Journal of the Marine Biological Association of India

Volume 43 Issue 1&2

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

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

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.




Date : 30-12-2001