Combined effects of light pollution and the insecticide malathion on the freshwater crustacean Daphnia magna

Details

Supervisors

Eli, Thoré

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

enFreshwater ecosystems are increasingly exposed to multiple anthropogenic stressors, including chemical pollution and artificial light at night (ALAN). Although their individual effects on aquatic organisms are well documented, their combined impacts remain poorly understood. In this study, we investigated the individual and combined effects of the organophosphorus insecticide malathion and ALAN on the freshwater cladoceran Daphnia magna. An acute toxicity test (48 h) and a sub-chronic exposure (15 days) were conducted under natural lightdark cycles or with artificial light during the night. Endpoints included immobilization, morphology, life-history traits, and swimming behaviour. Malathion toxicity was reduced under light exposure in the acute test, likely reflecting changes in pollutant availability. In the subchronic experiment, ALAN affected growth, eye morphology, and reproduction, whereas malathion showed limited effects at the tested concentration. These results highlight the importance of considering multiple stressors when assessing ecological risks in freshwater environments.