title: Tropical herbivores provide resilience to a climate-mediated phase shift on temperate reefs.
abstract: Climate-mediated changes to biotic interactions have the potential to fundamentally alter global ecosystems. However, the capacity for novel interactions to drive or maintain transitions in ecosystem states remains unresolved. We examined temperate reefs that recently underwent complete seaweed canopy loss and tested whether a concurrent increase in tropical herbivores could be maintaining the current canopy-free state. Turf-grazing herbivorous fishes increased in biomass and diversity, and displayed feeding rates comparable to global coral reefs. Canopy-browsing herbivores displayed high (~ 10,000 g 100 m(-2) ) and stable biomass between 2006 and 2013. Tropical browsers had the highest abundance in 2013 and displayed feeding rates approximately three times higher than previously observed on coral reefs. These observations suggest that tropical herbivores are maintaining previously kelp-dominated temperate reefs in an alternate canopy-free state by grazing turfs and preventing kelp reestablishment. This remarkable ecosystem highlights the sensitivity of biotic interactions and ecosystem stability to warming and extreme disturbance events.
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Bennett
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wernberg
authors.affiliation: Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia.
authors.forename: Euan S
authors.initials: ES
authors.lastname: Harvey
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Julia
authors.identifier: http://orcid.org/0000-0001-7961-3552
authors.initials: J
authors.lastname: Santana-Garcon
authors.affiliation: Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Saunders
mesh_terms: D000818:Animals; D001315:Australia; D057231:Climate Change; D057894:Coral Reefs; D005399:Fishes; D060434:Herbivory; D044423:Kelp; D014329:Tropical Climate
keywords: Climate change; coral reef; fishes; kelp; regime shift; tropicalisation