Meeting Abstract

12.1  Wednesday, Jan. 4  Divalent metal trafficking in aquatic insects: A comparative approach POTEAT, MD*; BUCHWALTER, DB; North Carolina State University, Raleigh mdpoteat@ncsu.edu

In streams and rivers, aquatic insects typically comprise 80-95% of the invertebrate species pool and are ecologically integral. With ~7,000 aquatic insect species described to date in North America, this diversity is daunting from an experimentalist’s perspective but provides a unique opportunity to explore the degree to which fundamental physiological processes vary with phylogeny. In North America alone, the family Hydropsychidae (Order: Trichoptera) currently contains 157 recognized species and the family Ephemerellidae (Order: Ephemeroptera) contains 75 species. We are in the process of comparing metal fluxes (109-Cd, 65-Zn and 45-Ca) and related physiology in selected species from these 2 families. Experiments with Hydropsyche sparna provide several lines of evidence that Cd and Zn utilize a high capacity Ca transport system, but with much greater affinity than Ca to that system. All three metals respond similarly to Ca channel blockers nifedipine and verapamil (no effect) and the Ca-ATPase inhibitor ruthenium red (dramatic suppression of influx). Across species, uptake rate constants for Cd varied 3-fold among 3 hydropsychids and 29-fold among 8 ephemerellids. Uptake rate constants of Cd and Zn strongly co-varied among all 11 species (r=0.948, p<0.0001), providing additional evidence for a shared transport systems for each metal. Efflux rate constants also strongly co-varied across 10 species (r=0.946, p<0.0001). As more species are added to this dataset, we will develop a sense for how much physiological variability in metal transport occurs within each of these diverse families and the extent to which this variability can be attributed to phylogeny. Ultimately we ask if phylogenetic position can possibly predict physiological performance in these widely used ecological indicators.