Studies On Phytoplankton Community Structure And Sexual Maturation Of The Pacific Oyster

Rushan Bay located on Shandong Peninsula is one of the most important sea areas for aquaculture of marine bivalves in Shandong Province in China. To analyze the environmental conditions of the Rushan Bay for mariculture, and to provide basic information for construction of appropriate fisheries management programs, we investigated the environmental factors (temperature, salinity, pH, dissolved oxygen, diaphaneity, chlorophyll a, COD, NO2-N, NO3-N, NH4-N, PO4-P and turbidity), sediment quality (sulfides and organic matters, contents of nitrogen and burning wastage), species composition and cell abundance variation of phytoplankton, growth and sexual maturation of oysters from March 2004 to February 2005 in the culture areas of Rushan Bay, and obtained a great deal of valuable data. Because we found that food availability was limited by seasonal hydrographic conditions, an experiment was conducted to determine the effect of starvation on the growth and sexual maturation of oysters from April 21st to July 21st, 2005.The results indicated that the average temperature of seawater in Rushan Bay was 15℃. The highest value appeared in August (29.5℃); the lowest value appeared in January (1.8℃). The average salinity was 29.32, and the annual salinity changed little. Summer (June-August) is the rainy season of Rushan Bay, salinity is comparatively lower than other months because the rainfall increases. The lowest value appeared in August (26.37), while the highest value appeared in December (33.21). The dissolved oxygen ranged from 5.25 mg/L to 8.08 mg/L, with the annual average of 7.45 mg/L. pH value ranged from 7.73 to 8.18, being consistent with the national second-class seawater standard (GB 3097-1997). The annual diaphaneity ranged from 87 to 285cm, indicating the seawater quality was excellent. The chlorophyll a level was lowest in December (1.24 mg/m3), and highest in September (25.79 mg/m3), and the second highest value was 17.70 mg/m3 in April. The dissolved inorganic nitrogen ranged from 0.205 to 0.464 mg/L, with the annual average of 0.345 mg/L, in agreement with the national third-class seawater standard. The phosphate content fluncated between 0.019 mg/L and 0.085 mg/L, with the annual average of 0.050 mg/L, in agreement with the national second-class seawater standard. N:P was between 2.41...