Temperature patterns and mechanisms influencing coral bleaching during the 2016 El Niño

Authors

Tim R. McClanahan, Wildlife Conservation Society
Emily S. Darling, Wildlife Conservation Society
Joseph M. Maina, Wildlife Conservation Society
Nyawira A. Muthiga, Wildlife Conservation Society
Stéphanie D’agata, Wildlife Conservation Society
Stacy D. Jupiter, Wildlife Conservation Society
Rohan Arthur, Nature Conservation Foundation, Mysore
Shaun K. Wilson, Marine Science Program
Sangeeta Mangubhai, Wildlife Conservation Society
Yashika Nand, Wildlife Conservation Society
Ali M. Ussi, The State University of Zanzibar
Austin T. Humphries, University of Rhode Island
Vardhan J. Patankar, Centre for Wildlife Studies
Mireille M.M. Guillaume, Museum National d'Histoire Naturelle
Sally A. Keith, Lancaster Environment Centre
George Shedrawi, Marine Science Program
Pagu Julius, Mafia Island Marine Park
Gabriel Grimsditch, International Union for the Conservation of Nature
January Ndagala, Tanga Coelacanth Marine Park
Julien Leblond, Wildlife Conservation Society

Document Type

Letter to the Editor

Date of Original Version

11-1-2019

Abstract

Under extreme heat stress, corals expel their symbiotic algae and colour (that is, ‘bleaching’), which often leads to widespread mortality. Predicting the large-scale environmental conditions that reinforce or mitigate coral bleaching remains unresolved and limits strategic conservation actions1,2. Here we assessed coral bleaching at 226 sites and 26 environmental variables that represent different mechanisms of stress responses from East Africa to Fiji through a coordinated effort to evaluate the coral response to the 2014–2016 El Niño/Southern Oscillation thermal anomaly. We applied common time-series methods to study the temporal patterning of acute thermal stress and evaluated the effectiveness of conventional and new sea surface temperature metrics and mechanisms in predicting bleaching severity. The best models indicated the importance of peak hot temperatures, the duration of cool temperatures and temperature bimodality, which explained ~50% of the variance, compared to the common degree-heating week temperature index that explained only 9%. Our findings suggest that the threshold concept as a mechanism to explain bleaching alone was not as powerful as the multidimensional interactions of stresses, which include the duration and temporal patterning of hot and cold temperature extremes relative to average local conditions.

Publication Title, e.g., Journal

Nature Climate Change

Volume

9

Issue

11

Citation/Publisher Attribution

McClanahan, Tim R., Emily S. Darling, Joseph M. Maina, Nyawira A. Muthiga, Stéphanie D’agata, Stacy D. Jupiter, Rohan Arthur, Shaun K. Wilson, Sangeeta Mangubhai, Yashika Nand, Ali M. Ussi, Austin T. Humphries, Vardhan J. Patankar, Mireille M. Guillaume, Sally A. Keith, George Shedrawi, Pagu Julius, Gabriel Grimsditch, January Ndagala, and Julien Leblond. "Temperature patterns and mechanisms influencing coral bleaching during the 2016 El Niño." Nature Climate Change 9, 11 (2019). doi: 10.1038/s41558-019-0576-8.