Spatial variation of phytoplankton pigments along the southwest coast of India

Phytoplankton composition and abundance were studied along the southwestern Indian coast toward the end of the upwelling season in October 2004. Phytoplankton pigment analyses, complemented by limited microscopic counts, were carried out to determine the community structure. Chlorophyll a was the most abundant of all pigments, followed by fucoxanthin. Zeaxanthin was abundantly found in the southern part of the study region (off Trivandrum), whereas fucoxanthin was the dominant marker pigment in the north (off Goa). The inferred shift in the community structure from a dominant picoplankton fraction and Prymnesiophytes to diatom-dominated microplankton toward the north is ascribed to differences in the physico-chemical environment.