Impact of El Niño 2015-2016 on the coral reefs of the Pacific of Costa Rica: the potential role of marine protection

Abstract

Introduction: El Niño 2015-2016 was considered one of the most severe worldwide, causing the third global event of coral bleaching. Previous high-intensity El Niño events (1982-83 and 1997-98) caused high coral mortalities and deterioration of coral reef structures along the Eastern Tropical Pacific, affecting both ecosystem and associated economical activities. Objective: The aim of this study was to determine the impact of the most recent El Niño event on coral reefs from Cocos Island and the Pacific coast of southern Costa Rica. Methods: Coral reefs were surveyed before (2013-2014) and after (2016) the disturbance, using underwater visual censuses within belt transects, to quantify the bottom coverage at different depths. Results: In general, average live coral cover decreased 50% after the 2015-2016 El Niño event, with Golfo Dulce being the most affected area with 75% of live coral cover decline. However, in certain localities such as Isla del Coco and Isla del Caño, the effects of El Niño were apparently minimal, since no substantial loss of live coral cover was detected. Differences in the level of deterioration found between coral reefs could be related to several factors, including the age of the protected area, the distance to centers of human population, and the effectiveness in the application of management strategies. Conclusions: The synergistic impact of the 2015-16 El Niño event and other stressors (e.g. illegal fishing and unregulated coastal human development) increased the levels of disturbance on coral reefs, threatening their structure and functioning. It is necessary to strengthen conservation strategies in order to improve the resilience of coral reefs to the impact of natural and anthropogenic disturbances. Concrete actions such as coral reef restoration, marine environmental education, and marine spatial planning must become important tools to maintain the good health of coral reefs and ensure the sustainability of the goods and services provided by these ecosystems.

Coral reef resilience to thermal stress in the Eastern Tropical Pacific

“…one or more surveys at the same coordinates on the same reef; Jackson et al., 2014). There were no data available for 1973, from the Guayaquil region, nor sufficient published coral cover data to analyse the most recent El Niño event 2015–2016, although data on this event are now starting to be published (Alvarado et al., 2020; Cruz‐García, Rodríguez‐Troncoso, Rodríguez‐Zaragoza, Mayfield, & Cupul‐Magaña, 2020). Figure S1 describes the number of surveys by region and year.…”

Micro-Fragmentation as an Effective and Applied Tool to Restore Remote Reefs in the Eastern Tropical Pacific

“…The Eastern Tropical Pacific (ETP) coral reef communities are declining, experiencing anthropogenic and climate change impacts, including several major coral bleaching and mortality events, resulting from the El Niño–Southern Oscillation (ENSO) phenomena. Live coral cover has been reduced from 33% to 7% with >90% local coral mortalities caused by these extreme thermal anomalies in the last 30 years [ 16 , 37 , 38 , 39 , 40 , 41 , 42 ]. Yet, some ETP reefs reveal fast recovery [ 9 , 12 , 16 , 41 , 43 , 44 , 45 , 46 ], and life history patterns of certain branching and massive coral reef species have shown high thermal tolerance thresholds [ 14 , 16 , 47 , 48 , 49 , 50 ].…”

Diversidad de los hábitats submareales de la Península de Santa Elena e Islas Murciélago, Pacífico Norte, Costa Rica

“…En estudios realizados por Alvarado et al (2011Alvarado et al ( , 2015Alvarado et al ( , 2016Alvarado et al ( , 2018Alvarado et al ( , 2020 en arrecifes del Pacífico, se ha observado que, por lo general, las algas tienden a tener un tamaño menor a 10 cm de alto y suelen formar tapetes. Sin embargo, en la zona norte de Costa Rica es común encontrar macroalgas de más de 10 cm de altura.…”

“…En el Pacífico costarricense, los ambientes marinos más estudiados han sido principalmente los arrecifes rocosos, los arrecifes y comunidades coralinas, las zonas rocosas intermareales, las playas y los manglares (Cortés, 2016). En Costa Rica, los estudios de diversidad se han concentrado en los ambientes más someros, desde las zonas intermareales hasta los 10 m de profundidad, posiblemente relacionado con las facilidades en el muestreo y con especies de importancia comercial, y por lo tanto son sitios que han tenido mejores medidas de conservación en el país (Alvarado, Beita-Jimenez, Mena, Fernández-García, Cortés, Sánchez-Noguera, Jimenez & Guzmán-Mora, 2018;Alvarado, Beita, Mena, Fernández-García, & Guzman-Mora, 2015;Alvarado, Beita, Mena, Fernández-García, Guzman-Mora & Cortés, 2016;Alvarado, Herrera, Corrales, Asch, & Paaby, 2011;Alvarado, Sánchez-Noguera, Arias-Godínez, Araya, Fernández-García & Guzmán, 2020;Samper-Villareal, Bourg, Sibaja-Cordero, & Cortés, 2014;Sibaja-Cordero & Cortés, 2009;Sibaja-Cordero & Vargas-Zamora, 2006). También se han realizado investigaciones en ambientes que van de los 10 a los 40 m utilizando buceo autónomo, no obstante, están más relacionados con estudios taxonómicos en grupos como los octocorales (Breedy & Guzmán, 2003).…”