Dynamics of transparent exopolymeric particles (TEP) and particle-associated carbohydrates in the Dona Paula bay, west coast of India

Surface seawater samples were collected over a period of 27 months at a shallow water station in Dona Paula bay from 1998–2000. The samples were analyzed to assess the seasonal variations, inter-annual variability and the contributions of: • transparent exopolymeric particles (TEP) concentration, • two forms of particle-associated carbohydrates – 1.5M NaCl/saline extracted (Sal-PCHO) and 10mM EDTA-extracted (CPCHO) and • total bacterial abundance (TBA) to particulate organic carbon pool. A distinct inter-annual variability was observed with an increase in the bacterial abundance, chloro-phyll a (Chl a), TEP and Sal-PCHO and their greater contribution to particulate organic carbon during May 1998–1999 than in June 1999–July 2000. Overall, there was no statistically significant correlation of TEP with phytoplankton biomass (Chl a), Sal-PCHO, CPCHO and hydrodynamic conditions. A weak inverse correlation was observed between TEP and TBA (r = −0.397; p < 0.05) but the role of TEP as a C-source for bacteria was not evident. Both Sal-PCHO and CPCHO appeared to be two distinct forms of carbohydrates. Unlike CPCHO, Sal-PCHO concentrations showed a positive trend with Chl a and significant linear correlation with bacterial abundance (r = 0.44, p < 0.007, n = 48), indicating that Sal-PCHO as carbon source might have supported bacterioplankton abundance. The mean %TEP-C contribution to the annual average organic car-bon for 1998–2000 was 6.9 % ± 5.8%, next only to phytoplankton-C (33.1 ± 22.1%) and greater than bacterial-C (4.6 % ± 4.6%) or carbohydrate-C (< 3.8%). Despite its greater contribution to the organic carbon pool, the contribution of TEP-C to the benthic carbon demand and its fate in the study area could not be ascertained in this study. 1

Butyltins in water, biofilm, animals and sediments of the west coast of India

Biofilm, fish, oyster, mussel, clam, surface seawater, suspended particulate matter (SPM), and sediment samples were collected from marine and/or estuarine waters of the west coast of India. These samples were analysed for butyltin derivatives such as dibutyltin (DBT) and tributyltin (TBT). The concentrations DBT plus TBT varied between 2.4 and 8.3, 163 and 363 ng/l, 5 and 2853 ng/g dry wt in the SPM, seawater and sediment samples, respectively, of the Marmugao harbour. The values of DBT plus TBT ranged between 0.60 and 29, 123 and 242 ng/l and 1.4 and 65 ng/g dry wt in SPM, water and sediment samples, respectively, collected from the Mandovi estuary. In the Dona Paula Bay the DBT plus TBT varied from 10 to 89 ng/l in surface seawater, and TBT from 10 to 513 ng/g in biofilm samples. For the coastal sediment samples the concentration of DBT plus TBT ranged between 36 and 133 ng/g dry wt of sediment. For the animal samples the DBT plus TBT ranged between 58 and 825 ng/g dry wt of the tissue. Mussel tissues contained the highest amount of DBT plus TBT (825 ng/g dry wt tissue), whereas highest TBT concentration was recorded in the oyster (732 ng/g dry wt). TBT was generally the most abundant butyltin compound in most of the samples suggesting fresh inputs and/or less degradation of TBT. A wide range of the observed butyltin concentrations suggests the presence of localized areas of contamination. Leaching of tributyltin-containing antifouling paints from the ocean going ships, fishing and recreational boats, barges, and the inputs of TBT from the Goa shipyard and dry dock facility situated in the harbour are the probable sources of the DBT and TBT in the samples of the west coast of India. Higher levels of TBT were observed in biofilm relative to that in the surrounding seawater. When fed on TBT contaminated biofilm of the diatom Navicula subinflata, butyltin concentrations in the clam Paphia malabarica increased over the period of feeding suggesting the importance of biofilm in the transfer of butyltins to higher group of organisms