Assessment of Spatial and Temporal Variability in Ecosystem Attributes of the St Marks National Wildlife Refuge, Apalachee Bay, Florida

Six carbon-flow networks of a seagrass ecosystem were constructed from comprehensive databases collected at three different sites during January and February 1994, respectively. The flow models, which consisted of 51 compartments each, were analysed by means of network analysis and the resultant outputs compared on spatial and temporal scales. Results on the biomass, species diversity, input, rates of exchange and export of material showed distinct differences between the sites in a month, as well as between months at the same site. System-level attributes, such as total system throughput, ascendancy, the structure and magnitude of recycling, flow diversity, etc., derived from network analysis, also showed noticeable differences from site to site and between months. There was an increase in ecosystem activity and in the magnitude of its global properties between months which are ascribed to a rise in temperature between months, increased rates in respiration and growth of resident species populations, as well as to the immigration of large numbers of fish and birds