Summary of Abstract Submission

Abstract Submission No. IO50-09-0056PresentationPoster


Jabir Thajudeen*1, Sudheesh V1, Jesmi Yousuf2, Gupta GVM3, Mohamed Hatha**2

1 Cochin University of Science and Technology, India
2 Cochin University of Sciences and Technology, India
3 Centre for Marine Living Resources and Ecology, India


Marine bacterioplankton (BP) and autotrophic picoplankton (APP) have vital role in the cycling of carbon and nutrients in the marine environment. Abundance, biomass, spatial and vertical distribution of bacterioplankton and picophytoplankton and its relationship with environmental parameters were investigated seasonally along the coast of South eastern Arabian sea (SEAS; Cochin Transect) (up to 100m) during 2012. The results showed significant seasonal variation in the abundance and biomass of BP and APP. While the APP abundance ranged from 7.5x101- 6.28 x105 cells/L, biomass ranged from 0.004 - 34.55 g m-3 (av. 4.97 7.88 g m-3). While pre-monsoon recorded highest abundance (2.1 x103 - 6.28 x105 cells/L) and biomass 0.12 -34.55 g m-3 (av. 5.23 8.12 g m-3), post-monsoon season showed lower APP abundance (90-9.65x104) and biomass (0.004-5.3 g m-3). Highest BP abundance (1.82x108 to 2.69x1010 cell/ml) and biomass (avg. 33.331.8 gm-3) was during the nutrient rich monsoon season compared to premonsoon and post monsoon seasons (5.672.55 gm-3, 6.91 5.7 g m-3 respectively). APP community structure showed spatial variation (from 10 to 100m), the availability of nutrients was important factor affecting the variability in biomass. The biomass of APP was high in slightly eutrophic waters when compared to oligotrophic waters. Vertical distribution of BP and APP revealed higher concentration of these organisms in the region of subsurface chlorophyll maxima. BP and APP showed significant negative correlation (r = -0.70, -0.53; P<0.05) with salinity. Significant negative correlation was also observed between nutrients and APP, although positive correlation was observed between APP and BPP. APP seemed to be important source of carbon production especially under oligotrophic conditions in the Southeastern Arabian Sea. BP play potential role in carbon export, as they have higher turnover number and important role in remineralisation process.