DISTRIBUTION OF PHYTOPLANKTON PIGMENTS AND PARTICULATE ORGANIC-CARBON IN THE COASTAL WATERS OF VISAKHAPATNAM (BAY OF BENGAL)

Phytoplankton pigments and particulate organic carbon (POC) revealed temporal and spatial variations in the coastal waters of Visakhapatnam. Chlorophyll-a (chl-a) and POC exhibited major peaks in pre and postmonsoon seasons which were attributed to higher planktonic production as a result of upwelling in the former, and favourable marine conditions in the latter. The integral mean concentration (IMC) of chl-a showed a decreasing trend from coast to offshore indicating higher fertility near the coast. A subsurface maximum (10-20 m depth) was observed with chl-a and POC coinciding with the biomass.maximum. Lower ratios of chl-b, chl-c and phaeopigments with chl-a suggested their healthy physiological state. Detritus (carbon) in POC ranged from 90.8 to 97.5% indicating its dominance over living phytoplankton carbon.