Seasonal variation in growth and carrageenan yield in cultivated Kappaphycus alvarezii (Doty) Doty on the coastal waters of Ramanathapuram district, Tamil Nadu

Kappaphycus alvarezii, a kappa carrageenan yielding red seaweed, was cultivated in Indian subtropical waters on the Palk Bay side of Bay of Bengal in Ramanathapuram district, Tamil Nadu, at three different sites: Vedalai, Munaikadu, and Thonithurai, for 1 year from April 2011 to March 2012. The maximum crop yields of 416 +/- 51 and 550 +/- 41 FW raft(-1) were recorded at Vedalai and Munaikadu, respectively, in December 2011, whereas a maximum of 326 +/- 49 FW raft(-1) was recorded at Thonithurai in April 2011. Similarly, the maximum daily growth rates (DGRs) of 4.30 +/- 0.51 % and 4.92 +/- 0.40 % were obtained at Vedalai and Munaikadu, respectively, in December 2011, and 3.76 +/- 0.48 % was recorded at Thonithurai in April 2011. Variations in environmental parameters like seawater temperature, salinity, nitrate, and phosphate were found to influence the growth of the seaweed. The maximum carrageenan content as a percentage of dry weight was 29.30 +/- 0.61 % (Vedalai), 31.00 +/- 0.71 % (Munaikadu), and 29.10 +/- 1.12 % (Thonithurai) in March 2012. The data on moisture content (%), clean anhydrous weed/salt ratio, and carrageenan yield obtained in this study fulfilled those of international standards. Further, the results indicated that large-scale cultivation by either NGOs or self-help groups (SHGs) may be taken up along the coastal waters for the benefit of the poverty-stricken coastal people as their livelihood, as the growth rate obtained in this study compared well with that recommended for commercial cultivation elsewhere.