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Critical thermal minima (CTMin) were determined for subadults of Penaeus merguiensis acclimated at 15, 18, 21 and 24 °C for 3 weeks. The effect of cooling rate on CTMin was also investigated. The CTMin of prawns from these respective acclimation groups were 5.3, 6.0, 7.4, 9.0 and 4.7, 5.4, 6.0, 7.3 °C at the cooling rate of 1 °C h−1 and 3 °C h−1 respectively. Both acclimation temperature and cooling rate had a significant effect (P < 0.01) on the CTMin. Observation during the acclimation period showed that the growth rate of prawns acclimated at 24 °C was much higher than those acclimated at 21, 18 and 15 °C. The results indicate that P. merguiensis can overwinter in aquaculture ponds in south‐east Queensland, Australia, or other subtropical areas and attain good growth if simple overwintering facilities are available.

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More than 500 marine algal strains in Vietnam were screened for their ability to produce high lipids. Among these, a Picochlorum species of Trebuxiophyceae emerged as the species that had the highest total lipid content with a value of 48.6% dry weight (DW), including 27.84% docosahexaenoic acid (DHA). The remaining lipid was mostly C16 and C18 fatty acids, which is appropriate for biofuel production. In addition, 20 different amino acids were identified and included a high ratio of essential amino acids. Subsequently, the effect of environmental conditions for growth, such as salinity, temperature, and media, on the oleogenic potential of this species was investigated. The alga grew better (μ = 0.25 divisions per day) at a salinity of 0.5 M NaCl in enriched seawater medium (MD1) and at high temperature, but the lipid production was higher at 2 M NaCl in artificial medium (MD2) and at low temperature. Consequently, a two‐phase culture system is recommended for obtaining high nutritional lipids and essential amino acids: MD1 can be used for biomass maximization at a high temperature (25°C), and cells can then be transferred into MD2 at a lower temperature (15°C) for oleogenesis.

This 12-month preliminary study investigated the development of sexual characters, primary sexual maturity, ovarian maturity and spawning performance of pond-reared Penaeus merguiensis in relation to culture conditions in south-east Queensland, Australia. Post-larvae of P. merguiensis were produced and cultured in two 60-m 3 tanks during the first 14 weeks. Before winter, they were harvested and stocked in three different overwintering facilities: a 200-m 2 covered pond, two 60-m 3 outdoor tanks and a 15-m 3 indoor, recirculated tank at a stocking density of 10 individuals m À2 . The development of sexual characters was found to be similar to that reported previously in wild P. merguiensis. Males matured at younger ages and smaller sizes than females. Overall, the average size at primary sexual maturity of pond-reared P. merguiensis was 23.1 mm carapace length for males (possessed spermatophores) and 29.3 mm for females (being impregnated). Water temperature and the availability of natural food strongly influenced prawn growth, maturity rate and their subsequent spawning performance. Growth, maturity rate and spawning performance of prawns in the covered pond were significantly higher than in the other overwintering facilities. Prawns started mating at 6±7 months, reached full ovarian maturation and spawned as early as about 8 (peaked at 9±11) months from hatching, producing high fecundity and viable larvae. There was a strong relationship (P , 0.001) between prawn size and fecundity. The results of this study suggest a potential for using pond-reared broodstock P. merguiensis for hatchery production and for domestication or selective breeding programmes.

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This study investigated short‐term effects of increasing water temperature from 27 to 41°C on survival and feed consumption of Penaeus indicus at three different ages: PL25 (postlarvae 25 days old), PL50 and PL90. For each age group, water temperature was maintained at 27°C in the control, but increased to 32, 35, 38 and 41°C at a rate of 1°C every eight hours. The temperature was then kept stable until the end of the 7‐day experiment. Results showed that increasing water temperature affected both survival and feed consumption of the experimental shrimps (p < .01). Survival was highest at 32 and 35°C ranging from 93.8% to 100%, but significantly reduced to 40.0%–81.6% at 38°C. No shrimp survived the 41°C treatment. PL25 were more tolerant to 38–41°C than PL50 and PL90 in terms of survival. Increasing water temperature had no effects on feed consumption of PL25 (p > .05). For PL50 and PL90, feed consumption significantly increased at 38 and 41°C (p < .01) and was similar within the range of 27–35°C. This study suggests that P. indicus in tropical areas can tolerate water temperatures of at least 35°C and should be considered for farming during the summer time.