UV radiation and natural fluorescence linked primary production in Antarctic waters

• Main Authors: LokaBharathi, P.A., KrishnaKumari, L., Bhattathiri, P.M.A., Chandramohan, D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Marine Biological Association of India 2001
• Subjects: Primary productivity; Indian Antarctic Station; Antarctic; Indian; Antarc*
• Online Access: http://drs.nio.org/drs/handle/2264/370

Primary productivity and chlorophyll values have been measured using an underwater profiling radiometer for the first time in the waters around Indian Antarctic Station (70°46'S & 11°44'E) in the summer of 1994. The profiles include natural fluorescence (upwelled radiance at 683 run), scalar irradiance (photosynthetically active radiation, PAR), computed primary production (pp), diffuse attenuation coefficient, UV B(308 and 320 ran) and UV A (340 and 380 nm) radiation, and water temperature, measured as a function of depth from 21/1/94 to 6/3/94. The profiles covered measurements between 2-75 metre depth. Fifteen observations were made at an anchored station in Antarctic waters (69°53' to 70°02'S). Sub-surface chlorophyll ranged from 0.2 to 0.5 mg m-³ Range in column chlorophyll was 6.6 to 71 mg m-³. The average values for sub-surface chorophyll a and pp was 0.3 mg m-³ and 6.3 mgC m-³ hr-¹ respectively. The mean value for column chlorophyll was 19.2 mg m-² and primary productivity 102.4 mgC m-² hr-¹. The mean specific sub-surface productivity was 19.4 mgC m-² hr-¹. Interestingly, positive correlations were observed between primary productivity, UV A and UV B in sub-surface waters. However, when the primary productivity values were normalized for PAR, a more negative effect was noticed in the sub-surface and column waters and this 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.