EFFECTS OF TEMPERATURE AND DISSOLVED OXYGEN CONCENTRATION ON LIFE HISTORY OF THE FRESHWATER CLADOCERAN Moina macrocopa

The freshwater cladocerans of the genus Moina live in pools, small ponds and rice paddies, and are resistant to poor water quality, extreme temperatures and hypoxia. The ability of Moina to survive in harsh conditions makes them suitable for use as live food for many species of newly hatched freshwater fish. In some Southeast Asian countries, Moina is mass cultured in shallow ponds fertilized with chicken manure. However, scientific information on the life history of Moina is scarce. This study examines the combined effects of temperature and dissolved oxygen concentration (DO) on the survivorship, growth and reproduction of Moina macrocopa.

High temperature reduced the lifespan of M. macrocopa. Average lifespan was ~18.9 days at 18°C, ~ 11 days at 25°C and < 5 days at 35°C. The average number of young per female was much lower at 35°C than at 18 and 25°C, because females produced fewer and much smaller broods during their shorter lifespans at 35°C. M. macrocopa displayed high tolerance to low DO condition. The effects of DO concentration on the life history parameters of M. macrocopa could not be evaluated at 18°C, but lifespan and reproductive performance parameters such as brood size, number of broods produced and number of young produced were not affected by DO concentration at both 25 and 35°C. Results presented here indicate that while M. macrocopa is tolerant to hypoxic conditions, high temperatures commonly encountered in its natural habitats in subtropical Southeast Asia may adversely affect its survivorship and reproductive performance