Temporal-spatial Variation Of Phytoplankton Chlorophyll And Particulate Inorganic Carbon In The Beibu Gulf

Marine phytoplankton are the main primary producers of marine ecosystems, which not only form the base of the marine food web, and its contribution to the entire biosphere accounts for about 50% of the global net primary production; And marine phytoplankton photosynthesis regulates also volume of carbon dioxide in the atmosphere. Utilizing satellite data, we investigate temporal-spatial variation of phytoplankton in the Beibu Gulf, and discuss the physical and biological mechanism of phytoplankton variation.Phytoplankton chlorophyll a(Chl-a) and particulate inorganic carbon presented significant temporal-spatial variation in the Beibu Gulf. The results showed that the pattern of phytoplankton distribution may be related with the monsoon reversal, sea surface temperature, aerosol optical thickness, tides, rivers’ runoff, etcto some degree. Study results have indicated that there is a good positive correlation(R=0.81,P P<0.05) between the particulate inorganic carbon concentration(PIC) and wind speed; and negative correlation between PIC andtemperature(R=-0.35, P<0.05) in the Beibu Gulf. Following the above studies, linear correlation analysis based on three different areas indicated further that(1)Phytoplankton Chl-a / PIC concentration was positively correlated with aerosol optical thickness(R=0.5,P<0.05)/(R=0.4,P<0.05)and wind speed(R=0.5, P<0.05)/(R=0.52, P<0.05)in the central of Beibu Gulf;(2)Phytoplankton Chl-a / PIC concentration was positively correlated with aerosol optical thickness(R=0.3, P<0.05)/(R=0.07,P<0.05)and weak correlation with wind speed(R=0.03, P<0.05)/(R=0.3, P<0.05)in the west coast of leizhou peninsula;(3)Phytoplankton Chl-a /PIC concentration was positively correlated with aerosol optical thickness(R=0.2, P<0.05)/(R=0.015, P<0.05)、and wind speed(R=0.5, P<0.05)/(R=0.5,P<0.05)in the west coast of hainan island. The highest Chl-a concentration in the Central Beibu gulf occurs in winter when aerosol optical thickness is the thickest with one good correlation(R=0.5,P<0.005), suggesting that aerosol precipitation may play important role in the Chl-a seasonality; High Chl-a concentration in the west coastal region of Leizhou peninsula is related to strong northeast monsoon and tidal mixing. Year-round high Chl-a concentration may be associated with strong monsoon and runoff of the rivers as well as shallower depth, which carry nutrients into the western coastal region of the western Hainan. In summary, Temporal-spatial variation of phytoplankton is closely regulated by the oceanographical environments and climate conditions(such as, wind, sea surface temperatures,aerosol, tides, river runoff) in the Beibu Gulf.