title: Temporal constraints on predation risk assessment in a changing world.
abstract: Habitat degradation takes various forms and likely represents the most significant threat to our global biodiversity. Recently, we have seen considerable attention paid to increasing global CO2 emissions which lead to ocean acidification (OA). Other stressors, such as changing levels of ultraviolet radiation (UVR), also impact biodiversity but have received much less attention in the recent past. Here we examine fundamental questions about temporal aspects of risk assessment by coral reef damselfish and provide critical insights into how OA and UVR influence this assessment. Chemical cues released during a predator attack provide a rich source of information that other prey animals use to mediate their risk of predation and are the basis of the majority of trait-mediated indirect interactions in aquatic communities. However, we have surprisingly limited information about temporal aspects of risk assessment because we lack knowledge about how long chemical cues persist after they are released into the environment. Here, we showed that under ambient CO2 conditions (~385 μatm), alarm cues of ambon damselfish (Pomacentrus amboinensis) did not degrade within 30 min in the absence of ultraviolet radiation (UVR), but were degraded within 15 min when the CO2 was increased to ~905 μatm. In experiments that used filters to eliminate UVR, we found minimal degradation of alarm cues within 30 min, whereas under ambient UVR conditions, alarm cues were completely degraded within 15 min. Moreover, in the presence of both UVR and elevated CO2, alarm cues were broken down within 5 min. Our results highlight that alarm cues degrade surprisingly quickly under natural conditions and that anthropogenic changes have the potential to dramatically change rates of cue degradation in the wild. This has considerable implications for risk assessment and consequently the importance of trait-mediated indirect interactions in coral-reef communities.
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada. Electronic address: doug.chivers@usask.ca.
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Chivers
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville Qld4811, Australia; School of Marine and Tropical Biology, James Cook University, Townsville Qld4811, Australia.
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Ramasamy
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville Qld4811, Australia; School of Marine and Tropical Biology, James Cook University, Townsville Qld4811, Australia.
authors.forename: Mark I
authors.initials: MI
authors.lastname: McCormick
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville Qld4811, Australia; School of Marine and Tropical Biology, James Cook University, Townsville Qld4811, Australia.
authors.forename: Sue-Ann
authors.initials: SA
authors.lastname: Watson
authors.affiliation: School of Biomedical Sciences, University of Queensland, Brisbane Qld4072, Australia.
authors.forename: Ulrike E
authors.initials: UE
authors.lastname: Siebeck
authors.affiliation: Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, SK S7W 5B4, Canada.
authors.forename: Maud C O
authors.initials: MC
authors.lastname: Ferrari
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000502:physiology*; D057231:Climate Change; D057894:Coral Reefs; D004784:Environmental Monitoring; D010473:Perciformes; D011235:Predatory Behavior; D018570:Risk Assessment; D062211:Spatio-Temporal Analysis; D013312:Stress, Physiological; D014466:Ultraviolet Rays
keywords: Alarm cues; Global change; Ocean acidification; Risk assessment; Trait-mediated indirect effects; Ultraviolet radiation