title: Competition matters: species interactions prolong the long-term effects of pulsed toxicant stress on populations.
abstract: Recent empirical studies have revealed the importance of species competition for the effects of toxicants on populations. In the present study, the authors applied a generic individual-based simulation model of 2 competing species to analyze the consequences of interspecific competition for population dynamics under pulsed contamination. The results indicated that competition that causes a density-dependent decrease in reproduction can substantially prolong the long-term effects of the toxicant. In the example investigated, population recovery time increased from approximately 1 generation time without competition to more than 3 generation times under competition. In particular, species with low reproductive capacity exhibited a strongly prolonged recovery time when interspecific competition was included in the model. The authors conclude that toxicant concentrations derived from risk assessments for pesticides that do not consider competition might be under-protective for populations in real-world systems. The consideration of competition is especially relevant for species with low reproductive capacities to enable a realistic estimation of recovery pace.
authors.affiliation: Department of System-Ecotoxicology, Helmholtz Centre for Environmental Research, Leipzig, Germany; Department of System Analysis, Integrated Assessment and Modelling, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
authors.forename: Mira
authors.initials: M
authors.lastname: Kattwinkel
authors.forename: Matthias
authors.initials: M
authors.lastname: Liess
mesh_terms: D000818:Animals; D003163:Competitive Behavior; D003198:Computer Simulation; D003621:Daphnia / Q000187:drug effects* / Q000502:physiology*; D004785:Environmental Pollutants / Q000633:toxicity*; D008954:Models, Biological; D010575:Pesticides / Q000633:toxicity*; D011157:Population Dynamics; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D010575:Pesticides
keywords: Agent-based model; Ecological risk assessment; Ecotoxicology; Individual-based model; Population modeling