On the coupling of hydrography, phytoplankton, zooplankton, and settling organic particles offshore in the Arabian Sea

Abstract

Processes and issues related to the connections between hydrography, plankton, and the flux of organic carbon to great depth are reviewed for the offshore Arabian Sea and compared with observations in similar regimes of other seas. The south-north and west-east gradients and seasonality in the Arabian Sea are emphasized, but generalizations about the area as a whole are shunned. New data include regional differences in seasonality of satellite-observed chlorophyll for two years. The rule for the depth dependence of organic flux is unclear, therefore, this should be the first priority for future investigations. While the data for supply of organic carbon by settling and demand for the depth interval 200–1,000 m in the eastern Arabian Sea are in fair agreement, this is not true for the interval between 300 and 400 m. For advancing the understanding of the generation of flux in the upper layers and the consumption at depth, very much needs to be learned about the biology of the principal species of Zooplankton and nekton. To keep the task manageable, further studies of flux should focus on only one or two subdivisions of the Arabian Sea.