Short-term lethality and sediment avoidance assays with endrin-contaminated sediment and two oligochaetes from Lake Michigan

Mean 96-hr LC 50 values and standard deviations for the oligochaetes S. heringianus and L. hoffmeisteri exposed to endrin-contaminated sediment were 2,588±1,974 μg/g dry weight sediment for 4 assays and 2,725±955 μg/g for 2 assays, respectively. Mixed species testing data suggested that the toxicity to L. hoffmeisteri was reduced in the presence of S. heringianus , yet further testing is required. Ninety-six hour EC 50 burrowing avoidance values for both species (19 and 15.3 μg/g for S. heringianus and 59 μg/g for L. hoffmeisteri ) were approximately 46 and 150 times lower than their respective mean 96-hr LC 50 values. Both S. heringianus and L. hoffmeisteri initially burrowed in contaminated sediment and then returned to the surface in numbers somewhat proportional to the sediment concentration and the length of exposure. Future use of oligochaete behavioral responses to subiethal sediment contamination for pollutant impact on benthic communities is promising.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48067/1/244_2005_Article_BF01055159.pd

Assessment of the Effects of the Pesticide Imidacloprid on the Behaviour of the Aquatic Oligochaete Lumbriculus variegatus

Contaminants, such as pesticides, can cause direct toxic effects when released into aquatic environments. Suitably sensitive species can help us understand and predict the impacts of such pollutants. Automated sediment toxicity testing and biomonitoring has grown rapidly, and biomonitoring instruments have proven appropriate for studying the effects of pollutants. A new approach in online biomonitoring, using the multispecies freshwater biomonitor was developed in the present study, using whole-sediment toxicity tests and behavioural responses of the freshwater oligochaete Lumbriculus variegatus. Endpoints, such as mortality and growth, were used to study the effects of the pesticide imidacloprid and to achieve a gradient of responses; exposures to contaminated sediments were performed over 10 days' duration (short-term tests). High mortality was observed in the three highest concentrations of imidacloprid, and inhibition of behaviour was monitored along a gradient of pesticide concentration. Exposure to imidacloprid-contaminated sediments affected growth, behaviour, and avoidance in L. variegatus