Coral Recovery in the Central Mexican Pacific 20 Years after the 1997–1998 El Niño Event

Violeta Martínez-Castillo,Fabián Alejandro Rodríguez-Zaragoza,Amílcar Leví Cupul-Magaña,Alma Paola Rodríguez-Troncoso,Anderson B Mayfield

doi:10.3390/oceans3010005

Abstract

El Niño–Southern Oscillation (ENSO) events are increasing globally in both frequency and strength, and they can elicit coral bleaching events. The 1997–1998 ENSO caused mass coral mortality with a 96% decline in live coral cover along the Central Mexican Pacific. However, in recent years, these sites have shown signs of recovery. We used data collected in 1997 and 2015–2017 to evaluate the coral recovery in this region and coral cover levels have now reached 50% of their pre-1997–1998 El Niño values. Furthermore, a strong 2015–2016 ENSO event did not significantly affect the live coral cover, potentially demonstrating that the local corals have acclimatized or even adapted to higher temperatures. Even though branching species remain the most abundant morphotype, a PERMANOVA revealed significant changes in the coral assemblage. Collectively, this dataset is testament to the fact that corals within this region are capable of resisting or at least partially recovering from thermal anomalies caused by ENSO events.

Highlights

Coral reefs, considered to be amongst the most ecologically and economically valuable marine ecosystems [1,2], are declining worldwide due to increasing seawater temperatures brought upon by climate change [3,4,5]; half of the coral reefs of the world have been already lost [6]
When abnormally high temperatures persist for extended periods, coral bleaching can occur
The in situ coral cover was determined by scuba diving from eight survey times at depths of ~3 m before the 1997–1998 El Niño–Southern Oscillation (ENSO) event and in 2015, 2016, and 2017

Summary

Introduction

Coral reefs, considered to be amongst the most ecologically and economically valuable marine ecosystems [1,2], are declining worldwide due to increasing seawater temperatures brought upon by climate change [3,4,5]; half of the coral reefs of the world have been already lost [6]. Given the reef coral dependency on their photosynthetically active endosymbionts for food, bleaching can result in a partial or complete coral colony mortality followed by the degradation of the reef [7]. El Niño–Southern Oscillation (ENSO) events, which can feature temperatures of + 2–3 ◦ C above the summer maxima for extended periods (usually six weeks or more), can cause bleaching events, mass coral mortality (and, reductions in the coral cover), and reef degradation [9]. Since the 1980s, four strong ENSO events have caused a massive global loss of coral, and three of them (1982–1983, 1997–1998, and 2015–2016) have been harmful to coral ecosystems in the Eastern Tropical Pacific (ETP) [4,10,11,12]

Methods

Results

Conclusion