HR: 1330h
AN: NB33J-08    [Abstracts]
TI: Predation Risk versus Pesticide Exposure: Consequences of Fear and Loathing in the Life of Stream Shredders
AU: * Pestana, J T
EM: jpestana@bio.ua.pt
AF: Departamento de Biologia, Universidade de Aveiro, Campus Universit rio de Santiago, Aveiro, 3810-193 Portugal
AU: Baird, D J
EM: djbaird@unb.ca
AF: NWRI (Environment Canada) @ Canadian Rivers Institute, Department of Biology, University of New Brunswick, Canadian Rivers Institute, Department of Biology, University of New Brunswick 10 Bailey Drive P.O. Box 45111, Fredericton, E3B 6E1 Canada
AU: Soares, A M
EM: asoares@bio.ua.pt
AF: Departamento de Biologia, Universidade de Aveiro, Campus Universit rio de Santiago, Aveiro, 3810-193 Portugal
AB: Stream invertebrates are exposed to complex stressor regimes including both biotic and abiotic factors. Species living in streams in agricultural landscapes are often subjected to episodic or continuous exposures to low levels of agrochemicals, which may approach or exceed specific substance guidelines. Sublethal effects of pesticides may result in direct effects on organisms (e.g. reduced physiological performance), which may in turn contribute to indirect effects relating to survival (e.g. increased predation risk). Here, we investigate the possibility that predator-release kairomones can act additively with low-level pesticide exposure to reduce physiological performance and survival of stream invertebrates in previously unforeseen ways. Feeding, metabolic and behavioural responses of two shredder insects, the North American stonefly Pteronarcys comstockii and the European caddisfly Sericostoma vittatum were measured under exposure to the insecticide imidacloprid at different levels of indirect predation stress using predator-release kairomones from Brown Trout (Salmo trutta). Pteronarcys feeding was measured in terms of mass of naturally conditioned alder leaf discs consumed over a 6-day and 10 -day period in animals held in cages in stream mesocosms. Pteronarcys feeding was impaired at 1 ppb in the 6-day trial and at 0,5 ppb in the 10-day trial relatively to unexposed controls. Metabolic rate was measured in the lab in terms of oxygen consumption of Pteronarcys. Animals exposed to 0.5 and 1 ppb imidacloprid showed elevated respiratory rates compared to controls. Laboratory experiments with Sericostoma, currently in progress, are examining the separate and combined effects of imidacloprid and predator kairomone on similar endpoints. These preliminary results are discussed in relation to the development of the Mechanistic Unifying Stressor Effects (MUSE) model which can be used to predict combined ecological effects of multiple stressors at the population level.
DE: 9810 New fields (not classifiable under other headings)
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly