Study on storage duration of Thalassiosira sp. for shrimp larviculture

Abstract

Storage duration of Thalassiosira sp. paste harvested from partial filtration and flocculation with alum was determined every two weeks. Survival rate of Thalassiosira sp. harvested from filtration decreased after two weeks of storage while that of samples harvested from flocculation was 82.7%, which was not significantly different (p > 0.05) from the control. The total plate counts of samples from filtration and flocculation were in the range of 1.6x105-2.0x106 and 2.8x104-7.0x106 CFU/ml, respectively. Thalassiosira sp. which were harvested and stored at 4°C in the dark for more than two weeks should not be used for scale-up culture since this will affect the quality of samples. Thalassiosira sp. harvested by flocculation could be preserved for six weeks and used as food for shrimp larvae, resulting in a larval survival rate of 78.0 %. On the other hand, Thalassiosira sp. harvested by filtration could be used as shrimp food during the first week of storage only. Thalassiosira sp. stored for at least two weeks will
affect shrimp larval survival rate and length, which both decreased significantly (p < 0.05) compared to that of shrimp larvae fed with fresh phytoplankton.