Conserving potential coral reef refuges at high latitudes

Abstract

Aim High-latitude coral reef communities composed of tropical, subtropical and temperate species are heralded as climate change refuges for vulnerable tropical coral reef species, giving them high, but as yet unrealized, conservation priority. We review the ecology of subtropical reefs in the context of climate change and evaluate management strategies ensuring both their own continuity and their potential to act as refuges for tropical species.Location Global high-latitude coral reef environments.Methods We review the literature about refuges management, high-latitude reefs, climate change effects on reef organisms and the conservation of reefs.Results High-latitude coral reef systems are functionally different from their tropical counterparts, characterized by unique biogeographical overlap of taxa at their range margins, endemic species and strong seasonality in species composition. They are shaped by marginal environmental conditions, which are predicted to undergo greater changes than reefs at lower latitudes, resulting in community re-assembly through range shifts, altered dispersal patterns, survivorship and habitat loss. The combined impact of these changes, however, is difficult to assess, as some effects may be antagonistic. Climate change conservation options include passive management strategies such as no-take reserves that aim to minimize local disturbances, and active strategies such as relocating populations to refuge sites. Success of active intervention relies on the long-term persistence of relocated populations, which is unlikely for highlatitude populations once source tropical populations at lower latitudes are locally extinct.Main conclusion High-latitude reefs are poised for rapid modification under climate change. Management should anticipate these changes by setting up no-take reserves on suitable subtropical reefs now to foster ecosystem resilience through reduced anthropogenic impacts. Given the uncertainty over which species will arrive or depart and lack of knowledge about the history of most subtropical reef development, active management is presently not the best use of management resources.

Climate Change and Active Reef Restoration—Ways of Constructing the “Reefs of Tomorrow”

“…This would preserve and enhance the species/genotypic diversity of depleted reef assemblages for any future need, including reef restoration measures, aimed at boosting coral reefs' resilience. It is our view that the use of coral nurseries as active depositories for coral reef assemblages is superior to other suggested notions, for example assisted colonization [55], or to the use of high-latitude coral reef communities as climate change refuges for vulnerable tropical coral reef species [56]. Furthermore, the opportunity to develop nurseries into small refugia for reef assemblages will insure the conservation of species with unknown but potentially key ecological functions, such as the "Sleeping Functional Groups" [57] that may efficiently enhance coral-reef recovery.…”

A Victorian emigrant: first observation and range extension of the nudibranch Tenellia catachroma (Burn, 1963) in Western Australia (Mollusca: Gastropoda)

“…In southern Australia, both the east and west coasts are vulnerable to marine climate change, with southward shifts in distribution a likely outcome (Przeslawski et al 2008;Beger et al 2014;Richards et al 2016). Several recent range extensions have been reported for sea slugs on the east coast and these may be attributed to a combination of increased survey effort and shifts in distribution in response to ocean warming (Nimbs et al 2015;, 2017.…”

Levels of intervention – reducing SCUBA-diver impact within subtropical marine protected areas

“…These reefs are influenced by both tropical and temperate currents, creating highly variable environments (Suthers et al, 2011). Species diversity is high due to endemism and the overlapping of species at range edges (Beger, Sommer, Harrison, Smith, & Pandolfi, 2014).…”

“…Gibson, Van der Marel, and Starzomski (2009) state that subtropical zones could potentially provide environmental 'stepping stones' for a range of species during climate-driven range shifts, making subtropical zones high conservation priorities (Beger et al, 2014;Hoegh-Guldberg & Bruno, 2010).…”

“…Harriott and Banks (2002) found that within Australian subtropical communities, scleractinian corals can be found at, or close to, their southern range limit, whilst Ecklonia radiata kelp inhabits its northern limit. With the East Australian Current bringing tropical water of offshore areas and wind-driven cooler currents close to shore, there is also an inshore-to-offshore gradient with inshore reefs supporting algae-dominated habitat and offshore sites supporting more corals (Beger et al, 2014;Malcolm, Davies, Jordan, & Smith, 2011).…”