Student Research Projects

Role of Semiaquatic Turtles in Lake Nutrient Cycles

Student Katherine Burchett
Faculty Mentor(s)
Department Biology


Consumers such as fish and zooplankton have been shown to contribute substantially to aquatic nutrient cycles (Vanni 2002, Ann. Rev. Ecol. Syst.). Despite the abundance of freshwater turtles, our substantial review of the scientific literature indicates that no investigators have quantified the degree to which turtles contribute to lake nutrient cycles. Our research will seek to a) conduct a mesocosm study manipulating the density of 2 common taxa of semiaquatic turtles, Chrysemys picta picta and Trachemys scripta elegans, and b)quantify nutrient release rates of these 2 taxa. The nutrient release measurements will be conducted similar to published studies of nutrient release by fish (i.e., Schaus et al. 1997, Limnol. Oceanogr.), except of longer duration to more effectively document the sporadic excretion by turtles (vs. continuous excretion by fish). Mesocosm studies will use fifteen blue polyethylene tanks (440L volume – Aquatic EcoSystems, Inc.) filled with lake water and sediments from Lake Taylor, on the VWC campus. Tanks will randomly be assigned to one of 3 treatments: control (no turtles added), C. picta added, or T. scripta added, with five replicates for each treatment. Phytoplankton dynamics will be assessed by measuring chlorophyll a abundance and nutrient dynamics (soluble, total and particulate N) will be measured on water samples collected twice each week. Zooplankton will be sampled weekly during the 4 week experiment


2008 VFIC Claude Moore Charitable Foundation Fellowship


Association of Southeastern Biologists, Birmingham, AL, April '09