Biotic interactions shape the effect of combined stressors on shallow lake ecosystems: insight from microcosms experiments. - Université de Lorraine Access content directly
Conference Papers Year : 2021

Biotic interactions shape the effect of combined stressors on shallow lake ecosystems: insight from microcosms experiments.

Abstract

Organisms living in aquatic ecosystems such as shallow lakes are generally affected by multiple anthropogenic stressors such as pesticides and nitrate input from agricultural runoff or increase in temperature due to global warming. While organisms are affected directly by the stressors, they are also affected indirectly through biotic interactions. The aim of our study was to determine the implication of biotic interactions in the effect of multiple stressors on shallow lake ecosystems. We performed a set of microcosm experiments in which organisms were exposed to a cocktail of organic pesticides, copper and nitrate to simulate agricultural runoff. Different scenario of pollutant input, as one or several pulses, were used. A 4°C warming was also used to simulate the impact of global warming. Two separate experiments were performed to determine the direct effect of on a primary producer community (submerged macrophytes, periphyton and phytoplankton) and on a primary consumer, the benthivorous snail Lymnaea stagnalis. In a third experiment, primary producers and three different primary consumers (Daphnia, mussel, snail) were exposed together to allow trophic interactions. When primary producers and consumers were exposed separately, agricultural runoff had a direct positive effect on phytoplankton and a strong negative effect on L. stagnalis. When exposed together, phytoplankton showed in contrast a significant decrease. Using structural equation modelling, we determined that this effect on phytoplankton was not a direct effect of the agricultural runoff but an indirect effect. Indeed, inhibition of L. stagnalis grazing on periphyton induced a positive effect of agricultural runoff on periphyton, while periphyton reduced the development of phytoplankton through competitive interactions. This demonstrates the importance of taking into account biotic interactions to understand the effect of multiples stressors on shallow lake ecosystems.
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Dates and versions

hal-03930069 , version 1 (09-01-2023)

Identifiers

  • HAL Id : hal-03930069 , version 1

Cite

Joey Allen, Elisabeth M. Gross, Camille Courcoul, Stéphanie Bouletreau, Arthur Compin, et al.. Biotic interactions shape the effect of combined stressors on shallow lake ecosystems: insight from microcosms experiments.. 10th International Shalow Lakes Conference, Mar 2021, Natal (Virtuel), Brazil. ⟨hal-03930069⟩
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