Fostering integration of freshwater ecology with ecotoxicology

Abstract

SUMMARY1. Ecology and ecotoxicology have different historical roots, despite their similar names, but are slowly converging to meet the challenge of addressing the massive global proliferation and release of chemicals in the environment. The conceptual, methodological, review and standard research papers in this special issue reflect this emerging trend of blending ecological and ecotoxicological perspectives to assess impacts in freshwater ecosystems. 2. Assessing community and ecosystem impacts of chemical contaminants is complex, however, and will require approaches that explicitly consider biological and chemical diversity as well as the natural variability of environmental factors at multiple spatial and temporal scales. 3. Central themes of the papers in this issue are (i) the importance of indirect effects of chemical contaminants on species interactions and food webs; (ii) effects of multiple stressors, especially interactions between contaminants and environmental factors; (iii) consequences of chemical exposure on ecosystem processes such as primary production and litter decomposition; (iv) the need to account for context dependency and (v) potentially harmful community and ecosystem effects of emerging contaminants, among which nanoparticles are prominently represented. 4. Collectively, these papers show that integrating ecological principles into the design and implementation of ecotoxicological research is essential for assessing and predicting contaminant impacts on biological communities and ecosystems. Conversely, applied ecology and bioassessment would benefit from concepts and approaches developed in ecotoxicology and from fully embracing chemical contaminants as key drivers of community structure and ecosystem processes.

Chlorpyrifos interacts with other agricultural stressors to alter stream communities in laboratory microcosms

“…Our observations are consistent with a growing body of research highlighting the importance of considering multiple‐stressor interactions, and indirect effects on ecosystem processes, when evaluating the impacts of organic toxicants on freshwater ecosystems (Alexander et al. , Gessner and Tlili , Schäfer et al. ).…”

Synthetic chemicals as agents of global change

“…; Rosi‐Marshall and Royer ; Halstead et al . ; Gessner and Tlili ). Third, many synthetic chemicals are persistent or pseudo‐persistent in the environment, with their ecological and, indeed, their evolutionary consequences likely to persist long after their release.…”

Pressure-Induced Shifts in Trophic Linkages in a Simplified Aquatic Food Web

“…This suggests that there are qualitatively different effects of stressors on the different functional parts (green and brown) of the food web. This may have strong implications for our understanding of the effects of pesticides and nutrients on key ecosystem processes (Gessner and Tlili, 2016). However, the observed strong interactions between different pesticide classes and nutrients for the different parts of the aquatic food web also present us with a puzzle: we have no clear explanations for the second and third-order effects that go beyond mere speculation.…”

“…To date, the vast majority of studies focusing on the effect of pesticides have evaluated the effect of a single chemical substance on survival of individuals, as this is the common approach in ecotoxicological risk assessment (van den Brink, 2006;Gessner and Tlili, 2016). Most ecosystems however, particularly aquatic ecosystems bordering agricultural land, are exposed to a myriad of interacting stressors (Ormerod et al, 2010;Gagic et al, 2017), making it important to predict their direct and indirect effects on networks of trophic linkages.…”