The Influence Of Coastal Upwelling On The Distruibution Of Plankton In Zhejing Province

Based on the data collected in Yushan Fishery inshore waters in April,July andNovember of2010,the relationship between horizontal distribution, seasonal changesof phytoplankton and upwelling were discussed in this paper using qualitative andquantitative method.The results revealed that there were a total of81species of phytoplankton, including35species of red tide algae in the estuary. There were apparent seasonal variations innumbers of species, horizontal distribution and dominant species due tocomprehensive influences of Jiaojiang runoff, Zhejiang coastal upwelling and Taiwanwarm current. The primary dominant red tide algae were Chaetoceros curvisetus,Skeletonema costatum, Melosira sulcata and Coscinodiscus jonesianus. summer is themost pronounced upwelling season and the region located in southeast waters ofdachen island. Horizontal distribution of phytoplankton had a obvious seasonalvariation.phytoplankton abundance peaked in summer (438.02×105cell/m3), and itwas the second highest in autumn (147.17×103cell/m3), the lowest in spring(67.69×103cell/m3).summer, the region with high abundance value situated in the eastwaters of dachen island,was contrast to spring and autumn which in the west. Thisvariation was affected, to some extent, by the intensity of upwelling. Summer was themost apparently upwelling season and it was found that the region affected byupwelling showed a basic correlation with that of high phytoplankton abundance.Jiaojiang runoff and Zhejiang coastal current play an important role in phytoplanktonabundance as a result of the relevantly weak upwelling in spring and autumn. Obviousvariation of the three seasonal dominant species in investigated waters can beobserved, Melosira sulcata in spring, Chaetoceros curvisetus in summer andSkeletonema costatum in autumn are the main species that result in the seasonalchange of phytoplankton abundance.The result showed that a total of64species mainly dominated by copepods wereidentified, which comprised coastal temperate warm water species, offshore temperatewarm water species, coastal subtropical water species, offshore subtropical waterspecies and oceanic tropical water species altogether five ecological group. Coastaltemperate warm water species were prevalent in spring, coastal subtropical waterspecies and offshore subtropical water species in summer and subtropical species inautumn when it came to species composition. The phenomenon that quantity oftemperate warm water species in summer higher than that in spring and autumn,primarily caused by the upwelling brought the temperate warm water species from bottom to surface, is different from that in East and Yellow China Sea. Additionally,coastal species is the dominant group which means that coastal current is the foremostwater mass that influence this seas. The tendency of abundance composition, in whichcoastal temperate warm water species account for98.79%in April and also aremarkable part in July, coastal subtropical water species occupied the highestproportion in October, coincided with that species composition. Upwelling leadedtemperate warm water species appeared in large numbers is a key factor that affectedthe ecological composition in this waters. The coastal species became the dominantgroup, which influenced by Jiao-jiang runoff, was a prime ecological character ofzooplankton in this seas.