The seasonal variations in distribution of photosynthetic pigments in fouredible species of Chlorophyceae and the effect of light, dissolved oxygen andnutrients on their distribution

Two species of Phaeophyceae viz., Padina tetrastromatica and Sargassum vulgare were studied for their seasonal variations in photosynthetic pigments. The pigments such as Chl – a, Chl - c, fucoxanthin and carotenoids were analysed for one year from February 2012 to January 2013. The light was high during November December 2012 and also in January 2013. Disssolved oxygen was high during March to June 2012. Nitrite was high during April to June 2013. Phosphate was high during June to September 2012 and silicate was high during March to June 2012. Of these pigments, Chl – a was with highest content, which was followed by Chl – c, fucoxanthin and carotenoids. The distribution of these pigments varied with the species. P. tetrastromatica showed major peak of Chl – a in February 2012, Chl – c in December 2012, fucoxanthin in August/September 2012 and carotenoids in August and October 2012. Where as, S. vulgare showed major peak of Chl – a, Chl – c and fucoxanthin in August 2012 and carotenoids in May 2012. The ratios of pigments of Chl – c/ Chl – a and fucoxanthin /Chl – a were higher in S. vulgare than in P. tetrastromatica. Significant positive correlation found between carotenoids and fucoxanthin at P > 0.001 level in P. tetrastromatica. Fucoxanthin was positively correlated with dissolved oxygen, nitrite at P > 0.05, Chl –a with Chl – c at P > 0.01 in S. vulgare. The light was positively correlated with pigments in both the species, but not at significant levels. The silicate was negatively correlated with the pigments in both the species of macroalgae.