Effective climate change refugia for coral reefs

Refining reef‐coral refugia

“…We share the appreciation of the need to search for microrefugia from climate change at <1 km 2 (Mosblech et al ., ), particularly on coral reefs, as suggested by Keppel & Kavousi (). Although such an analysis is desirable, Keppel & Kavousi () correctly state that ‘relevant environmental data to facilitate downscaling oceanic environment models to sufficiently fine scales (≤1 km 2 ) is currently not available for marine environments'. We would encourage analyses using such high‐resolution data, if they were available, but it is unreasonable to urge analysis of data that does not yet exist.…”

“…The two environmental variables were used as our main predictors because: (i) corals extract most of their metabolic resources from their endosymbionts that photosynthesize, and (ii) symbiotic dysfunction, observed as coral bleaching and subsequent coral mortality, occurs through the interaction between high light (photoinhibition) and high‐temperature anomalies. Keppel & Kavousi () suggested that we examined only ‘one global stressor (ocean warming)’ when in fact we examined two stressors – temperature and irradiance – and the interaction between these variables. They also suggested that we ignored ‘ocean acidification’, which we did purposefully.…”

“…Keppel & Kavousi () argued that we only examined generalist coral species. We selected twelve coral species based on their long‐term response to a major thermal stress in Okinawa, Japan (Loya et al ., ; van Woesik et al ., ), including: (i) four coral species that were long‐term ‘winners’, (ii) four coral species that did not appear to change in abundance over the 10‐year Okinawan study, and (iii) four coral species that were long‐term ‘losers’ (van Woesik et al ., ).…”

Beyond the “Deep Reef Refuge” Hypothesis: A Conceptual Framework to Characterize Persistence at Depth

“…Overall, it should be noted that with multiple long-term stressors in play, such as continued increases in ocean temperature, the magnitude of storms, and acidification (Keppel and Kavousi 2015;Kavousi and Keppel 2018), an overall depth refugium role for MCEs would probably be unlikely.…”

“…Consequently, there has been increasing interest in identifying areas that can offer a temporary or long-term escape from such disturbances (Glynn 1996;Riegl and Piller 2003;Karnauskas and Cohen 2012;van Hooidonk et al 2013;Cacciapagla and van Woesik 2015;Smith et al 2017b), or alternatively, that can persist due to higher resilience (Guest et al in revision). Such areas can range from geographic regions (e.g., cooler temperatures associatedswith higher latitude) and localities (e.g., with favorable oceanographic conditions or wind-exposure protection), to distinct habitats within a reef system (Glynn 1996;Keppel and Kavousi 2015). Identification of such areas is crucial in marine protected area planning, to safeguard coral reefs from other stressors and promote the potential of such areas to act as a source of propagules to recolonize affected areas (Ridgway and Hoegh-Guldberg 2002;McCook et al 2009;Guest et al in revision).…”