Tropicalisation of temperate marine ecosystems
Ocean warming is causing many species to shift their distribution towards the poles and major ecosystem changes can occur when formerly separated species come into contact. Voracious tropical herbivores are moving into temperate regions and interacting for the first time with temperate seaweed forests.
While tropical reefs require intense herbivory to maintain coral dominance, overgrazing on temperate reefs causes phase shifts, from productive underwater forests to defoliated barrens. Intruding tropical herbivores have already caused phase shifts and a ‘tropicalisation’ of ecological communities in Japan and the Mediterranean; we present novel evidence that this may be a phenomenon of global importance.