Sundareshwar, P. V. University of South Carolina, pvs@biol.sc.edu
Morris, J. T. University of South Carolina, morris@biol.sc.edu

 
DIFFERENTIAL NUTRIENT LIMITATION AMONG TROPHIC GROUPS IN A PRISTINE SALT MARSH ESTUARY, SOUTH CAROLINA, USA
 
Nutrient limitation is a function of relative nutrient solubility. Human influences on estuarine ecosystems affect ecosystem functioning by altering the relative availability of important nutrients such as nitrogen and phosphorus. We present here the initial response of dominant macrophyte (Spartina alterniflora) and microbes to fertilization in a salt marsh located in the pristine North Inlet estuary in South Carolina, USA. Nitrogen and phosphorus additions were carried out in a 4 (treatments) x 3 (replicates) factorial design. Each block consisted of a nitrogen, a phosphorus, a nitrogen + phosphorus and a control plot. Pore water nutrients such as ammonium, phosphorus, soluble sulfides and chlorinity were measured monthly. We used aboveground biomass and sediment pore water phosphatase activity as bioassays for plant and microbial response respectively. Conventional opinion suggests that saltmarshes are nitrogen limited. However, our results indicate that, at North Inlet, while plants are limited by nitrogen, microbes may be limited by availability of phosphorus. The release of phosphorus limitation of microbes may impact nitrogen cycling in this salt marsh by altering the rate of nitrogen fixation. This has important theoretical and practical implications and raises the possibility that marsh fertility is strongly governed by phosphorus availability and proximally by nitrogen.
 
Day: Tuesday, Feb. 2
Time:
Location: Sweeney Center
 
Code: SS49TU1201S