Structural Characteristics and Associated Factors Influencing Phytoplankton Abundance and Species Composition in Huangmaohai Bay, Pearl River Estuary

摘要

Temporal-spatial variations of phytoplankton abundance and species composition, as well as associated environmental factors, were investigated to understand phytoplankton succession at Huangmaohai Bay in December 2010 and August 2011. Concentrations of both chlorophyll-a and nutrient showed apparent spatial variability with significantly higher levels in the upstream area of the estuary than in the offshore area. Temporal variation of the chlorophyll-a concentration showed that the concentration in the summer was 1.25 times higher than that in the winter. Significantly higher abundances of cyanobacteria and chlorophytes were found at the upstream sites where the system was influenced by freshwater input. In contrast, diatoms and dinoflagellates primarily dominated at the downstream sites. Phytoplankton abundance was higher in the summer (629.66 x 10(4) cells/m(3)) than in the winter (466.75 x 10(4) cells/m(3)). A canonical correspondence analysis of phytoplankton community and environmental factors indicated that dissolved inorganic phosphorus, nitrogen, and salinity were the key environmental factors influencing the spatial variation of phytoplankton. Dinoflagellates, cyanobacteria, and chlorophytes were generally sensitive to salinity, whereas diatoms were generally sensitive to nutrients. Because Huangmaohai Bay is part of the Pearl River Estuary, this study not only fills a gap toward understanding this region but also aids marine protection department personnel in making effective management plans that can be put into action.