Some of the strongest atmospheric forcing of oceanic properties anywhere on our planet is observed in the Arabian Sea, where seasonally reversing monsoon winds drive fast-flowing, vertically extensive currents, complex eddy-fields, broad-scale, open-ocean upwelling, coastal upwelling, and pronounced mixed-layer deepening. Cycles of production in this region are driven by the ocean's response to monsoon winds and therefore exhibit large and regular seasonal oscillations. During the south-west monsoon season (June September, inclusive), primary productivity is maximal, owing to strong winds that not only cause the uplift of deep water rich in nutrients, but also deliver aeolian dust to the surface layer of this tropical ocean. During the north-east monsoon (December-February, inclusive) and intermonsoon periods, primary productivity is markedly reduced. Biomass of epipelagic zooplankton and secondary productivity are also elevated during the south-west monsoon season. The community structure of the epipelagic mesozooplankton undergoes significantly changes from one monsoon season to another with biomass, during the south-west monsoon, dominated by rapidly growing copepod species such a Calanoides carinatus and Eucalanus monachus. These species exist in a lipid-fueled diapause at subsurface depths during other seasons. The seasonal appearance of relatively large, fast-growing grazers, whose nauplii and early copepodid stages are important, and abundant components of the microzooplankton of the Arabian Sea could be a dominant factor governing food-chain transfers to higher trophic levels (myctophids) that also exhibit annual production cycles.
- Arabian Sea
- mesozooplankton copepods
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science