6 research outputs found
Benthic algae ensure the survival and growth of a detritivorous invertebrate in detritus-based headwater streams
International audienc
Assessment of biomarkers in macrophytes exposed to individual and combined pollutants of agricultural run-off and climate change
International audienc
Regime shifts in freshwater ecosystems exposed to multiple stressors by increasing temperature, fertilizers and pesticides (CLIMSHIFT)
International audienc
Impact of agricultural run-off and climate warming on shallow aquatic ecosystems â possible effects on a regime shift between aquatic primary producers
International audienc
A question of complexity: Investigating regime shifts caused by agricultural run-off and climate warming between aquatic plants and microalgae in micro- and mesocosms
virtuel SciCON meeting due to pandemic Sars-Cov-2International audienc
Disentangling the direct and indirect effects of agricultural runoff on freshwater ecosystems subject to global warming: A microcosm study
International audienceAquatic ecosystems are exposed to multiple stressors such as agricultural run-off (ARO) and climate-change related increase of temperature. We aimed to determine how ARO and the frequency of its input can affect shallow lake ecosystems through direct and indirect effects on primary producers and primary consumers, and whether warming can mitigate or reinforce the impact of ARO. We performed a set of microcosm experiments simulating ARO using a cocktail of three organic pesticides (terbuthylazine, tebuconazole, pirimicarb), copper and nitrate. Two experiments were performed to determine the direct effect of ARO on primary producers (submerged macrophytes, periphyton and phytoplankton) and on the grazing snail Lymnaea stagnalis, respectively. Three different ARO concentrations added as single doses or as multiple pulses at two different temperatures (22°C and 26°C) were applied. In a third experiment, primary producers and consumers were exposed together to allow trophic interactions. When functional groups were exposed alone, ARO had a direct positive effect on phytoplankton and a strong negative effect on L. stagnalis. When exposed together, primary producer responses were contrasting, as the negative effect of ARO on grazers led to an indirect positive effect on periphyton. Periphyton in turn exerted a strong control on phytoplankton, leading to an indirect negative effect of ARO on phytoplankton. Macrophytes showed little response to the stressors. Multiple pulse exposure increased the effect of ARO on L. stagnalis and periphyton when compared with the same quantity of ARO added as a single dose. The increase in temperature had only limited effects. Our results highlight the importance of indirect effects of stressors, here mediated by grazers and periphyton, and the frequency of the ARO input in aquatic ecosystems