AUTHOR=Pereira Pedro H. C. , Lima Gislaine V. , Pontes Antônio V. F. , Côrtes Luis G. F. , Gomes Erandy , Sampaio Cláudio L. S. , Pinto Taciana Kramer , Miranda Ricardo J. , Cardoso Andrei Tiego Cunha , Araujo Julia Caon , Seoane José Carlos Sícoli 

TITLE=Unprecedented Coral Mortality on Southwestern Atlantic Coral Reefs Following Major Thermal Stress

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.725778

DOI=10.3389/fmars.2022.725778

ISSN=2296-7745

ABSTRACT=<p>Thermal stress is now considered the major recent cause of coral reef degradation; yet few studies have been conducted describing those effects on Southwestern Atlantic (SWA) reefs. The SWA represents a coral endemism hotspot with low-functional redundancy and therefore high extinction risk. Recent research has suggested a “thermal refuge” potential for SWA; however, evidence could suggest a different trend. We report herein an unprecedented coral mortality on the largest coastal Brazilian Marine Protected Area (MPA) following the worst thermal stress event since 1985. Degree Heating Week (DHW) values over 4.0 were observed for 107 days, averaging 8.70 for the period, with a maximum of 12.1. Average live coral cover was reduced by 18.1% while average turf algae cover increase by 19.3%. Mortality was highest for three coral species, with a mean mortality of 50.8% per transect for <italic>Millepora braziliensis</italic>, 32.6% for <italic>Mussismilia harttii</italic> and 16.6% for <italic>Millepora alcicornis</italic>. Our unique data for SWA indicates that the populations of two Brazilian endemic species (<italic>Millepora braziliensis</italic> and <italic>Mussismilia harttii</italic>) are under severe threat from global warming and that overall coral cover has been dramatically reduced. Hence, the idea of a possible “thermal” refugia within the SWA must be taken with caution for this coral endemism hotspot.</p>