks with Hydropsyche present. In low-density experiments, mortality of Brachycentrus was higher in tanks with Hydropsyche present. In both high and low-density experiments,Brachycentrus had lower mean condition (as measured by body-length residuals) in the presence ofHydropsyche, although these differences were only statistically significant in the high-density experiment. No difference in condition was observed for Hydropsyche at either density. Our results provide evidence of both competition between Hydropsyche and Brachycentrus and direct effects of pollutant addition, but the pollution effects did not alter the competitive interactions between the two species.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly