HR: 1330h
AN: NB33J-07    [Abstracts]
TI: Effects of Insecticides on Benthic Communities Under Pulse and Press Exposures.
AU: * Heard, K
EM: kheard@unb.ca
AF: Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Culp, J M
EM: Joseph.Culp@ec.gc.ca
AF: Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Culp, J M
EM: Joseph.Culp@ec.gc.ca
AF: National Water Research Institute, Environment Canada, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Luiker, E
EM: Eric.Luiker@ec.gc.ca
AF: National Water Research Institute, Environment Canada, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Alexander, A
EM: Alexa.Alexander@unb.ca
AF: Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Baird, D J
EM: Donald.Baird@ec.gc.ca
AF: Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Baird, D J
EM: Donald.Baird@ec.gc.ca
AF: National Water Research Institute, Environment Canada, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AU: Curry, R A
EM: racurry@unb.ca
AF: Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB E3B 6E1 Canada
AB: Benthic macroinvertebrates are often exposed to short-term pulses of pesticides following runoff events as well as through low background exposure. Pulse events may be important exposure routes for highly soluble insecticides such as imidacloprid. We examined the effects of imidacloprid on the benthos through press and pulse exposures, beginning with a press, range-finding field experiment (0, 5, 15 ppb) designed to estimate thresholds for effects on the invertebrate community. This experiment demonstrated a dose response with higher insecticide treatments reducing abundance, richness and evenness relative to the control. A subsequent experiment aimed at lower concentrations, more consistent with natural levels, contained both pulse (0, 0.1, 0.5, 1.0, 5, 10 ppb) and press (0, 0.1, 0.5, 1.0 ppb) concentrations to detect which exposure caused effects in the benthic community, or affected emerging insect abundance and size. No significant differences in abundance or richness were found with concentrations up to 1 ppb regardless of treatment or design. However, sublethal effects were observed as Baetis adults were generally longer (total length) in pulse versus press exposures and had larger abdomens at higher insecticide concentrations. Current studies are measuring insecticide concentrations during the flood hydrograph to better understand the consequences of these sublethal effects.
DE: 1803 Anthropogenic effects
DE: 1860 Runoff and streamflow
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly