Caloric content of Daphnia magna as reflect of propanil stress during a short-term exposure and its relationship to long-term responses

The present study investigates energy stores changes in the aquatic invertebrate Daphnia magna following a 5-d exposure to propanil. Juveniles of D. magna were exposed to sublethal propanil concentrations (0.07, 0.10, 0.21 and 0.55 mg l−1) which were used previously to test their effect on reproduction, growth and survival (21 days test) of D. magna. Glycogen, total lipids, proteins, and dry weight were determined in control and exposed daphnids at 24, 48, 72, 96 and 120 h. Data were used to calculate caloric content as biomarker of propanil exposure. Results showed a depletion of energy reserves in D. magna exposed to the herbicide. At 120 h of exposure to the highest propanil concentration (0.5 mg l−1), the reduction in daphnid reserves were glycogen (28%), proteins (28%) and lipids (31%), and caloric content was reduced in 27%. On the other hand, we found a positive correlation between caloric content and the chronic parameters intrinsic rate of natural increase and offspring per female when daphnids were exposed for 120 h to the herbicide.

► We investigated the effect of propanil in the caloric content of Daphnia magna.
► We investigated the correlation between chronic effects and caloric content.
► Caloric content (120 h) correlated positively to time and inversely to concentration.
► Caloric content (120 h) correlated to offspring per female (21 d).
► Caloric content (120 h) correlated to the intrinsic rate of natural increase (21 d).