Watersheds Nutrient Loss and Eutrophication of the Marine Recipients: A Case Study of the Jiaozhou Bay,China

Industrialization and urbanization along the coastal population centers have brought great changes in the land cover and material fluxes from watersheds to receiving bays and estuaries. We have embarked a multiyear research project on “Watersheds Nutrient Loss and Eutrophication of Jiaozhou Bay” for the period of 2000 to 2004, funded by the Natural Science Foundation of China to examine human influence on the marine sector of ecosystem. Jiaozhou Bay, located in the southern part of Shandong Peninsula, was selected because of the existence of long-term hydrographic and meteorological records since the 1930s and recent observations on the marine ecological variables. We have made extensive and periodic measurements on the water movement, nutrients, phytoplankton, and microbe in water column and bottom sediments. Box and 3-dimensional hydrodynamic models were developed and utilized to understand the evolution of eutrophic status with time. It was found that primary productivity has suffered from silica depletion followed by phosphate, and the dominance of large phytoplankton has been replaced by small-size communities. These ecosystem changes were brought by the changes in the relative contribution among major pathways and concentrations, owing to the human activities in the watershed. Eight articles in this volume reported various aspects of the linkage between watershed human activities and ecosystem for the Jiaozhou Bay as the initial outcome of this project.