Disentangling the direct and indirect effects of agricultural runoff on freshwater ecosystems subject to global warming: A microcosm study

Aquatic ecosystems are exposed to multiple stressors such as agricultural run-off (ARO) and climate-change related increase of temperature. We aimed determine how ARO the frequency its input can affect shallow lake through direct indirect effects on primary producers consumers, whether warming mitigate or reinforce impact ARO. performed a set microcosm experiments simulating using cocktail three organic pesticides (terbuthylazine, tebuconazole, pirimicarb), copper nitrate. Two were effect (submerged macrophytes, periphyton phytoplankton) grazing snail Lymnaea stagnalis, respectively. Three different concentrations added single doses pulses at two temperatures (22°C 26°C) applied. In third experiment, consumers together allow trophic interactions. When functional groups alone, had positive phytoplankton strong negative L. stagnalis. together, producer responses contrasting, grazers led an periphyton. Periphyton in turn exerted control phytoplankton, leading phytoplankton. Macrophytes showed little response stressors. Multiple pulse exposure increased stagnalis when compared with same quantity dose. The temperature only limited effects. Our results highlight importance stressors, here mediated by periphyton, aquatic ecosystems.