Climate‐induced changes in the suitable habitat of cold‐water corals and commercially important deep‐sea fishes in the North Atlantic

Abstract

The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep‐sea fauna, thereby compromising key ecosystem services. Understanding how climate change can lead to shifts in deep‐sea species distributions is critically important in developing management measures. We used environmental niche modelling along with the best available species occurrence data and environmental parameters to model habitat suitability for key cold‐water coral and commercially important deep‐sea fish species under present‐day (1951–2000) environmental conditions and to project changes under severe, high emissions future (2081–2100) climate projections (RCP8.5 scenario) for the North Atlantic Ocean. Our models projected a decrease of 28%–100% in suitable habitat for cold‐water corals and a shift in suitable habitat for deep‐sea fishes of 2.0°–9.9° towards higher latitudes. The largest reductions in suitable habitat were projected for the scleractinian coral Lophelia pertusa and the octocoral Paragorgia arborea, with declines of at least 79% and 99% respectively. We projected the expansion of suitable habitat by 2100 only for the fishes Helicolenus dactylopterus and Sebastes mentella (20%–30%), mostly through northern latitudinal range expansion. Our results projected limited climate refugia locations in the North Atlantic by 2100 for scleractinian corals (30%–42% of present‐day suitable habitat), even smaller refugia locations for the octocorals Acanella arbuscula and Acanthogorgia armata (6%–14%), and almost no refugia for P. arborea. Our results emphasize the need to understand how anticipated climate change will affect the distribution of deep‐sea species including commercially important fishes and foundation species, and highlight the importance of identifying and preserving climate refugia for a range of area‐based planning and management tools.

Climate change considerations are fundamental to management of deep‐sea resource extraction

“…We suggest that protection of the marine environment should in- Table S3), ToE of those variables from background natural variability (e.g., Mora et al, 2013; Table S1), local climate velocity (the distance between a current location and its future climate analog; e.g., Brito-Morales et al, 2018, 2020, climate hazard (e.g., FAO, 2019; Table 1; Table S2), and species-specific climate refugia Morato et al, 2020). Ongoing REMP development for the northwest Pacific Ocean and northern MAR offer an excellent opportunity to employ these metrics.…”

Influence of Water Masses on the Biodiversity and Biogeography of Deep-Sea Benthic Ecosystems in the North Atlantic

“…For example, ∆ indicates change between present-day and predicted future conditions. Adapted from Mora et al (2013); Sweetman et al (2017) and Morato et al (2020).…”

“…Based on the projections of Mora et al (2013); Sweetman et al (2017), and Morato et al (2020), which used all available data generated by Earth System Models (Earth System Grid Federation, 2019), we reviewed the forecasted changes in the water mass properties at the seafloor in the deep North Atlantic (20 • -70 • N and 78 • W-10 • E). Namely, we evaluated how potential temperature at the seafloor ( • C), particulate organic carbon (POC) flux at 100 m depth (mg C•m −2…”

“…•d −1 ), DO concentration at the seafloor (ml•l −1 ) and pH at the seafloor, and were forecasted to change from 1951 to 2000 (historical simulation) to 2081-2100 (RCP8.5 or business-asusual scenario). The POC flux at the seafloor was calculated was calculated based on CIMP5 ocean biogeochemical nutrientphytoplankton-zooplankton-detritus models (Fu et al, 2016) and the Martin curve (Martin et al, 1987) with an export depth set to 100 m. Forecasted changes in aragonite and calcite at the seafloor, as described in Morato et al (2020), were also evaluated here. The multimodel averages of the projections of water mass properties based on all available Earth System Models ensure the highest possible precision and accuracy of the predictions (Mora et al, 2013).…”

Rapid deep ocean deoxygenation and acidification threaten life on Northeast Pacific seamounts

“…Models predict that North Atlantic seamounts may act as temporary refugia from deep OA for cold water corals (Tittensor, Baco, Hall-Spencer, Orr, & Rogers, 2010), but that climate-induced changes will ultimately reduce suitable habitat for corals (up to 100% reduction) and fishes, by 2100 (Morato et al, 2020). While Ban, Alidina, Okey, Gregg, and Ban (2016)…”