Abundance and relationship of bacteria with transparent exopolymer particles during the 1996 summer monsoon in the Arabian Sea

Abstract

Bacterial abundance and production, numbers, sizes and concentrations of transparent exopolymer particles (TEP) and total organic carbon (TOC) were measured during the 1996 summer monsoon to understand the relationship between TEP, the most labile particulate organic carbon, and bacteria. While high regional variability in the vertical distribution of TOC was discernible, TEP concentrations were high in surface waters at 18--20 N along 64 E with concentrations well over 25 mg alginic acid equivalents l À1 due to upwelling induced productivity. Their concentrations decreased with depth and were lower between 200 and 500 m. Bacterial concentrations were up to 1.99 Â 10 8 l À1 in the surface waters and decreased by an order of magnitude or more at depths below 500 m. A better relationship has been found between bacterial abundance and concentrations of TEP than between bacteria and TOC, indicating that bacterial metabolism is fueled by availability of TEP in the Arabian Sea. Assuming a carbon assimilation of 33%, bacterial carbon demand (BCD) is estimated to be 1.017 to 4.035 g C m À2 d À1 in the surface waters. The observed TEP concentrations appear to be sufficient in meeting the surface and subsurface BCD in the northern Arabian Sea.

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

“…In the present study, TBA in the surface waters of Dona Paula bay was similar to those reported from the offshore waters of the Arabian Sea and showed a weak inverse correlation with TEP. Our observations go well with the open-ocean observations of Ramaiah et al (2000) suggesting that bacteria might not be using TEP as an organic carbon source in these waters and may not have influenced the dynamics of TEP.…”

“…Similarly, Kiorbøe and Jansen (1993) also found that bacterial cells were attached to TEP and suggested the probable role of TEP as carbon source to support the bacterial carbon demand. In contrast, Ramaiah et al (2000) did not find any clear correlation between bacterial biomass and TEP distribution in the Arabian Sea. In the present study, TBA in the surface waters of Dona Paula bay was similar to those reported from the offshore waters of the Arabian Sea and showed a weak inverse correlation with TEP.…”

“…Since exudates and/or extracellular polymers are highly sticky in nature (Alldredge et al, 1993;Passow et al, 1994), they bind suspended particulate matter and are considered vital for the formation of aggregates (Engel 2004). Microbial exudates and cell envelopes remain attached to the cell-wall either as tight capsules (extracted by EDTA and referred hereafter as CPCHO) or as loosely attached slimes (extracted by 1.5M NaCl and referred hereafter as Sal-PCHO) (Bhosle et al, 1995;Underwood et 3 and bacteria (Passow 2002 and the references therein), macroalgae (Ramaiah et al 2000, Thornton 2004), marine invertebrates (McKee et al 2000) and benthic biofilms (Decho 2000) are some of the important sources for the production of TEP. Since both TEP and particle-associated carbohydrates have similar sources and are a rich source of organic carbon, their distribution and biogeochemical transformations in a coastal environment is important to understand its role in sustaining the carbon demand in the near-shore waters.…”

“…The few reports on the distribution of TEP in the tropical waters are based on a one time measurements in the oceanic waters of the Bay of Bengal and Arabian Sea (Kumar et al 1998;Ramaiah et al, 2000).…”

Interactive network configuration maintains bacterioplankton community structure under elevated CO<sub>2</sub> in a eutrophic coastal mesocosm experiment

“…Some replicates were missing at day 4 because we were able to successfully extract enough DNA for sequencing only from bag 1, bag 7 and bag 6, also probably due to high TEP at day 4. It has been reported that high TEP concentration is typically associated with high bacteria biomass (Sugimoto et al, 2007;Ramaiah et al, 2000). Bacterioplankton abundance data ( Fig.…”