Meeting Abstract
Lipophilic insecticides and fungicides are carried in runoff from sites of application to aquatic environments where they come into contact with non-target invertebrates like zooplankton. Unfortunately, few studies assess the impact of these chemicals on early zooplankton development, and almost nothing is known about the effect of exposures during or immediately following periods of obligate dormancy. Because the life-cycles of most inland and estuarine zooplankton involve a dormant stage, it is important that management authorities understand the effect of anthropogenic chemicals on those life-stages. We used post-diapause cysts of the brine shrimp, Artemia franciscana, as a zooplankton model with which to test the effect of the common agricultural fungicide, fenarimol, and insecticide tebufenozide. Brine shrimp cysts were dechorionated and preincubated with fenarimol or tebufenozide for 24 h on ice prior to hatching at room temperature in the continued presence of the chemical. Tebufenozide had no effect on development, emergence from the first embryonic cuticle, or hatching of the nauplius larva. However, exposure to 1ug/ml fenarimol significantly slowed development, and delayed both emergence and hatching. Development was also delayed by preincubation with 1ug/ml fenarimol even if the embryos were subsequently washed and allowed to develop in a fenarimol free medium. This indicates that the embryonic cuticle of A. franciscana is permeable to the fungicide. It is important to note that an ecologically relevant concentration of fenarimol had no effect, and that this model is limited to assessing susceptibility when an embryonic cuticle is the only permeability barrier present.
