1. Aquatic Insect Osmoregulation – National Science Foundation
The maintenance of appropriate concentrations of major ions (e.g. Ca, Na) is fundamental to the performance of all aquatic organisms. Insects thrive in dilute waters, but are extremely rare in saline waters and do not perform well when concentrations of major ions become elevated in previously dilute ecosystems. Research in this area includes the measurement of ionic flux rates using radiotacers, the measurement of gene expression using RT-qPCR for various ion transporters, proteomics of gill tissues, and bioassay approaches. We collaborate with Dr. Chuck Hawkins at Utah State University to better ubderstand how the ionoregulatory traits of different aquatic insect species relate to their distributions in nature across gradiants of major ions.
Sarah Orr is leading efforts to understand salinity temperature interactions and acclimation in our lab-reared mayfly N. triangulifer.
Jamie Cochran is leading efforts to understand differences among field collected aquatic insects in ion transport under various major ion conditions.
2. The bioaccumulation and trophic transfer of perfluoroalkyl substances (PFAS). National Institites of Environmental Health Sciences -Superfund Program
PFAS in aquatic ecosystems has emerged as a major issue locally here in NC and internationally. We are examining the relative importance of direct aqueous uptake and trophic transfer of PFAS in preiphytion, aquatic insects, and zebrafish. We are specifically interested in generating an understanding f how PFAS structures relate to their bioaccumulation potential via ecologically relevant exposure routes.
Anna Boatman is leading this project and is stepping up our diatom culture capabilities.
1. Thermal physiology
Our work in this area is focused on understanding the physiological basis for ecologically-relevant thermal limits in aquatic insects. We are interested in explicitly linking physiological processes to life history outcomes in lab-reared mayflies, and in linking physiological measurements to results of ecological niche modeling. Former Post Doc Hsuan Chou lad our offorts on this front.
Jamie Cochran got us going with respirometry studies in N. triangulifer as an undergraduate student and we continue to learn new things.
3. Development of the mayfly Centroptilum triangulifer as a laboratory model
Most freshwater insects are very difficult to rear. As a result, laboratory scientists have shied away from working with them and have instead focused on crustaceans (e.g. daphnids) and fish (e.g. zebrafish). This has had a disconnecting effect in the water pollution world, because the species used to develop environmental standards via toxicity testing are different from the species that dominate real freshwater ecosystems (insects). Fortunately, Bern Sweeney and David Funk (Stroud Center) have excelled at developing culture methods for C. triangulifer (and other species) and have shared his expertise with us and a handful of other labs. Our lab has worked with Stroud to conduct life cycle based assays and we have developed RT-PCR probes for suites of genes related to thermal and ionoregulatory physiology.
4. Trace element bioaccumulation and trophic transfer
This area of research has been a mainstay of the lab. We use isotopes to measure the flux rates of trace elements (e.g. Cd, Zn, Se, Hg, Mn) into aquatic organisms either directly from water or through dietary pathways. We also explore how species vary in their abilities to eliminate and detoxify the metals they have accumulated via these exposure pathways. Current work is focused on arsenic at the base of aquatic food webs with support from WRRI.
5. Comparative and Evolutionary Physiology
Because insects are so species rich, we can only work with a relatively small number of species relative to their diversity in nature. The evolutionary history of these organisms as secondarily aquatic (derived from numerous invasions of freshwater ecosystems by terrestrial ancestors) gives us the opportunity to see how this history manifests in different physiologies within and among different insect lineages. We use comparative approaches and phylogenetically based statistical approaches to explore physiological patterns across species.