Characteristics of Trophic States and Phytoplankton Response

Studies on phytoplankton and nutrient dynamics related to trophic conditions was carried out in coastal ecosystem through analyses on long-term data from freshwater reservoirs and field study as well as ecosystem dynamical modeling analysis. Long-term data analysis of water quality and phytoplankton response in a reservoir systems were performed to investigate variations of nutrient inputs from watershed into freshwater reservoirs and later to coastal water systems. The eutrophication of freshwater in reservoirs can influence the trophic state of the coast since freshwater is introduced into the coastal estuary especially during wet season. The nutrient loading from freshwater, phytoplankton, trophic state by trophic index (TRIX) and turbid condition by turbidity index (TRBIX) was investigated. An ecosystem model was developed for size-structured phytoplankton dynamics of coastal estuary to investigate the response of phytoplankton to environmental changes expected. Simulation results showed the general feature of phytoplankton dynamics related to abiotic and biotic mechanisms in the coastal estuary. The results may contribute to a better understanding for the behavior of ecosystem