Persistence of tropical herbivores in temperate reefs constrains kelp resilience to cryptic habitats

Global warming is facilitating the range expansion of tropical herbivores, causing a tropicalization temperate marine ecosystems, where herbivores can suppress habitat-forming macrophytes, supporting resilience canopy-free ecosystem states. However, currently we lack thorough understanding mechanisms that, on one hand, support persistence and other recovery foundation species in tropicalized required knowledge to predict potential regime shifts reversals baseline state ecosystem. This study tested processes behind reefs which experienced complete loss their kelp forests an influx following heatwave 2011. For this, assessed feedback that maintain turf-dominated states (recruitment browsing grazing rates turf cover) those resist it (kelp recruitment, survival reproductiveness). We found remained with high abundances after 9 years from shift. The rabbitfish Siganus fuscescens chub Kyphosus bigibbus were most important whose was supported by adjacent reef lagoon, seagrass meadows backreef habitats hosted juveniles both species, particularly rabbitfish. Tropical exerted strong top–down control seaweed during herbivory assays, rapidly consuming individuals open areas. topographical refuges reefs, low survived, some having reproductive tissue. Synthesis. Our findings incorporate importance nursery grounds for refugia into model, former increases latter might facilitate recovering populations. restoration abundant warm-resistant populations shelters could provide local sources propagules recolonize spaces; however, our results suggest reduction provision turf-free substratum would be necessary boost forests.