To study the effect of hydrographic factors on the spatial distributions of chlorophyll a （Chl a）, an investigation was carried out in the tropical eastern Indian Ocean （80 –100 E along 7 S, and 7 –18 S along 80 ...To study the effect of hydrographic factors on the spatial distributions of chlorophyll a （Chl a）, an investigation was carried out in the tropical eastern Indian Ocean （80 –100 E along 7 S, and 7 –18 S along 80 E） in December 2010. The fluorescent method was used to obtain total Chl a and size-fractioned Chl a at the 26 stations. The results show that surface Chl a concentration averaged at （0.168 ± 0.095） mg/m 3 s.d. （range： 0.034–0.475 mg/m 3 ）, concentrations appeared to be higher in the west for longitudinal variations, and higher in the north for latitudinal variations. Furthermore, the surface Chl a concentration was lower （0.034–0.066 mg/m 3 ） in the region to the south of 16 S. There was a strong subsurface Chl a maximum layer at all stations and the depth of the Chl a maximum increased towards to the east and south along with the respective nitracline. The spatial variation of Chl a was significant： correlation and regression analysis suggests that it was primarily affected by PO 3 4 , N（NO 3 –N＋NO 2 –N） and temperature. Size-fractionated Chl a concentration clearly showed that the study area was a typical oligotrophic open ocean, in which picophytoplankton dominated, accounting for approximately 67.8% of total Chl a, followed by nanophytoplankton （24.5%） and microphytoplankton （7.6%）. The two larger fractions were sensitive to the limitation of P, while picophytoplankton was primarily affected by temperature.展开更多
基金China Ocean Mineral Resources R & D Association under contract No. DY125-13-E-01the Scientific Research Fund of the Second Institute of Oceanography, State Oceanic Administration under contract No. JG1024
文摘To study the effect of hydrographic factors on the spatial distributions of chlorophyll a （Chl a）, an investigation was carried out in the tropical eastern Indian Ocean （80 –100 E along 7 S, and 7 –18 S along 80 E） in December 2010. The fluorescent method was used to obtain total Chl a and size-fractioned Chl a at the 26 stations. The results show that surface Chl a concentration averaged at （0.168 ± 0.095） mg/m 3 s.d. （range： 0.034–0.475 mg/m 3 ）, concentrations appeared to be higher in the west for longitudinal variations, and higher in the north for latitudinal variations. Furthermore, the surface Chl a concentration was lower （0.034–0.066 mg/m 3 ） in the region to the south of 16 S. There was a strong subsurface Chl a maximum layer at all stations and the depth of the Chl a maximum increased towards to the east and south along with the respective nitracline. The spatial variation of Chl a was significant： correlation and regression analysis suggests that it was primarily affected by PO 3 4 , N（NO 3 –N＋NO 2 –N） and temperature. Size-fractionated Chl a concentration clearly showed that the study area was a typical oligotrophic open ocean, in which picophytoplankton dominated, accounting for approximately 67.8% of total Chl a, followed by nanophytoplankton （24.5%） and microphytoplankton （7.6%）. The two larger fractions were sensitive to the limitation of P, while picophytoplankton was primarily affected by temperature.
