Simplification, not “tropicalization”, of temperate marine ecosystems under ocean warming and acidification

Ocean warming is altering the biogeographical distribution of marine organisms. In tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At divide between temperate and tropical communities, causing macroalgal forest loss spread corals, fishes other species, termed “tropicalization”. A lack field research into combined effects ocean acidification means there a gap in our ability to understand plan for changes coastal ecosystems. Here, we focus on tropicalization trajectory ecosystems becoming coral-dominated systems. We conducted surveys situ transplants at natural analogues present future conditions under (i) (ii) both transition zone kelp show that increased herbivory by warm-water exacerbates negates any benefits range extending corals growth physiology latitudes. Our data that, as ratchet up, lose forests but do not gain scleractinian corals. plus leads overall habitat shift simple turf-dominated ecosystems, rather than complex tropicalized systems often seen alone. Simplification habitats CO2 levels cascades through ecosystem could have severe consequences provision goods services.