Relationship between distribution of chlorophyll a and main environmental factors in Liusha Bay

From Feb.to Nov.2008,spatial and temporal distributions of concentration of chlorophyll a were surveyed in four seasons in Liusha Bay,and the results showed that the concentration of chlorophyll-a ranged from 0.47 mg/m3 to 6.35mg/m3,with an annual average of 2.65 mg/m3.The average concentration of chlorophyll-a was 2.49 mg/m3 in spring,3.81mg/m3 in summer,2.77 mg/m3 in autumn and 1.46 mg/m3 in winter respectively,so the seasonal pattern of chlorophyll-a was summerautumnspringwinter.The highest average concentration of chlorophyll-a was found at station 9(3.38 mg/m3) in fish mariculture areas,while the lowest one presented at station(21.35 mg/m3)in outside bay.The difference in concentration of chlorophyll a among stations was not significant(P0.05),nor did the difference in that between inner stations and outer station.Correlation analysis showed that the concentration of Chlorophyll-a was significantly negative relative to NO2--N,NO3--N,and salinity in this investigation.The water was oligotrophic in Liusha Bay with the chlorophyll a as the assessment criteria.The lower concentration of chlorophyll a might be related to the low content of inorganic nutrients,competitive utilization for inorganic nutrients by algae and sea grass bed,strong water exchange,and grazing phytoplankton by zooplankton and seashells.