Growth rate and carrageenan yield of cultivated Kappaphycus alvarezii (Doty) Doty in the coastal waters of Bay of Bengal at Chepala Timmapuram, Andhra Pradesh, east coast of India

Experimental field cultivation of Kappaphycus alvarezii was done successfully in the coastal waters of Bay of Bengal at Chepala Timmapuram, Visakhapatnam district, Andhra Pradesh, east coast of India from March 2015 to December 2015 to evaluate its economic feasibility of cultivation. Two methods were adopted for cultivation viz., tubular method and netbag method. In both the methods, 20 lines of 60 m each were floated. Data on crop yield, daily growth rate, carrageenan yield, and its gel strength were collected after 45-day growth cycle. The mean crop yields of 270.20 +/- 20.61 kg fresh weight (FW) per line and 301.15 +/- 30.81 kg FW per line were obtained in tubular and netbag methods, respectively, with respective mean growth rates of 3.34 +/- 0.17 and 3.57 +/- 0.23%. The mean carrageenan (semi refined carrageenan) yields were found to be 33.33 +/- 1.12 and 30.36 +/- 1.00% in tubular and netbag methods, respectively, with respective mean gel strength of 404.09 +/- 24.80 and 362.50 +/- 26.43 g cm(-2). The growth rates and the quantity and quality of carrageenan obtained in this study were comparable with the ones obtained elsewhere. The physical (temperature and salinity) and chemical (nitrate and phosphate) parameters of the seawater were found to be very conducive for the growth of this seaweed. Pearson's correlation coefficient (r) at 0.05 level showed a significant positive correlation between DGR and seawater temperature (r = 0.557) and DGR and salinity (r = 0.541) in tubular method only. Further, a significant positive correlation was seen between carrageenan and temperature (r = 0.636), carrageenan and salinity (r = 0.882), and carrageenan and phosphate (r = 0.538) in tubular method, whereas a significant negative correlation was seen between carrageenan and salinity (r = -0.514) in netbag method. However, seawater temperature showed significant positive correlation with salinity (r = 0.731) and also with nitrate (r = 0.646). Salinity showed significant positive correlation with phosphate (r = 0.609). This study would encourage commercial field cultivation to be carried out by the coastal people in Andhra Pradesh. Each farmer could earn an average monthly income of Rs 19,128 (US$290) to 21,945 (US$333) by adopting Kappaphycus cultivation.