Summary of Abstract Submission

Abstract Submission No. IO50-02-0012PresentationOral

SEDIMENT DYNAMICS IN THE OXYGEN MINIMUM ZONE OF THE ARABIAN SEA: RESULTS FROM IN SITU OBSERVATIONS, MEASUREMENTS AND EXPERIMENTS ACROSS LOWER OMZ TRANSITION WITH HOV SHINKAI 6500

Hiroshi Kitazato*1, SWA Naqvi2, Greg Cowie3

1 JAMSTEC, Japan
2 NIO, India
3 Edinburgh University, UK

ABSTRACT :

In order to elucidate depositional processes, biogeochemical cycles and deep-sea biology at the sediment-water interface (SWI) under oxygen depleted environm. ents, we conducted a multidisciplinary research cruise (YK08-11) off the Indian continental margin in the Arabian Sea. This is the first HOV dive cruise in the Indian EEZ of the Arabian Sea. During the cruise, we carried out sea floor observations using a human-occupied vehicle (HOV), Shinkai 6500. Planer optode and CTD sensors assembled on an Elinor-type lander, benthic chambers, and deep-sea stereo camera systems mounted on the HOV were used for monitoring and measuring chemical fluxes across the SWI. In-situ feeding experiments with 13C labeled organic materials were carried out by submersible for calculating the carbon budget across the OMZ. Further shipboard incubation studies were carried out in which oxygen concentration and food supply were manipulated to assess their impacts on benthic community function and biogeochemical fluxes. Precise observations of OMZ were also made with HOV for understanding benthic faunal communities, sediment geochemistry and oxygen dynamics. Microbial activities are measured both in waters and sediments for understanding biogeochemical cycles at OMZ. During the International Symposium on the Indian Ocean, we plan to overview results from our research cruise and give suggestions for the future OMZ studies, in the Arabian Sea and more widely in the Indian Ocean.