Variation in the composition of carbohydrates in the Dona Paula Bay (west of India) during May/June 1998

Suspended particulate material was analysed for particulate carbohydrate co ncentration and composition and for the bulk parameters: suspended particul ate matter, chlorophyll a, particulate organic carbon, particulate organic nitrogen and particulate proteins. Chlorophyll a concentrations increased f rom May 7 to 15 due to the development of a small scale bloom of diatom Nav icula sp. and decreased for the remaining period after the premonsoon rain on 16 and 17 May. Concentrations of particulate organic carbon, organic nit rogen, carbohydrates and proteins increased with the increase in chlorophyl l a concentration. Together particulate protein-carbon and carbohydrate-car bon accounted for 10 to 30% of the organic carbon. Glucose contributed 26 t o 81% to the total particulate carbohydrates. The decrease in glucose conce ntration was accompanied by the increase in mannose, galactose, xylose, ara binose, rhamnose and fucose. Chlorophyll a showed significant positive rela tionship with glucose and negative relationships with arabinose and xylose. Conversely, suspended particulate matter showed significant positive relat ionships with xylose and arabinose and negative relationships with chloroph yll a and glucose. The hexoses to pentoses ratio increased during 7 to 15 M ay and decreased thereafter. Relatively higher chlorophyll a, particulate p rotein-carbon plus carbohydrate-carbon, glucose, hexoses:pentoses ratio and lower rhamnose plus fucose suggested the presence of more fresh marine org anic matter during May 8 to 15. Subsequently, chlorophyll a, contribution o f particulate protein-carbon plus carbohydrates-carbon to organic carbon, h exoses to pentoses ratio, and weight percentage of glucose decreased wherea s, weight percentage of rhamnose plus fucose, arabinose and xylose increase d, reflecting highly degraded diagenetically altered particulate organic ma tter from May 16 to June 2. The carbohydrate content and composition as wel l as protein data suggest that the nature and source of organic matter Vari ed within a few days at this tropical coastal site. Such variability in the nutritional quality of organic matter may have a strong influence on the m etabolic activity of filter feeding organisms. (C) 2001 Ifremer/CNRS/IRD/Ed itions scientifiques et medicales Elsevier SAS.