Techniques on algae harvesting and preservation for use in culture and as larval food

Abstract

A method of algae harvesting and preservation was developed. Test algal species consisted of two diatoms: Chaetoceros calcitrans and Skeletonema costatum, and two flagellates: Tetraselmis chui and Isochrysis galbana. Chemical flocculation using alum and lime were evaluated as methods of harvesting algae. Freezing and sun-drying were used as methods of preservation with viability tests done on frozen samples. The usefulness of sun-dried algae was evaluated through its ability to support survival of Penaeus menodon larvae. Results showed that alum and lime flocculation were effective for Chaetoceros, Tetraselmis and Skeletonema but ineffective for Isochrysis. Optimum pH for algae removal with alum was found to be 6.5. With lime, algae removals increased with pH and was optimum at pH 9.5. A simple freezing technique preserves the viability of algal concentrates for culture purposes. Good performance of sun-dried Chaetoceros and Tetraselnlis suggests that these algae may be used as larval feed for Penaens monodon alone or supplementarily to eliminate complete dependence on carefully-timed live algal production.