UV radiation affects antipredatory defense traits in Daphnia pulex

• Published in: Ecology and evolution Vol. 10; no. 24; pp. 14082 - 14097
• Main Authors: Eshun‐Wilson, Franceen, Wolf, Raoul, Andersen, Tom, Hessen, Dag O., Sperfeld, Erik
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.12.2020; John Wiley and Sons Inc; Wiley
• Subjects: Algae; aquatic ecosystem; Aquatic environment; Bayesian statistics; Body length; Chaoborus; Chemical stimuli; Community composition; Daphnia pulex; Deactivation; Defense; Ecological effects; Endangered & extinct species; Exposure; Food chains; Food composition; Food webs; Invertebrates; Juveniles; Kairomone; Kairomones; Larvae; MCMC chains; Morphology; Organisms; Original Research; phenotypic plasticity; Predation; Predators; predator–prey interaction; Prey; Shallow water; Spine; Ultraviolet radiation; UV‐A; zooplankton; Norway; Chaoborus; MCMC chains; aquatic ecosystem; Bayesian statistics; predator–prey interaction; zooplankton; UV‐A; phenotypic plasticity; Kairomone
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6999

In aquatic environments, prey perceive predator threats by chemical cues called kairomones, which can induce changes in their morphology, life histories, and behavior. Predator‐induced defenses have allowed for prey, such as Daphnia pulex, to avert capture by common invertebrate predators, such as Chaoborus sp. larvae. However, the influence of additional stressors, such as ultraviolet radiation (UVR), on the Daphnia–Chaoborus interaction is not settled as UVR may for instance deactivate the kairomone. In laboratory experiments, we investigated the combined effect of kairomones and UVR at ecologically relevant levels on induced morphological defenses of two D. pulex clones. We found that kairomones were not deactivated by UVR exposure. Instead, UVR exposure suppressed induced morphological defense traits of D. pulex juveniles under predation threat by generally decreasing the number of neckteeth and especially by decreasing the size of the pedestal beneath the neckteeth. UVR exposure also decreased the body length, body width, and tail spine length of juveniles, likely additionally increasing the vulnerability to Chaoborus predation. Our results suggest potential detrimental effects on fitness and survival of D. pulex subject to UVR stress, with consequences on community composition and food web structure in clear and shallow water bodies. In aquatic environments, prey perceive predator threats by chemical cues called kairomones, which can induce changes in their morphology, life histories, and behavior. Predator‐induced defenses have allowed for prey, such as Daphnia pulex, to avert capture by common invertebrate predators, such as Chaoborus sp. larvae. The influence of additional stressors, such as ultraviolet radiation (UVR), on the Daphnia–Chaoborus interaction is not settled as UVR may deactivate the kairomone. In laboratory experiments, we investigated the combined effect of kairomones and UVR at ecologically relevant levels on induced morphological defenses of two D. pulex clones. We found that kairomones were not deactivated by UVR exposure. Instead, UVR exposure suppressed induced morphological defense traits of D. pulex juveniles under predation threat by generally decreasing the number of neckteeth and especially by decreasing the size of the pedestal beneath the neckteeth.