Satellite and ship studies of phytoplankton in the Northeastern Arabian during 2000 – 2006 period

Sequence of the images from IRS P4 / OCM satellite and extensive shipboard sampling programme are used to understand the seasonal variation of phytoplankton abundance and types in the Northeastern (NE) Arabian Sea and Lakshadweep Sea. An appreciable degree of spatial and temporal variability is observed in chlorophyll a distribution from November to April months, as well as coastal and offshore stations, indicating marked seasonality in phytoplankton distribution in NE Arabian Sea. During November month (fall intermonsoon) average chlorophyll a (Chl a) by fluorometer was (0.799 mgm-3) and by OCM it was 0.584 mgm-3. The higher chlorophyll a observed was due to Trichodesmium (cyanobacteria) blooms. During December the average chlorophyll a was 0.34 mgm-3 also due to Trichodesmium filaments in water column. During January onwards winter cooling led to increase in nutrients which enhanced chlorophyll a value to 0.64 mgm-3due to growth of flagellates (as seen by high chlorophyll b besides chlorophyll a) in water column. February, March and April supported moderately high chlorophyll value (0. 3 to 0.5 mgm-3) due to growth of prasinophytes (as seen by pigment prasinoxanthin) and blooms of the Noctiluca miliaris. Time series monitoring of Noctiluca bloom was also conducted using OCM based chlorophyll images in NE Arabian Sea. During February chlorophyll a retrieved by OCM was 0.3 to 0.9 mgm-3. Pigment analysis of water samples indicated the equal important of accessory pigment like zeaxanthin, prasinoxanthin, β-carotene. The relevance of these pigment