36 JUNE 2015 • WORLD AQUACULTURE • WWW.WAS.ORG data on the effects of salinity and temperature on algal growth were analyzed using repeated measures ANOVA using SAS statistical software. What We Found To the best of our knowledge, this was the first attempt to isolate and culture microalgae strains from Indonesia, particularly South East Sulawesi. We isolated four diatom strains in this study (Figs. 4 and 5) denoted as Kb1-3, Kb1-2, Kb1-5 and Kb2-6 and identified as Melosira moniliformis. Furthermore, we obtained the cell size of all strains of microalgae cultured in this study (Table 1). The cell size and shapes of strains Kb1-3, Kb1-2 and Kb1-5 are comparable to T. weissflogii, which is considered to be a suitable size for shrimp during early larval stages (Nunez et al. 2002, Kent et al. 2011, Ferreira et al. 2012). We plan to conduct feeding trials with larval shrimp using these newly isolated strains. Growth of Local Isolates. Growth experiment on South East Sulawesi strains of microalgae indicated that growth rates were similar to strains currently used in aquaculture hatcheries (Fig. 6). What We Surmise and Future Directions The rapid doubling time of population growth was achieved at the same number of days of culture for almost all strains of microalgae (Fig. 6), with no initial lag in growth except for Kb1-5, C. neogracile and T. weissflogii cultured at 30 psu , T. lutea at 25 and 35 psu and C. neogracile at 35 psu. On average, all strains doubled their cells once daily durng the rapid (log phase) growth period, with the rate decreasing after eight days. The growth of Kb1-5 and Kb1-2 was greater at 25 and 30 psu during the log phase in comparison to other strains. These local isolates grew at the same rate as other microalgae that have been extensively used in aquaculture. However, growth rate is not the only factor to consider in selecting good candidates for aquaculture. Biomass of microalgae must also be carefully assessed in live food production. In this study, although Kb1-5 grows well at 35 psu, the biomass produced during the end of log phase is less than Kb1-2, Kb1-3 and M. moniliformis (Fig. 5). Cultures of Indonesian strains that resulted in high biomass, similar to T. lutea, C. neogracile and T. weissflogii, particularly at 35 psu, were Kb1-2 and Kb1-3. All Indonesian strains grew well at high salinity (30-35 psu), indicating that high salinities may be preferred by those strains. Salinity preference is species-specific in microalgae (Gu et al. 2012), although diatoms can tolerate a wide range of salinity, considering their ability to inhabit various habitats from freshwater to marine environment. TOP, FIGURE 4. Kb2-6 that was identified as M. moniliformis. BOTTOM, FIGURE 5. Kb1-2 that is most probably a strain of Chaetoceros.
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