Variability of Particulate Amino Acids and Processes Responsible for Sources into the Coastal Waters of the Bay of Bengal

• Published in: Estuaries and coasts 2024, Vol.47 (1), p.117-127
• Main Authors: Kumar, B. S. K., Rao, D Bhaskara, Surendra, T., Rao, Ch. V., Meshram, M. P.
• Format: Article
• Language: English
• Subjects: Amino acid composition; Amino acids; Aquatic ecosystems; Biological activity; Coastal processes; Coastal Sciences; Coastal waters; D-Galactosamine; Earth and Environmental Science; Ecology; Environment; Environmental Management; Freshwater & Marine Ecology; Glucosamine; Heterotrophic organisms; Heterotrophs; Hexosamines; Monsoons; Organic carbon; Organic matter; Organic soils; Phytoplankton; Precipitation; Resuspension; River discharge; River flow; Runoff; Seasonal variation; Seasonal variations; Suspended matter; Terrestrial ecosystems; Terrestrial environments; Water analysis; Water and Health; Water sampling; Wind
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-023-01262-2

Amino acids are the more labile compounds of organic matter in aquatic and terrestrial ecosystems. The variability of particulate amino acids in coastal waters depends on several biological (in situ production, grazing by heterotrophs) and physical (river discharge, terrestrial runoff, precipitation) processes. Coastal water samples of the Bay of Bengal were collected at three fixed locations from surface to 100m depth to investigate seasonal variability, transformation, and degradation of amino acids and their sources in Bay of Bengal coastal waters. Various biogeochemical parameters were collected along with particulate amino acids to understand their impact on amino acid composition distribution and variability. Particulate amino acids vary from 0.21 to 7.1µ mol/L, and the highest concentrations are during the non-monsoon period (4.3 µ mol/L) than the monsoon period (2.5 µ mol/L). During the non-monsoon period, amino acids show a significant linear positive relation with phytoplankton biomass (Chl-a) and suspended matter in the monsoon period. The relations indicate that amino acids during the non-monsoon were contributed from the in situ production and during the monsoon from terrestrial inputs. The ratio of amino acids to hexosamines (AAs/HAs) and the ratios of glucosamine (Glc-NH 2 ) to galactosamine (Gal-NH 2 ) were on average 15.5 and 5.2 in non-monsoon and during monsoon; they were 3.3 and 2.1, indicating that during the monsoon period, the amino acids were more of aged and which could be from resuspension of soil or refractory organic matter, which could enter the coastal waters because of precipitation and in non-monsoon, the higher ratios suggesting that in situ biological processes contributed these amino acids. This study indicated that during the monsoon period, physical processes like precipitation, terrestrial runoff, sediment resuspension, and non-monsoon period biological processes like in situ production significantly contribute organic carbon to the coastal waters of the Bay of Bengal.