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Please use this identifier to cite or link to this item: http://drs.nio.org/drs/handle/2264/4205

Title: Distribution and ecology of the Trichodesmium spp. in the Arabian Sea: Ship and satellite studies
Authors: Parab, S.G.
Matondkar, S.G.P.
Raman, M.
Dwivedi, R.M.
Citation: 11. Biennial Pan Ocean Remote Sensing Conference (PORSEC)-2012. INCOIS; 2012;20pp.
Issue Date: 2012
Publisher: Indian National Centre for Ocean Information Services (INCOIS)
Abstract: Trichodesmium is a filamentous cyanobacteria which forms dense blooms along the west coast of India in the Arabian Sea, the Lakshadweep Sea, the Andaman Sea and the Bay of Bengal. These are high biomass blooms which are mostly surface floating. During our special cruises to the Arabian Sea we collected data to understand the seasonality of Trichodesmium spp. Trichodesmium starts appearing just after the SW monsoon in the offshore waters of the Arabian Sea. Massive blooms of Trichodesmium thiebautii are noticed when water temperatures were low (26 degrees C). T. thiebautii was also found to be distributed throughout the water column. It was also observed in the coastal waters during March and in the Lakshadweep waters during April. The OCM images taken during these observations have been used to map and estimate the concentration of T. thiebautii. Low temperatures and calm condition are required for Trichodesmium thiebautii to bloom. November-December appears to be the time during which this bloom flourishes in offshore waters of the Arabian Sea. T. erythraeum blooms were noticed in the coastal waters during the March to May and in the offshore waters during the April-May period. During the months from March-April a mixed bloom of Trichodesmium with Noctiluca miliaris was also observed. We have generated a series of OCM imageries from January to March in order to locate the appearance of these blooms in different regions of the Arabian Sea. . However in a typical Trichodesmium bloom chlorophyll a values are in the range of 2-5.905 mu gl sup(-1). We have recorded upto 99.49 percent of Trichodesmium in the phytoplankton population. The Trichodesmium filaments varied from 74 to 516400 filaments l sup(-1). Goa was found to be one of the most prominent site for Trichodesmium occurrence and the chlorophyll a level during our study varied from 187.2 to 2080 mu gl sup(-1) which is extremely high. From the data collected on various cruises it appears that the depletion of nitrate by the diatoms supplied by the upwelling during the SW monsoon triggered the T. thiebautii bloom in the offshore waters of the Arabian Sea. Similar conditions developed in the coastal waters during March-May, which witnessed with higher water temperatures causing the T. erythraeum grow in bloom. Meanwhile offshore waters are conducive for Trichodesmium after April as they support mixed blooms of the Trichodesmium spp. in the offshore region. These events have been depicted by satellite images and discussed.
Document type: Conference Article
Copyright: Copyright [2012]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
URI: http://drs.nio.org/drs/handle/2264/4205
Appears in Collections:Biological Sciences

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