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

摘要

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: 1. transparent exopolymeric particles (TEP) concentration, 2. two forms of particle-associated carbohydrates - 1.5 M NaCl/saline extracted (Sal-PCHO) and 10 mM EDTA-extracted (CPCHO) and 3. total bacterial abundance (TBA) to particulate organic carbon pool. A distinct inter-annual variability was observed with an increase in the bacterial abundance, chlorophyll 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 carbon 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.