Predictability of the impact of multiple stressors on the keystone species Daphnia

Abstract

Eutrophication and climate change are two of the most pressing environmental issues affecting up to 50% of aquatic ecosystems worldwide. Mitigation strategies to reduce the impact of environmental change are complicated by inherent difficulties of predicting the long-term impact of multiple stressors on natural populations. Here, we investigated the impact of temperature, food levels and carbamate insecticides, in isolation and in combination, on current and historical populations of the freshwater grazer Daphnia. We used common garden and competition experiments on historical and modern populations of D. magna ‘resurrected’ from a lake with known history of anthropogenic eutrophication and documented increase in ambient temperature over time. We found that these populations response dramatically differed between single and multiple stressors. Whereas warming alone induced similar responses among populations, warming combined with insecticides or food limitation resulted in significantly lower fitness in the population historically exposed to pesticides. These results suggest that the negative effect of historical pesticide exposure is magnified in the presence of warming, supporting the hypothesis of synergism between chemical pollution and other stressors.

Global lake responses to climate change

“…Human impacts on terrestrial nutrient cycles are among the most prevalent interacting factors, and the combination of increases in both nutrient inputs and temperature could be syner gistic, leading to hypoxic conditions and influencing community structure and biodiversity 165,166 and the fre quency, intensity, extent and duration of harmful algal blooms 138,167 . Negative effects of legacy conditions can be magnified in the presence of warming, supporting proposed synergisms between chemical pollution and other stressors 168 . Lake responses are not necessarily regionally synchronous, as morphometric character istics are known to drive trajectories of warming 10 and ice loss 7 , and lake depth has also been linked to commu nity responses 163 .…”

Roundup causes embryonic development failure and alters metabolic pathways and gut microbiota functionality in non-target species

“…1 ). We used three genotypes hatched from dormant Daphnia embryos revived from Lake Ring, Denmark: LRV3.5_15, LRV13.5_1 and LRV13_2 [ 26 , 28 , 29 ]. We also used a laboratory reference strain, P-IT, provided by the Institute of Ecosystem study, CNR Verbania, Italy.…”

“…The impact of glyphosate and of its commercial formula Roundup (Bayer) were quantified on D. magna by measuring changes in fitness-linked life history traits, genome-wide transcription, and the microbiota. Four genotypes were used: LRV3.5_15, LRV13.5_1 and LRV13_2 were previously isolated from a shallow lake in Denmark [ 26 , 28 , 29 ]; P-IT is a laboratory reference strain provided by the Institute of Ecosystem study, CNR Verbania, Italy. Host response was measured in multiple fitness-linked life history traits and at genome-wide transcriptional level.…”

How Do Indirect Effects of Contaminants Inform Ecotoxicology? A Review

“…This increased light stimulated benthic microalgae, increasing the food supply for benthic animals, which unexpectedly led to higher densities in heavily oiled compared to unoiled marshes [78,79]. Finally, interactions between chemical contaminants and climate change will likely reveal many indirect effects on contaminant dispersion and bioavailability as well as ecosystem function [80][81][82][83][84].…”