Project: Quantitative importance and trophic role of Noctiluca blooms in the Arabian Sea

Until the late 90's Noctiluca miliaris, a large heterotrophic dinoflagellate was a minor component of phytoplankton populations in the northern Arabian Sea, appearing in bloom form only sporadically during the Southwest Monsoon (SWM, summer monsoon) and in coastal regions predisposed to upwelling and deep slope water intrusions. Since then N. miliaris blooms have increased in frequency, intensity and distribution, but with the majority of blooms being observed during the Northeast monsoon (NEM, winter monsoon). Large blooms of these organisms have now become more pervasive and widespread throughout the Gulf of Oman and in the western and central Arabian Sea replacing diatom-dominating blooms of the NEM that were seen frequently during the multi-disciplinary Arabian Sea, Joint Global Ocean Flux Studies (JGOFS). There is particular concern that the emergence of N. miliaris blooms and their association with waters that are nutrient-rich and undersaturated with respect to oxygen may be indicative of eutrophication of the Arabian Sea ecosystem. Such concerns are consistent with recent indications that the Arabian Sea is becoming more productive and that its permanent oxygen minimum zone is intensifying due to increased organic matter export from the euphotic zone. There is also concern that the replacement of diatoms by N. miliaris is potentially having a large impact on the food web and carbon cycling in the Arabian Sea.

This project will carry out a targeted field program aimed at understanding the emergence and fate of N. miliaris blooms. In particular the project will investigate 1) the environmental conditions facilitating large N. miliaris blooms in the Arabian Sea and 2) the trophic role of N. miliaris blooms and 3) implications of these blooms for carbon cycling and biogeochemical processes in the Arabian Sea. This field study has been devised in consultation with colleagues at the National Institute of Oceanography (NIO) & the Space Applications Centre in India who have offered ship time on board the India's research vessel R/V Sagar Kanya and laboratory facilities at NIO at no cost to this project. An existing collaboration with the Sultan Qaboos University (SQU), Oman will also allow access to data from an ongoing field program in the northern Arabian Sea.

This project will provide training to two US undergraduate students at Bigelow Laboratory and one graduate student from Univ. Texas (UT) will be involved full time. This project will provide an opportunity for students from the US to work alongside students from India. Through this truly international collaborative effort the project will encourage scientific curiosity about the response of marine ecosystems to climate change as well as foster a cross-cultural exchange of ideas. The investigators will leverage education and outreach efforts through development of a website which will be linked to Bigelow Laboratory's existing algal blooms and the Univ. Maine COSEE-OESS website. This website will be translated into Hindi, the official language of India and into Arabic, the language of Oman. This web-based resource will be tailored for non-specialist audiences with strong emphasis on visuals. At the UT Marine Science Institute. a radio segment on this research will be written for Science and the Sea, a radio program produced for National Public Radio, and played on most public radio stations nationwide (http://scienceandthesea.org/)

Associated programs: OCB Ocean Chemistry and Biochemistry) and SIBER (Sustained Indian Ocean Biochemistry and Ecosystem Research).  SIBER is cosponsored by IMBER (Integrated Marine Biogeochemistry and Ecosystem Research) and IOGOOS (Indian Ocean Global Ocean Observing System).