Long-term Changes Of Main Ecological Factors Of The Jiaozhou Bay Ecosystem

Jiaozhou Bay receives great impact from human activities,and sustainable development of the bay ecosystem has become a major concern of both scientists and the local government. Thus,a systematic investigation of the ecological factors and analysis of the data is obviously necessary for a better understanding of the ecosystem and subsequent measures.Based on the diverse ecological data series collected by the Jiaozhou Bay Ecosystem Research Station (JERS) of the Chinese Ecosystem Research Network (CERN) for the last decades,a multi-functioned data base,the "JIAOZHOU BAY ECO-DATABASE",was constructed with MapBasic under GIS software Mapinfo4.0. which provides accesses to the data files by "select","query","draw",and "organize" as well powerful analytical tools including statistics and time series analysis.Using the above data base,the author looked into the long-term changes in nutrients,phytoplankton,and examined the impact of socio-economical factors in the surrounding area on the bay. The following are the major outputs of this study.1. COD increased dramatically in last decade,surface water COD increased 44.7% from 1991 to 1998.2. NO-2-N,NOVN and NH+4-N concentrations had been continuously rising since 1960's,and increased 4.64,2.79 and 3.32 fold from 1960's to 1990's respectively.3. PO P concentration reached the top of 13. 22 L in 1980's and then decreased slightly.4. SiO Si concentration,so far,had dropped off 63.6% since 1980's.5. the factor most probably limiting phytoplankton growth had been changed from N to Si.6. the biodiversity of phytoplankton had risen slightly since 1990's,but the biodiversity of zooplankton,as a key link in the food chain,had been falling in the same time.In conclusion,great changes in ecological conditions of the Jiaozhou Bay have taken place in the past decades,which may cause significant changes in the ecosystem level and consequently affect the sustainable development of the bay. Cautions should be used for the future management of the greater Jiaozhou Bay ecosystem including humen activities in its adjacent surroundings in the future.