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

Authors

Sylvain Agostini, University of Tsukuba
Ben P. Harvey, University of Tsukuba
Marco Milazzo, Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa)
Shigeki Wada, University of Tsukuba
Koetsu Kon, University of Tsukuba
Nicolas Floc’h, Ecole Européenne Supérieure d’Art de Bretagne
Kosei Komatsu, The University of Tokyo
Mayumi Kuroyama, The University of Tokyo
Jason Hall‐Spencer, School of Biological and Marine Sciences

ORCID

• Jason Hall‐Spencer: 0000-0002-6915-2518

Abstract

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

DOI

10.1111/gcb.15749

Publication Date

2021-07-16

Publication Title

Global Change Biology

ISSN

1354-1013

Embargo Period

2021-08-28

Recommended Citation

Agostini, S., Harvey, B., Milazzo, M., Wada, S., Kon, K., Floc’h, N., Komatsu, K., Kuroyama, M., & Hall‐Spencer, J. (2021) 'Simplification, not “tropicalization”, of temperate marine ecosystems under ocean warming and acidification', Global Change Biology, . Available at: 10.1111/gcb.15749" >https://doi.org/10.1111/gcb.15749