Editing IPCC:AR6/SROCC/Chapter-5 (section)

===== 5.5.2.1.2 Adaptation in coral reefs =====

Coral reefs are currently threatened by the continuous global degradation of warm water coral reef ecosystems and the failure of traditional conservation actions to revive most of the degrading reefs (Rinkevich, 2008 <sup>[[#fn:r1855|1855]]</sup> ; Miller and Russ, 2014 <sup>[[#fn:r1856|1856]]</sup> ). Interventions to rehabilitate degraded coral reef ecosystems can be categorised as preventive (‘passive’ restoration) or adaptive (‘active’ restoration) (Miller and Russ, 2014 <sup>[[#fn:r1857|1857]]</sup> ; Linden and Rinkevich, 2017 <sup>[[#fn:r1858|1858]]</sup> ) (see Box 5.5).

Inspired by silviculture (forestation) approaches to terrestrial ecosystem restoration, studies (Rinkevich, 1995 <sup>[[#fn:r1859|1859]]</sup> ; Rinkevich, 2005 <sup>[[#fn:r1860|1860]]</sup> ; Rinkevich, 2006 <sup>[[#fn:r1861|1861]]</sup> ; Rinkevich, 2008 <sup>[[#fn:r1862|1862]]</sup> ; Bongiorni et al., 2011 <sup>[[#fn:r1863|1863]]</sup> ) have proposed a two step restoration strategy for warm water coral reefs termed gardening of denuded coral reefs. In the first step, a large pool of coral colonies (derived from coral nubbins and fragments, and from sexually derived spat) are farmed in underwater nurseries, preferably on mid-water floating devices installed in sheltered zones, in which coral material can be cultured for up to several years. In the second step, nursery-grown coral colonies, together with recruited associated biota, are transplanted to degraded reef sites (Shafir and Rinkevich, 2008 <sup>[[#fn:r1864|1864]]</sup> ; Mbije et al., 2010 <sup>[[#fn:r1865|1865]]</sup> ; Shaish et al., 2010b <sup>[[#fn:r1866|1866]]</sup> ; Shaish et al., 2010a <sup>[[#fn:r1867|1867]]</sup> ; Bongiorni et al., 2011 <sup>[[#fn:r1868|1868]]</sup> ; Horoszowski-Fridman et al., 2011 <sup>[[#fn:r1869|1869]]</sup> ; Linden and Rinkevich, 2011 <sup>[[#fn:r1870|1870]]</sup> ; Mbije et al., 2013 <sup>[[#fn:r1871|1871]]</sup> ; Cruz et al., 2014 <sup>[[#fn:r1872|1872]]</sup> ; Chavanich et al., 2015 <sup>[[#fn:r1873|1873]]</sup> ; Horoszowski-Fridman et al., 2015 <sup>[[#fn:r1874|1874]]</sup> ; Lirman and Schopmeyer, 2016 <sup>[[#fn:r1875|1875]]</sup> ; Montoya Maya et al., 2016 <sup>[[#fn:r1876|1876]]</sup> ; Ng et al., 2016; Lohr and Patterson, 2017 <sup>[[#fn:r|]]</sup> ; Rachmilovitz and Rinkevich, 2017 <sup>[[#fn:r1878|1878]]</sup> ). Active restoration of coral reefs, while still in its infancy and facing a variety of challenges (Rinkevich, 2015b <sup>[[#fn:r1879|1879]]</sup> ; Hein et al., 2017 <sup>[[#fn:r1880|1880]]</sup> ), has been suggested to potentially improve the ecological status of degraded coral reefs and the socioeconomic benefits that the reefs provide (Rinkevich, 2014 <sup>[[#fn:r1881|1881]]</sup> ; Rinkevich, 2015b <sup>[[#fn:r1882|1882]]</sup> ; Linden and Rinkevich, 2017 <sup>[[#fn:r1883|1883]]</sup> ).

Ecological engineering approaches may promote coral reef adaptation (Rinkevich, 2014 <sup>[[#fn:r1884|1884]]</sup> ; Forsman et al., 2015 <sup>[[#fn:r1885|1885]]</sup> ; Coelho et al., 2017 <sup>[[#fn:r1886|1886]]</sup> ; Horoszowski-Fridman and Rinkevich, 2017 <sup>[[#fn:r1887|1887]]</sup> ; Linden and Rinkevich, 2017 <sup>[[#fn:r1888|1888]]</sup> ; Rachmilovitz and Rinkevich, 2017 <sup>[[#fn:r1889|1889]]</sup> ). They also include: augmenting functional diversity, including that of the microbiome (Casey et al., 2015 <sup>[[#fn:r1890|1890]]</sup> ; Horoszowski-Fridman and Rinkevich, 2017 <sup>[[#fn:r1891|1891]]</sup> ; Shaver and Silliman, 2017 <sup>[[#fn:r1892|1892]]</sup> ); transplantating whole habitats (Shaish et al., 2010b <sup>[[#fn:r1893|1893]]</sup> ; Gómez et al., 2014 <sup>[[#fn:r1894|1894]]</sup> ); and enhancing genetic diversity (Iwao et al., 2014 <sup>[[#fn:r1895|1895]]</sup> ; Drury et al., 2016 <sup>[[#fn:r1896|1896]]</sup> ; Horoszowski-Fridman and Rinkevich, 2017 <sup>[[#fn:r1897|1897]]</sup> ). Active restoration can contribute to reef rehabilitation in all major reef regions (Rinkevich, 2014 <sup>[[#fn:r1898|1898]]</sup> ; Rinkevich, 2015b <sup>[[#fn:r1899|1899]]</sup> ). However, there is ''limited evidence'' on how resistant these manipulated corals are to global change drivers (Shaish et al., 2010b <sup>[[#fn:r1900|1900]]</sup> ; Shaish et al., 2010a <sup>[[#fn:r1901|1901]]</sup> ) or how the nursery time affects biological traits like reproduction in coral transplants (Horoszowski-Fridman et al., 2011 <sup>[[#fn:r1902|1902]]</sup> ). Coral epigenetics may also be used as an adaptive management tool for reef rehabilitation ( ''low confidence'' ), as suggested by studies on coral adaptation (Brown et al., 2002 <sup>[[#fn:r1903|1903]]</sup> ; Horoszowski-Fridman et al., 2011 <sup>[[#fn:r1904|1904]]</sup> ; Palumbi et al., 2014 <sup>[[#fn:r1905|1905]]</sup> ; Putnam and Gates, 2015 <sup>[[#fn:r1906|1906]]</sup> ; Putnam et al., 2016 <sup>[[#fn:r1907|1907]]</sup> ).

Research on active coral reef restoration (Box 5.5) suggests the potential to help rehabilitate degraded coral reefs, provided that the underlying drivers of the impacts are mitigated ( ''high confidence'' ). Ongoing and new research in active coral reef restoration may further improve active reef restoration outcomes (Box 5.5) ( ''low confidence'' ). However, these coral reef restoration options may be ineffectual if global warming exceeds 1.5 o C relative to pre-industrial levels (Hoegh-Guldberg et al., 2018 <sup>[[#fn:r1908|1908]]</sup> ; IPCC, 2018 <sup>[[#fn:r1909|1909]]</sup> ).

<div id="section-5-5-2-1ecosystem-based-adaptation-block-4" class="box"></div>

<span id="box-5.5-coral-reef-restoration-as-ocean-based-adaptation"></span>