TT33A:
Biogeochemical and Ecological Impacts of Boundary Currents in the Indian Ocean

Session ID#: 84748

Session Description:
Monsoon forcing and the unique geomorphology of the Indian Ocean basin result in complex boundary currents, which are unique in many respects. In the northern Indian Ocean, several boundary current systems reverse seasonally.  Although the transport of most of these currents is relatively modest, the current reversals give rise to dramatic changes in productivity, nutrient stoichiometry and higher trophic level behavior. Off the coast of Java, monsoon-driven changes in the currents and upwelling strongly impact chlorophyll concentrations, seasonal vertical migrations of zooplankton, and sardine catch.

In the southern hemisphere the Leeuwin is a relatively small, downwelling-favorable current that flows southward along western Australia.  This current sheds anomalous, relatively high chlorophyll, warm-core, downwelling eddies that transport coastal diatoms and larvae westward into open ocean waters. In contrast, the transport of the Agulhas Current is very large. Meanders and eddies in the Agulhas Current propagate alongshore and interact with seasonal changes in the winds and topographic features, which give rise to seasonally variable localized upwelling and downwelling circulations with commensurate changes in primary production and higher trophic level responses.

There is evidence from the paleoceanographic record that these currents and their biogeochemical and ecological impacts have changed significantly over interglacial timescales.

Co-Sponsor(s):
  • CP - Coastal and Estuarine Processes
  • PI - Physical-Biological Interactions
Index Terms:

4512 Currents [OCEANOGRAPHY: PHYSICAL]
4815 Ecosystems, structure, dynamics, and modeling [OCEANOGRAPHY: BIOLOGICAL]
4936 Interglacial [PALEOCEANOGRAPHY]
9340 Indian Ocean [GEOGRAPHIC LOCATION]
Primary Presenter:  Raleigh R Hood, University of Maryland Center for Environmental Science Horn Point Laboratory, Cambridge, MD, United States
Moderators:  James B Edson, Univ Connecticut, Groton, United States and Carol Anne Clayson, Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, MA, United States

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