Fluxes of diatoms in the Dona Paula Bay, west coast of India

Abstract

Sediment traps were deployed at a station in the Dona Paula Bay to collect sedimenting particles at weekly intervals from November to May during 1995-1997. Sedimented particles were analysed for total diatom flux, chlorophyll a (Chl a) and particulate organic carbon (POC). The highest diatom flux was recorded in April-May for both the years. Fluxes of diatoms varied from 0.6 x 104 cells m-2 day-1 (November 1995) to 121.47 x 104 cells m-2 day-1 (December 1996). In all, 19 diatom genera were identified in the sedimented material. Navicula, Nitzschia, Pleurosigma, Licmophora, Coscinodiscus, Rhizosolenia and Surirella were the most abundant genera in the sedimented material throughout the sampling period. Mean flux of POC and diatom carbon was 251 and 0.39 mg C m-2 day-1, respectively. The diatom carbon accounted for 0.15% of the POC flux. Mass flux of diatoms showed significant negative correlation with the concentration of nitrate and phosphate. This suggests that the nutrient concentration played an important role in influencing the sedimentation of diatoms at this coastal station.