Ephemeral effects of El Niño–Southern Oscillation events on an eastern tropical Pacific coral community

Abstract

Coral-reef ecosystems of the central Mexican Pacific have been routinely affected by both moderate and severe El Niño–Southern Oscillation (ENSO) events over the past 20 years. Such conditions are associated with abnormally high (1997–1998, 2002–2003, 2009–2010, and 2015–2016; ‘El Niño’) and low (1999–2000, 2008–2009, and 2010–2011; ‘La Niña’) seawater temperatures. Because few studies have documented how ENSO events affect both corals and key coral competitors such as macroalgae, we evaluated the short- and long-term changes in the cover of three reef coral genera, namely, Pocillopora, Pavona and Porites, as well as four coral competitors, namely, macroalgae, turf algae, coralline algae (CCA) and sponges, over a multi-year period that encapsulated two strong ENSO events: the 2010–2011 La Niña and the 2015–2016 El Niño. Such temperature anomalies caused a short-lived decrease in coral cover, alongside a concomitant increase in CCA. The communities eventually returned to their coral-dominated states within several months of the ENSO events, suggesting that these reef habitats can recover from such episodes of anomalous seawater temperatures.