Species interactions and chemical stress: Combined effects of intraspecific and interspecific interactions and pyrene on Daphnia magna population dynamics

• Published in: Environmental toxicology and chemistry 2015-08, Vol.34 (8), p.1751-1759
• Main Authors: Viaene, Karel P. J., De Laender, Frederik, Rico, Andreu, Van den Brink, Paul J., Di Guardo, Antonio, Morselli, Melissa, Janssen, Colin R.
• Format: Article
• Language: English
• Subjects: Animal behavior; Animal populations; Animals; Aquatic populations; Chaoborus; Chemical effects; Competition; Crustaceans; Daphnia - drug effects; Daphnia - growth & development; Daphnia magna; Diptera - drug effects; Diptera - growth & development; Dynamics; Ecological risk assessment; Exposure; Generalized linear models; Interspecific relationships; Larva - drug effects; Larva - growth & development; Larvae; Mathematical models; Nonnative species; Polycyclic aromatic hydrocarbons; Population; Population Density; Population Dynamics; Population number; Population structure; Population studies; Predation; Predatory Behavior - drug effects; Pyrene; Pyrenes; Pyrenes - chemistry; Pyrenes - toxicity; Risk Assessment; Species interactions; Statistical models; Toxicity Tests; Toxicology
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1002/etc.2973

Species interactions are often suggested as an important factor when assessing the effects of chemicals on higher levels of biological organization. Nevertheless, the contribution of intraspecific and interspecific interactions to chemical effects on populations is often overlooked. In the present study, Daphnia magna populations were initiated with different levels of intraspecific competition, interspecific competition, and predation and exposed to pyrene pulses. Generalized linear models were used to test which of these factors significantly explained population size and structure at different time points. Pyrene had a negative effect on total population densities, with effects being more pronounced on smaller D. magna individuals. Among all species interactions tested, predation had the largest negative effect on population densities. Predation and high initial intraspecific competition were shown to interact antagonistically with pyrene exposure. This was attributed to differences in population structure before pyrene exposure and pyrene‐induced reductions in predation pressure by Chaoborus sp. larvae. The present study provides empirical evidence that species interactions within and between populations can alter the response of aquatic populations to chemical exposure. Therefore, such interactions are important factors to be considered in ecological risk assessments. Environ Toxicol Chem 2015;34:1751–1759. © 2015 SETAC