Experimental farming of Kappaphycus alvarezii (Doty) Doty with income estimates at different sites in the Mandapam region, Palk Bay, southeast coast of India

Abstract

The cultivation of Kappaphycus alvarezii, a kappa carrageenan producing red seaweed, was done for 1 year from April 2012 to March 2013 in subtropical waters of Indian Peninsula at three different sites (Mangadu in Rameswaram Island, Munaikadu and Vedalai—on main land coast) on Palk Bay side of Bay of Bengal of Rameswaram–Mandapam region of southeast coast of India. These experiments were carried out to confirm the results obtained in an earlier study (April 2011 to March 2012) at more or less the same sites—one is different (Mangadu) and two are the same (Munaikadu and Vedalai). The maximum crop yields of 326.55 ± 10.23 and 316.65 ± 15.13 kg FW raft−1 were obtained in October 2012 at Mangadu and Munaikadu, respectively, and 308.40 ± 8.89 kg FW raft−1 in March 2013 at Vedalai. Similarly the maximum daily growth rates (DGRs) of 3.76 ± 0.07 and 3.69 ± 0.11 % were found in October 2012 at Mangadu and Munaikadu, and 3.64 ± 0.06 % was obtained in March 2013 at Vedalai. A significant negative correlation between DGR and seawater temperature at Mangadu (r = −0.604) and Munaikadu (r = −0.700) was found (at 0.05 level). Further, a significant positive correlation was seen (at 0.05 level) between nitrite and phosphate at Mangadu (r = +0.613) and Vedalai (r = +0.599). However, salinity and seawater temperature were significantly positively correlated (r = +0.693) at Munaikadu (at 0.05 level). ANOVA showed that the growth rates among these three sites were found to be statistically insignificant. Tip grazing by Siganus javus and Diodon holocanthus during the monsoon period (October 2012 to January 2013) was observed. Seasonal epiphytes Lyngbya majuscula and Cladophora facsicularis were the main problematic epiphytes from April to June. Net income would be Rs15,000 to Rs16,000 (US$250–US$265) per month, and if the cultivation is taken up in earnest perspective, the farmers would improve their living standards.