Summary of Abstract Submission

Abstract Submission No. IO50-10-0006PresentationPoster

MAPPING MARINE CYANOBACTERIUM TRICHODESMIUM IN THE COASTAL WATERS OF WEST COAST OF INDIA USING AQUA-MODIS DATA

R. Dwivedi*1, S.G.P. Matondkar2, Aneesh Lotlikar3, Srinivasa Kumar3, M. Sudhakar1, S.S.C. Shenoi3

1 Centre for Marine Living Resources & Ecology, Kochi, India
2 National Institute of Oceanography, Goa, India
3 Indian National Centre for Ocean Information Services, Hyderabad, India

ABSTRACT :

Trichodesmium, the photosynthetic cyanobacterium, fixes atmospheric nitrogen when nutrient depleted stratified water mass prevails during the summer. This makes it an important biogeochemical component of the marine ecosystem. A ship cruise was conducted to study the environmental conditions responsible for causing this bloom during April 2006. Peak bloom of Trichodesmium erythreum was observed in the coastal waters off Porbandar (21.7o N), Veraval (20.5o N) and Goa (15.5o N). An occurrence of this bloom is sporadic in nature and hence, the development of remote sensing technique for the detection enables knowledge of its distribution in space and time. The reflectance spectra for this bloom have a unique shape probably due to its nitrogen containing pigments phycoerythrin and phycocyanin. An approach for detection of this species basically considers recognition of spectral shape of the reflectance spectra for bloom and normal waters. The discrimination criteria for this purpose were developed from the spectral reflectance characteristics generated from Aqua-MODIS data for different water types. Trichomesmium species images were generated using species-specific threshold and MODIS data. It was observed that Trichodesmium detected from the satellite data matched with ship observations of 2006. This paper highlights adequacy of MODIS data for detecting Trichomesmium in the Indian coastal waters. Remote detection has potential to serve as a tool for the surveillance of this bloom from space for which shipboard observations seem ineffective due to their sparse spatial and temporal scales.