Disentangling tropicalization and deborealization in marine ecosystems under climate change

Type Article
Acceptance Date 2021 IN PRESS
Language English
Author(s) McLean Matthew1, Mouillot David2, Maureaud Aurore3, 4, Hattab Tarek5, Macneil Aaron1, 6, Goberville Eric7, Lindegren Martin4, Engelhard Georg8, 9, Pinsky Malin10, Auber ArnaudORCID11
Affiliation(s) 1 : Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
2 : MARBEC, Univ Montpellier, CNRS, IFREMER, IRD, 34095 Montpellier Cedex, France
3 : Center for Biodiversity and Global Change, Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT 06520, USA
4 : Centre for Ocean Life, c/o National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet Bygning 202, 2800 Kgs. Lyngby, Denmark
5 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Avenue Jean Monnet, 34200 Sète, France
6 : Ocean Frontier Institute, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
7 : Unité Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d’Histoire Naturelle, Sorbonne Université, Université de Caen Normandie, Université des Antilles, CNRS, IRD, 75231 Paris Cedex 05, France
8 : Centre for Environment, Fisheries & Aquaculture Science (Cefas), Pakeðeld Road, Lowestoft NR33 0HT, UK
9 : Collaborative Centre for Sustainable Use of the Seas (CCSUS), University of East Anglia, Norwich NR4 7TJ, UK
10 : Department of Ecology, Evolution, and Natural Resources, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
11 : IFREMER, Laboratoire Ressources Halieutiques, 150 quai Gambetta, BP699, 62321 Boulogne-sur-Mer, France
Source Current Biology (1879-0445) (Elsevier) In Press
DOI 10.1016/j.cub.2021.08.034
Keyword(s) community temperature index, fisheries, marine ecology, thermal affinity, bottom trawl
Abstract

As climate change accelerates, species are shifting poleward and subtropical and tropical species are colonizing temperate environments. A popular approach for characterizing such responses is the community temperature index (CTI), which tracks the mean thermal affinity of a community. Studies in marine, freshwater, and terrestrial ecosystems have documented increasing CTI under global warming. However, most studies have only linked increasing CTI to increases in warm-affinity species. Here, using long-term monitoring of marine fishes across the Northern Hemisphere, we decomposed CTI changes into four underlying processes—tropicalization (increasing warm-affinity), deborealization (decreasing cold-affinity), borealization (increasing cold-affinity), and detropicalization (decreasing warm-affinity)—for which we examined spatial variability and drivers. CTI closely tracked changes in sea surface temperature, increasing in 72% of locations. However, 31% of these increases were primarily due to decreases in cold-affinity species, i.e., deborealization. Thus, increases in warm-affinity species were prevalent, but not ubiquitous. Tropicalization was stronger in areas that were initially warmer, experienced greater warming, or were deeper, while deborealization was stronger in areas that were closer to human population centers or that had higher community thermal diversity. When CTI (and temperature) increased, species that decreased were more likely to be living closer to their upper thermal limits or to be commercially fished. Additionally, warm-affinity species that increased had smaller body sizes than those that decreased. Our results show that CTI changes arise from a variety of underlying community responses that are linked to environmental conditions, human impacts, community structure, and species characteristics.

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McLean Matthew, Mouillot David, Maureaud Aurore, Hattab Tarek, Macneil Aaron, Goberville Eric, Lindegren Martin, Engelhard Georg, Pinsky Malin, Auber Arnaud Disentangling tropicalization and deborealization in marine ecosystems under climate change. Current Biology IN PRESS. Publisher's official version : https://doi.org/10.1016/j.cub.2021.08.034 , Open Access version : https://archimer.ifremer.fr/doc/00720/83243/