Managing Recovery Resilience in Coral Reefs Against Climate-Induced Bleaching and Hurricanes: A 15 Year Case Study From Bonaire, Dutch Caribbean

Abstract

Coral reefs are among the world's most endangered ecosystems. Coral mortality can result from ocean warming or other climate-related events such as coral bleaching and intense hurricanes. While resilient coral reefs can recover from these impacts as has been documented in coral reefs throughout the tropical Indo-Pacific, no similar reef-wide recovery has ever been reported for the Caribbean. Climate change-related coral mortality is unavoidable, but local management actions can improve conditions for regrowth and for the establishment of juvenile corals thereby enhancing the recovery resilience of these ecosystems. Previous research has determined that coral reefs with sufficient herbivory limit macroalgae and improve conditions for coral recruitment and regrowth. Management that reduces algal abundance increases the recovery potential for both juvenile and adult corals on reefs. Every other year on the island of Bonaire, Dutch Caribbean, we quantified patterns of distribution and abundance of reef fish, coral, algae, and juvenile corals along replicate fixed transects at 10 m depth at multiple sites from 2003 to 2017. Beginning with our first exploratory study in 2002 until 2007 coral was abundant (45% cover) and macroalgae were rare (6% cover). Consecutive disturbances, beginning with Hurricane Omar in October 2008 and a coral bleaching event in October 2010, resulted in a 22% decline in coral cover and a sharp threefold increase in macroalgal cover to 18%. Juvenile coral densities declined to about half of their previous abundance. Herbivorous parrotfishes had been declining in abundance but stabilized around 2010, the year fish traps were phased out and fishing for parrotfish was banned. The average parrotfish biomass from 2010 to 2017 was more than twice that reported for coral reefs of the Eastern Caribbean. During this same period,

Commentary: Managing Recovery Resilience in Coral Reefs Against Climate-Induced Bleaching and Hurricanes: A 15 Year Case Study From Bonaire, Dutch Caribbean

“…In a recent Caribbean wide review by Jackson et al (2014) all available coral cover data till 2012 were compiled and for Bonaire results for each research group are also shown in Figure 1 (Figure 6.2 page 185 in the Jackson et al, 2014 report). It is evident from this figure that cover estimates of Steneck and coworkers are quite high compared to the other research groups and again in Steneck et al (2019) they are so high that the authors claim that Bonaire with an average coral cover of ∼47% is actually doing better than the Caribbean maximum measured in the period [1970][1971][1972][1973][1974][1975][1976][1977][1978][1979][1980][1981][1982][1983]. Throughout the manuscript this significant claim is at no point compared to other recent assessments of the Bonaire reef status, even though these coral cover estimates are significantly higher than data for Bonaire collected by us since the 70's (Bak and Nieuwland, 1995;Bak et al, 2005;De Bakker et al, 2016 and other researchers (e.g., Sommer et al, 2011).…”

“…A closer look at the methods of Steneck et al (2019) reveals two issues of concern in making comparisons between the authors' estimate of coral cover and other published estimates. First, their method of estimating coral cover differs from conventional methods.…”

“…In Steneck et al (2019) Bonaire is presented as being an example of a high resilient reef with a remarkable high coral cover ( Figure 10, page 8; reproduced here in Figure 1). In a recent Caribbean wide review by Jackson et al (2014) all available coral cover data till 2012 were compiled and for Bonaire results for each research group are also shown in Figure 1 (Figure 6.2 page 185 in the Jackson et al, 2014 report).…”

Coral reef restoration efforts in Latin American countries and territories

“…The lack of natural recovery of Caribbean coral reefs [11] has spurred the need for active management programs to assist in their recovery [12,13]. Management actions include effective spatial planning, enforcement, no take zones, treatment of sewage and protection of adjoining ecosystems such as mangroves [12,[14][15][16]. Resilience-based management of coral reefs [17] may stimulate coral recovery, especially if applied in conjunction with active restoration [13,18].…”

Interventions to help coral reefs under global change—A complex decision challenge

“…Another avenue is to build ecosystem resilience by further improving conventional management interventions and their governance [6]. Reducing nutrient pollution [24,25], limiting herbivore overfishing [26] and removing coral predators [27] can support resilience by enhancing coral growth and survival. This is so because (i) sediments have direct negative effects on coral recruitment and growth [28,29], and (ii) nutrient run-off in combination with herbivore overfishing reduce coral resilience by favouring the growth and survival of algae which prevent coral recruitment [30,31].…”