Growth rate and carrageenan yield of Kappaphycus alvarezii (Rhodophyta, Gigartinales) cultivated in Kolambugan, Lanao del Norte, Mindanao, Philippines

The growth and carrageenan content of Kappaphycus alvarezii (Doty) Doty ex Silva (brown strain) cultivated in four coastal barangays of Kolambugan, Lanao del Norte namely; Barangay Manga, Simbuco, Tabigue and Mukas were determined for a period of 12 months. Some environmental parameters were also obtained: water temperature, salinity, water flow and inorganic phosphate and nitrate. Results showed great variability in growth rate and carrageenan content with sampling periods and sites. Higher growth rate and carrageenan yield occurred during the southwest monsoon from June to September, and lower growth rate occurred during the northwest monsoon from October to May in all of the sampling sites. Multiple stepwise regression analysis showed that water temperature and salinity were the environmental factors that affect growth and carrageenan yield in all of the sampling sites. Maximum growth and carrageenan yield were obtained during the southwest monsoon (June - September) when water temperature and salinity was at the range of 280C – 310C and 24‰ - 30‰, respectively. Based on the present study, it can be seen that there is a potential for K. alvarezii cultivation in Kolambugan, Lanao del Norte since the growth and carrageenan yield were within the commercial requirement desirable for commercial crops. The seasonal variations in growth rate and carrageenan yield can be related to seawater temperature and salinity. Water flow and inorganic phosphate were the other factors that can influence carrageenan yield.