Meeting Abstract
P3-70 - Can physiological traits of aquatic insects provide clues about their sensitivities to changing salinity regimes? Cochran, JK*; Orr, SE; Buchwalter, DB; North Carolina State University; North Carolina State University; North Carolina State University jkcochra@ncsu.edu
Concerns are rising about biodiversity losses associated with both the increasing concentrations of major ions in certain areas and decreasing concentrations elsewhere. Ecological monitoring programs suggest that salinity plays a role in determining where aquatic species can thrive. Generalist species occur over a wide range of salinities while specialist species appear to have more narrow ranges of salinity tolerance. We do not understand what factors determine these salinity niches nor what determines how species differentially respond to salinity changes in nature. We hypothesize that apparent salinity niches could be explained by physiological traits that vary among species, including the efficiency of ionic uptake rates under very dilute conditions and the limitation of excessive ion uptake when waters are more ion rich. We used radiotracers (22Na, 35SO4 and 45Ca) to compare ion uptake rates in mayflies (Neocloeon triangulifer, Isonychia sp., Maccaffertium modestum, Drunella coloradensis), caddisflies (Hydropsyche betteni), and mosquitoes (Aedes albopictus). We also assessed cuticular permeability by measuring whole-body salt composition (via ICP-MS) and loss of previously acquired 22Na (after 9 hours of deionized water challenge) in these same taxa. While these studies are ongoing, clear physiological differences in transport dynamics are emerging among species (e.g., 19-fold difference in Ca uptake rate across 5 taxa in control water) and permeability (e.g., N. triangulifer lost 29% of its 22Na label after 9 hour deionized water challenge while H. betteni lost only 11%). This work highlights the unique osmoregulation strategies evolved by different aquatic insect taxa and how these physiological differences contribute to major ion toxicity in a changing world.