Study On Phytoplankton Community Structure And The Relationship With Feeding Habits Of Patinopecten Yessoensis In The Waters Adjcent To Zhangzidao Island

This thesis studies the species composition, distribution andchanges of cell abundance, dominant species, community diversity ofphytoplankton basing on monthly surveys in the culture area ofPatinopecten yessoensis adjacent to Zhangzidao Island from June,2011toJune,2012. The relationship of phytoplankton community structure withenvironmental factors and food composition of Patinopecten yessoensiswere analysed by multivariate analysis. It provides basic data for study onthe variation of phytoplankton community structure and the impact of thephytoplankton community structure changes on shellfish feeding.A total of4phyla,53genera and119species of phytoplankton wereidentified from the water samples throughout the year,which includs37genera and82species of Bacillariophyta,13genera and33species ofPyrrophyta,1genera and2species of chrysophyta,2genera and2species of Euglenophyta. Diatoms and dinoflagellates are the main groups, theyaccounted for68.9%and27.7%of total species, respectively. The trends ofseasonal variation of phytoplankton abandance showed a typical“bimodal variation” in this waters. The highest peak of cell abundanceappeared in October for surface water, followed by March; However, in thebottom water, the peak of cell abundance appeared in April, followed byOctober.The phytoplankton community appears seasonal succession pattern. Inthe surface waters, the four groups appeared in every season. The averagespecies number of Bacillariophyceae was not obvious different between thefour seasons, but the Pyrrophyta and Chrysophyta sharply increased inautumn; and the Euglenophyta slightly rised in the winter. In the bottomwaters, Pyrrophyta was the dominant group in autumn, whileBacillariophyceae was the dominant group in the other seasons, and theBacillariophyceae in the four seasons were different from each other, theBacillariophyceae declined in the autumn and increased in the winter andspring. The Euglenophyta also had a slight rise in the winter. The dominantspecies of phytoplankton showed significant seasonal variation, and eachmonth in the same season and the surface and bottom phytoplankton in thesame month are different.Seasonal distribution of phytoplankton abundance was uneven. Insummer, Phytoplankton cell abundance in northern Zhangzidao Island was higher than other study area in surface waters. Southwest and southeast washigher in bottom waters; The surface and bottom distribution in Autumn issimilar which appeared the western waters was higher; The surface andbottom distribution in Autumn present that northwest was slightly higher;Spring surface, higher phytoplankton cell abundance located in thenorthern island, spring ground floor western and eastern waters washigher. Four seasons phytoplankton Shannon-Wiener index and evennessindex was the same as the summer and winter surface was higher thanbottom, fall and spring surface was lower than bottom. Phytoplanktonrichness index is different, it appeared surface was lower than bottom fourseasons.Phytoplankton speies identified in stomach of Patinopectenyessoensis blongs to3phyla,23genera and36species, which includs18genera and30species of Bacillariophyta,3genera and4species ofPyrrophyta,2genera and2species of chrysophyta, but species ofEuglenophyta wasn’t found. They accounted for83.3%,11.1%and5.6%respectively.The dominant species in stomach contents was notsignificantly different in four seasons. Which were mainly the Paraliasulcata, Thalassiosira sp., Thalassiosira eccentric, Coscinodiscus sp.,Coscinodiscus radiates, Pleurosigma sp., Ditylum brightwellii, Dictyochafibula.The similarity analysis showed that phytoplankton species grazed byPatinopecten yessoensis accounted for more than half of the species in the waters. But the main species which they feed were only limited groups,such as, the Paralia spp., Thalassiosira spp., Coscinodiscus spp. andPleurosigma spp. The study was carried out in open natural waters, whichis helpful for exploring the relationship between phytoplanktonpopulation dynamics and shellfish of bottom sowing culture, and providinga reference for the construction of marine ranching.