The influence of feeding, photoperiod and selected solvents on the reproductive strategies of the water flea, Daphnia magna

• Published in: Environmental pollution (1987) 2000-12, Vol.110 (3), p.425-430
• Main Authors: ZHANG, L, BAER, K. N
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Daphnia magna; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Fundamental and applied biological sciences. Psychology
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/S0269-7491(99)00324-3

The influence of different feeding rates, reduced photoperiod and ethanol and acetone exposure on male production in Daphnia magna was investigated. Male production was observed under reduced photoperiod (8-h light:16-h dark) in all food levels. However, the sex ratio of daphnids fed 1x10(6) algae cells increased significantly from that of daphnids fed 15x10(6) algae cells (0.486+/-0.059 and 0.271+/-0.027, respectively). Under normal photoperiod (16-h light:8-h dark) and low food conditions (3.75x10(6) algae cells), a statistically significant increase in the sex ratio was observed in daphnids exposed to acetone at EPA acceptable solvent limits (0.1 ml/l). A shift back to parthenogenetic reproduction was observed in acetone-exposed daphnids at high food levels (15x10(6) algae cells). The results indicate that the reproductive strategies of females are influenced by phenological (i.e. reduced photoperiod), dietary and exogenous chemical cues.