Cultures of six benthic diatoms were maintained in the dark to measure their viability and biochemical composition after 8 wk of storage at low temperature (4 C) in darkness by refrigeration. Cell density, growth rate, and viability for each benthic diatom changed significantly after storage. Significant differences were observed with regard to cell size (length and width) of Nitzschia laevis, Navicula sp., and Amphora tenerrima as a result of storage. In general, the proximal composition of the benthic diatom cultures changed after week 1 of storage and decreased after week 4 of storage for all the diatoms. These results demonstrate that under 1-4 wk of storage these diatoms maintain their viability and had changes in their proximal composition in species-specific responses. Storage of preserved live microalgae cells is an alternative technique that can be used to reduce the need for continuous maintenance of live cultures and can provide live feed stock for aquaculture applications.

We determined the effects of 16 wk of storage at low temperature (4 C) in darkness on the viability, growth, photosynthetic parameters, and biochemical composition of four diatom cultures. Significant differences in cell density and proximal composition were observed for all diatoms throughout storage. Cell density increased with time of storage for all diatoms. Protein content increased for Navicula incerta, Nitzschia laevis, and Navicula sp., whereas lipid content increased during storage in only N. incerta. When the stored diatoms were used as inocula in fresh medium, they increased their viability, generating a lag phase for Nitzschia thermalis var. minor, N. incerta, and Navicula sp. cultures. There were noted species‐specific modifications in proximal composition, ash‐free dry weight, and photosynthetic parameters in response to storage. We conclude that N. thermalis, N. incerta, N. laevis, and Navicula sp. can be stored at 4 C for 16 wk and are viable in new cultures.

We measured the proximal composition of four benthic diatoms that were stored for 24 mo in the dark at low temperature (4 C by refrigeration) and examined their potential as feed for abalone, Haliotis rufescens, postlarvae. The proximal composition of the four diatoms was modified by species-specific responses as a function of time in storage. The cultures of all stored diatoms contained low or undetectable concentrations of Vibrio-like bacteria (<0.01 VLB/mL). As feed for abalone postlarvae, the four diatoms promoted growth under all experimental conditions. Greater shell lengths were measured on Day 14 when Navicula sp. and Navicula incerta were used as feed. Postlarvae that were fed N. incerta and Navicula sp. had higher growth rates. In contrast, lower growth rates were observed on Day 7 with fresh and stored Nitzschia thermalis as food. Survival was high in postlarvae that were fed the four stored diatoms (100%). This report demonstrates that cultures of benthic diatoms that have been stored by refrigeration for 24 mo can be used to feed abalone postlarvae and have an effect on improving growth and survival.