Meeting Abstract

P3-5   -   Effects of food supply and water flow on bioturbation by coastal invertebrates Frey, MR*; Dorgan, KM; Dauphin Island Sea Lab, Dauphin Island, AL; Dauphin Island Sea Lab, University of South Alabama, Mobile, AL mfrey@disl.org

Sediment mixing by marine invertebrates (bioturbation) modifies geochemical and geotechnical properties of sediments and can facilitate the presence of other organisms. Many infaunal organisms are deposit feeders whose ingestion and egestion of sediments contribute strongly to bioturbation. Food availability can alter animal behavior and overall activity, and the addition of food has been shown to increase bioturbation rates, although these effects differ between species. In addition to food resources, water flow may significantly alter feeding behaviors, especially for infaunal invertebrates that are able to switch between deposit and suspension feeding. We manipulate water flow and food supply in a laboratory experiment to test whether different modes of food delivery impact behaviors and bioturbation rates by these interface feeders (e.g., brittle stars, oweniid polychaetes). Algae labeled with 13C is added under flow and no-flow conditions, and luminescent tracers and isotopic analysis are used to measure mixing. We hypothesize that food deposition (no flow) will induce greater bioturbation than the addition of suspended food (flow) because the animals will need to actively forage in the sediment. The addition of food in either case should cause an increase in sediment mixing. Environmental effects on the feeding behaviors of infauna may be important to consider alongside functional groups when evaluating the bioturbation potential of coastal sediment communities.