Coral reef resilience

STINAPA report

Mass coral bleaching is becoming more frequent and widespread and poses a major threat to coral reefs worldwide. Mass coral bleaching is a response to thermal stress triggered by high Sea Surface Temperatures (SSTs) or ultraviolet radiation attributed to changing regional and global climate patterns. Since 2016, STINAPA Bonaire has surveyed the severity of coral bleaching in the Bonaire National Marine Park at 10 sites on the leeward coast. Each year, corals exhibited signs of thermal stress including paling, partial bleaching, and fully bleaching, but no mortality. Since 2016, the year with the lowest percentage of corals affected was 2018 (9%) and the year with the highest percent of corals affected was 2020 (61%). Corals deeper in the water column were more susceptible to thermal stress in all years, but susceptibility trends by site were not consistent throughout the study. While addressing the global-scale causes of coral bleaching is daunting, STINAPA Bonaire monitors the severity of coral bleaching and helps develop local management strategies that may improve the resistance and resilience of coral reefs in the Bonaire National Marine Park to climate change.

The International Union for the Conservation of Nature (IUCN) assumed leadership of the Global Coral Reef Monitoring Network (GCRMN) in 2010 with three primary objectives:

1. Strengthen scientific understanding of the status and trends of coral reef ecosystems at different places around the world.
2. Improve communication among the scattered members of the Network.
3. Make reef data publicly available online in a timely fashion.

The purpose of our new scientific endeavor is to establish quantitatively rigorous baselines for earlier reef conditions and to document the extent to which different reefs have varyingly declined from a relatively more pristine to degraded state. This variability is the key to understanding why some reefs have much more abundant corals than others; knowledge that is essential for preserving and restoring coral reefs and their ecosystem services in the foreseeable future.

Because of the enormity of the task, we plan to focus on separate biogeographic regions in a stepwise fashion, and then combine all of the results for a global synthesis by 2016. We have begun in tropical America because this is the region with which we are most familiar and to refine our methods of analysis before moving on to other regions. This report describes the results of our very preliminary Caribbean analysis. It will be followed closely by an assessment of the tropical eastern Pacific. This work will be completed in 2012.

The three major components of the scientific effort are to:

1. Document quantitatively the status and trends for all routinely monitored components of coral reef ecosystems, including reef corals, macroalgae, other sessile benthos, sea urchins, and fishes based on data provided by individual researchers as well as the scientific literature, monitoring programs, and reports;
2. Conduct workshops to bring together people who collected the data to directly involve them in data analysis and synthesis; 
3. Interpret variations in status and trends in relation to independent environmental, management, and socioeconomic data to better understand what are the primary natural and anthropogenic factors driving coral reef decline and how they may be more effectively alleviated,

We assembled 36 scientists from 18 countries and territories to assess status and trends of Caribbean reefs at our first workshop held at the Smithsonian Tropical Research Institute (STRI) in the Republic of Panama 29 April to 5 May, 2012. Discussions were based upon initial exploratory analyses of approximately half the 253 data sets obtained so far from 29 countries. Trajectories of status and trends were constructed for reefs from seven countries with additional data for reef fish.

Three general points are clearly evident from these preliminary analyses:

1. The routine analytical procedure of ecological change on reefs that combines data from distant sites obscures important ecological differences among geographic locations and habitats of crucial importance for policy and management.
2. Some Caribbean reef ecosystems are relatively intact compared to average conditions in the region. For example, many reefs in the Netherlands Antilles and Cayman Islands have 30 % or more live coral cover, little macroalgae, and a moderate (albeit strongly depleted) abundance of fish. In contrast, reefs in Jamaica and the US Virgin Islands have well below 10% live coral cover, abundant macroalgae, and virtually no fish larger than a few cm.
3. The causes of these regional differences in reef conditions are not well understood beyond the obvious role of human exploitation and disturbance. Caribbean reefs with the highest surviving coral cover and least macroalgae tend to be characterized by little land-based pollution, some degree of fisheries regulations and enforcement, moderate economic prosperity, and lower frequency of hurricanes, coral bleaching, and disease. Unraveling the potential interactive role of these and other factors is a major goal of our study once all the necessary data are available.

More extensive and detailed results will be presented in a draft Caribbean Synthesis Report in December 2012, to be published and made available online by March 2013. We also plan to follow up with a second Caribbean workshop immediately preceding the 2013 ICRI Meeting in Belize to bring together members of the different GCRMN Caribbean nodes to explore ways the results of the scientific analysis can be used to improve the effectiveness of Caribbean reef monitoring and policy. 

Abstract:

Although Bonaire’s coral reefs remain among the healthiest and most resilient in the Caribbean, this IUCN report based on the IUCN Resilience Assessment of Coral Reefs highlights some of the threats that exist to Bonaire’s coral reefs, and which could have serious implications for resilience to future climate change and other threats. The report identified recommendations for addressing the current threats, as well as high and low resilience sites.

The threats and recommendations identified include:

Coastal development and artificial beaches.
Recommendation: All coastal construction on Bonaire should be strictly regulated and follow the construction guidelines. The guidelines should become law in order to be enforced appropriately.

Leaching from septic tanks.
Recommendation: It is strongly recommended that Bonaire invest in appropriate sewage treatment facilities to improve water quality and increase the resilience of its valuable coral reefs. It is also recommended that a water quality monitoring program be set up and sustained.

Increasing damselfish populations.
Recommendation: It is recommended that the fishing of predatory fish species on Bonaire’s coral reefs be controlled and managed to a sustainable level to prevent population explosions of prey fish capable of modifying the reef habitat.

Trididemnum and Lobophora.
Recommendation: It is recommended that the populations of Trididemnum and Lobophora are closely monitored and the factors contributing to the unnatural abun- dance of these coral-overgrowing organisms should be studied and then eliminated.

Due to a variety of factors affecting resilience which were assessed using the IUCN methodology, sites were also ranked according to their overall resilience: 

It is noteworthy that sites with lowest resilience ratings (e.g. Chachácha) are those most impacted by coastal development, while sites with highest resilience ratings (e.g. Marine Reserve North, Playa Frans, Karpata, Margate Bay, Vista Blue and South Bay) are those furthest away and least impacted by coastal development.