Study of chlorophyll a distribution in marine ranching planning area of Xiangshan Bay

Abstract:

In order to realize the state of primary productivity in marine ranching planning area of Xiangshan Bay and provide basis for the effect evaluation of marine ranching construction, seasonal investigations of 22 sites in Zhejiang Province were carried out in April, July and November of 2011. Experiment results about ecological factors, such as Chlorophyll a concentration, stability of water, temperature, nutrient contents in water and sediment, were analyzed with correlation analysis method. Results presented an obvious seasonal variation of Chlorophyll a in the study area, for the Chlorophyll a concentrations were 4.62 mg/m3 in April, 3.57 mg/m3 in July and 3.11 mg/m3 in November (April>July>November).The horizontal distribution of Chlorophyll a was gradually reduced from the bottom to the mouth of the bay and in the vertical direction, the Chlorophyll a concentrations were 3.02 mg/m3 in July, 1.93 mg/m3 in April and 1.61 mg/m3 in November (July>April>November). Results also showed Chlorophyll a concentration got remarkably positive correlations with turbidity, water temperature, salinity and active phosphate, while presented a negative correlation with the stability of water. Sediment in this research area was rich in nitrogen and phosphorus nutrients, and it is supposed to reduce PEAP when artificial reefs are reconstructed, to help promote the regeneration of nutrients, which will be conducive to the growth of phytoplankton and the elevation of primary productivity level.