Journal of the Marine Biological Association of India

UV radiation and natural fluorescence linked primary F roduction in Antarctic waters.

Volume 43 Issue 1&2

A. Lokabharathi, L. Krishnakumari, P. M. A. Bhattathiri and C. Chandramohan

Abstract

Primary productivity chlorophyll values have been measured an underwater profiling radiometer for the first time in the waters around Indian Antarctic Station (70⁰46´S &11⁰44Ein the summer of 1994. The profiles include natural fluorescene (upwelled radiance at 683 nm), scalar irradiance (photosynthetically active radiation, PAR), computed primary production (pp), diffuse attenuation coefficient , UV B (308 and 320 nm) and UV a (340 and 380nm) radiation, and water temperature, measured as a function of depth from 21/01/94 to 6/03/94. The profiles covered measurements between 2-75 metre depth. Fifteen observations were made at an anchored stations in Antarctic waters (69⁰53’ to 70⁰02’S) Sub-surface chlorophyll ranged from 0.2 to 0.5 mg m^-3. Range in colomn chlorophyll was 6.6 to 71 mg m^-3. The average values  sub surface chlorophyll a and pp was 0.3 mg m^-3 and 6.3 mg CM^-3 hr ^-1respectively. The mean value for column chlorophyll was 19.2 mg ^-2 and primary productivity 102.4mg CM^-2hr^-1. Interestingly, positive correlations were observed between primary productivity values were normalized for PAR, a more negative effects was noticed in the sub-surface and column waters and his negative effect was significant at 1% level (p<0.01) in column waters. This response in the photosynthetic parameters could be due to the varied effect of UV A and UV B on phytoplankton.

 

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Date : 30-12-2001