FN Archimer Export Format PT J TI High Coral Recruitment Despite Coralline Algal Loss Under Extreme Environmental Conditions BT AF Tanvet, Clement Benzoni, Francesca Peignon, Christophe Thouzeau, Gerard Rodolfo-Metalpa, Riccardo AS 1:1,2;2:3;3:1;4:2;5:1; FF 1:;2:;3:;4:;5:; C1 ENTROPIE – UMR 9220 (CNRS, IRD, UR, UNC, IFREMER), Institut de Recherche pour le Développement, Nouméa, New Caledonia LEMAR – UMR 6539 (CNRS, IRD, UBO, IFREMER), Institut Universitaire Européen de la Mer, Plouzané, France Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia C2 IRD, FRANCE CNRS, FRANCE UNIV KING ABDULLAH KAUST, SAUDI ARABIA UM LEMAR ENTROPIE IN WOS Cotutelle UMR DOAJ copubli-france copubli-int-hors-europe IF 3.7 TC 4 UR https://archimer.ifremer.fr/doc/00777/88903/94506.pdf https://archimer.ifremer.fr/doc/00777/88903/94507.docx LA English DT Article DE ;coral recruitment;crustose coralline algae (CCA);extreme environmental conditions;persistence;natural variability AB The crucial role of crustose coralline algae (CCA) in inducing hard coral larval settlement and ensuring the replenishment of coral reefs is widely accepted, and so are the negative effects of anthropogenic CO2 emissions on both CCA abundance and coral development. However, diversified and well-developed coral reef communities have been recently discovered in natural conditions where CCA and corals would not be expected to thrive. Back-reef pools, volcanic CO2 vents, mangrove estuaries, and semi-enclosed lagoons systems can present seawater pH, temperature, and dissolved oxygen values reaching or even exceeding the conditions currently predicted by the Inter Panel on Climate Change (IPCC) for 2100. In the semi-enclosed lagoon of Bouraké (New Caledonia, southwest Pacific Ocean), seawater pHT, dissolved oxygen, and temperatures regularly fluctuate with the tide reaching respectively minimum values of 7.23 pHT units, 2.28 mg O2 L-1, and maximum of 33.85°C. This study reports the effect of such extreme environmental conditions on hard coral recruitment and CCA originally settled at a forereef on artificial substrates that were transplanted over two years in two fringing reef and at the Bouraké lagoon. Our data emphasize the negative effects of the extreme conditions in our study sites on the CCA, which decreased in cover by ca. 80% and lost in the competition with turf algae, which, in turn, increased up to 162% at the end of the two years. Conversely, hard coral recruitment remained high at Bouraké throughout the study, three-fold higher than at two sites located outside Bouraké where environmental conditions were typical for coastal fringing reefs. Our findings show that while such extreme, climate change like-conditions have a direct and adverse effect on CCA abundance, and despite a certain persistence, coral larvae settlement was not affected. Based on previous findings from Bouraké, and the present observations, both coral recruits and adults seem to be unaffected despite the extreme environmental conditions. This study supports previous research illustrating how extreme natural and variable environments may reveal unexpected and positive insights on the processes underlying coral acclimatization and adaptation to global change. PY 2022 PD JUL SO Frontiers In Marine Science SN 2296-7745 PU Frontiers Media SA VL 9 UT 000823231300001 DI 10.3389/fmars.2022.837877 ID 88903 ER EF