Growth rate and carrageenan yield of Kappaphycus alvarezii in a land-based setup using artificial seawater

Abstract

Kappaphycus alvarezii is among the most significant tropical red algae commercially cultivated for its economic significance due to the kappa-carrageenan. It is used for multiple products and applications such as gelling, thickening, and stabilizing water-binding  agents, and texturing a variety of dairy-based and instant products. With the rising demands and associated farm problems, seaweed farms need alternative cultivation techniques to boost seed stock quality. The percent growth rate and carrageenan yield of a land-based cultivated K. alvarezii collected from Calatagan, Batangas were determined for 30 days under optimum salinity (30-31 ppt) and temperature (29-31°C). One 5 g seedling of K. alvarezii was placed in each of the twelve aquariums (12 x 6 x 8 in) having 5.6 L of four different media (seawater, Blue Treasure salt, Coral Pro Salt and rock salt). Results showed that the higher percent growth rate in seawater and Blue Treasure salt did not differ significantly (4.58 ± 0.51 % day-1 and 3.94±0.39 %day-1, respectively). In addition, the carrageenan yield in Blue Treasure salt (37.75 ± 3.03%) was significantly higher than seawater (18.06 ± 1.23%) but both meet the industrially required carrageenan yield. On the other hand, lower percent growth rate was observed in Coral Pro Salt while seedlings disintegrate in rock salt after a week. The study suggests that Blue Treasure salt can be an alternative medium for growing K. alvarezii in land-based cultivation under optimum salinity and temperature.