() Field testing of a post-exposure feeding bioassay using Lumbriculus variegatus to assess sediment toxicity in-situ.
Williams, P1, Baird, D2, Culp, J2, Wrona, F3, 1 University of Stirling, Stirling, Scotland,U.K2 National Water Research Institute and University of New Brunswick, Fredericton, New Brunswick, Canada3 National Hydrology Research Centre (Environment Canada), Saskatoon, Saskatchewan, Canada
ABSTRACT- Previously a bioassay using post-exposure feeding rate of Lumbriculus variegatus was developed in the laboratory with a view to application in the field. Laboratory results suggested the bioassay could potentially be used in the field (in situ) at a variety of known or suspected contaminated and reference sites. Results from field trials demonstrated the bioassay methodology was practical and reliable for use. Holding chambers were simple to deploy and allowed for a realistic exposure scenario to sediments. Survival and recovery of animals from chambers after a five-day exposure was always greater than 90%, thereby allowing consistent measurement of post exposure feeding rate. A depression in post exposure feeding rate was detected at a number of sites where survival was not significantly affected, suggesting that the bioassay provides an ecologically-relevant and sub-lethal endpoint for in situ assessment of sediments. Along with the results of field trials practical considerations for the use of such techniques are discussed.
Key words: bioassay, Lumbriculus variegatus, in situ, sediment