Clarifying the concept of climate change refugia for coral reefs

Abstract

Refugia can facilitate the persistence of biodiversity under changing environmental conditions, such as anthropogenic climate change, and therefore constitute the best chance of survival for many coral species in the wild. Despite an increasing amount of literature, the concept of coral reef refugia remains poorly defined; so that climate change refugia have been confused with other phenomena, including temporal refuges, pristine habitats and physiological processes such as adaptation and acclimatization. We propose six criteria that determine the capacity of refugia to facilitate species persistence, including long-term buffering, protection from multiple climatic stressors, accessibility, microclimatic heterogeneity, size, and low exposure to non-climate disturbances. Any effective, high-capacity coral reef refugium should be characterized by long-term buffering of environmental conditions (for several decades) and multi-stressor buffering (provision of suitable environmental conditions with respect to climatic change, particularly ocean warming and acidification). Although not always essential, the remaining criteria are important for quantifying the capacity of potential refugia.

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

“…Our projection also suggested a northward shift of suitable habitat for many commercially important deep-sea fishes, a finding consistent with the hypothesis of a poleward expansion in response to climate change (Jones et al, 2013;Perry et al, 2005;Poloczanska et al, 2013). Our study projected very limited, discrete climate-change refugia for cold-water corals, and especially octocorals, highlighting the need for accurate fine-scale climate grids and methodologies to properly identify climate refugia (Ashcroft, 2010;Kavousi & Keppel, 2018;Valdimarsson, Astthorsson, & Palsson, 2012).…”

“…Our projection also suggested a northward shift of suitable habitat for many commercially important deep‐sea fishes, a finding consistent with the hypothesis of a poleward expansion in response to climate change (Jones et al, ; Perry et al, ; Poloczanska et al, ). Our study projected very limited, discrete climate‐change refugia for cold‐water corals, and especially octocorals, highlighting the need for accurate fine‐scale climate grids and methodologies to properly identify climate refugia (Ashcroft, ; Kavousi & Keppel, ; Keppel et al, ; Valdimarsson, Astthorsson, & Palsson, ). Occupancy of the future suitable habitats will depend on connectivity pathways and will differ greatly between deep‐sea fishes which have juvenile and adult mobility and the cold‐water corals which can only disperse as larvae (Andrello, Mouillot, Somot, Thuiller, & Manel, ; Baco et al, ; Hilário et al, ).…”

The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

“…What we do know is that our understanding of conditions optimal for refugia is increasing, but that the heterogeneous nature of reef systems challenges the ability for environments to act as refuge against multiple abiotic parameters. Effective refugia have recently been described by Kavousi and Keppel (2017) as needing to provide long-term buffering to multiple-stressors. As such, consideration could be given to environmental engineering to facilitate the suite of conditions required for effective refugia, e.g., artificial shading (Coelho et al, 2017).…”

Biological interactions: The overlooked aspects of marine climate change refugia

“…Since marine refugia are not strongly decoupled from their surroundings (Kavousi & Keppel, 2018), biological threats in refugia and refuges can sometimes appear with catastrophic impacts (see e.g., Bongaerts, Ridgway, Sampayo, & Hoegh-Guldberg, 2010). Notably, there does not appear to be a practical barrier to maintaining refugial capacities-the ability of refugia to mitigate the magnitude, duration, and increased rate of stressors-under the indirect impacts of climate change.…”

“…Without effective management plans, even the least vulnerable ecosystems may be at risk (see Beyer et al, 2018). Such strategies can also reduce non-climate change stressors, which should not be ignored while identifying marine refugia (Kavousi & Keppel, 2018). I emphasize my understanding of how the suggested study structure can be complicated, time-consuming, and costly to perform.…”