Biodiversity and reefs at risk

Some threatened reefs stand out as part icularly important from a biodiversity perspective. As part of the Reefs at Risk analysis, we worked with collaborators at the University of York in England, and Ocean Voice International in Canada to integrate data on reef fish species diversity with our data on potential threats to coral reefs. This allows for analysis of the likely degree of threat in areas of high reef fish richness – those having species counts in the top 20 percent of values found around the world. As noted below, our results are rudimentary, given the incompleteness of the fish species dataset. At least 11 percent of the world’s reefs qualify as “biodiversity hot spots”: areas of high species richness that are also under high threat. As the map “Most areas with high reef fish species diversity are threatened …” shows in red, most of these sites are located in Southeast Asia (almost a quarter of this region’s reefs classify), especially in waters off the Philippines, Indonesia, and Japan. As a proportion of total reef area, the Caribbean emerges as another large hot spot: about 18 percent of Caribbean reefs exhibit high coral reef fish species counts, and are at high risk. This includes most of the coral communities of Jamaica, Puerto Rico, and the Lesser Antilles (Guadeloupe, Dominica, Martinique, and other islands). It should be noted that the analysis of areas of high reef fish biodiversity is biased in favor of coral reef areas that are more intensively surveyed. For example, the analysis suggests that there are no hot spots in the Middle East, but, in fact, levels of biodiversity in parts of the Red Sea reach similar levels to the hot spots in the Caribbean. Because a greater proportion of species present in the Caribbean were sampled relative to other areas, these areas achieve relatively high species counts, warranting inclusion in this analysis. Several other areas likely to have comparable diversity that were not included are the reefs off the coast of Vietnam and the Spratly Islands. Additional hot spot areas were identified off the Comoros, Tanzania, and Fiji.

Most areas with high reef fish species diversity are threatened … Data sources: Data on coral reef fish species diversity come from the University of York (U.K.) and Ocean Voice International (Canada). The classification of potential threat to coral reefs was developed as part of the Reefs at Risk analysis at the World Resources Institute, using a data set reflecting the location of shallow coral reefs of the world from the World Conservation Monitoring Centre (U.K.). Note: This map shows areas of known high reef fish species diversity (areas in excess of 210 species), classified by estimateed threat to reefs in that area.

What does this imply, in terms of priorities for immediate protection? Some scientists advocate taking a “portfolio approach” to selecting new sites for protection as parks and reserves. they say that planners and managers should protect important biodiversity sites that are threatened and sites where human pressure and human disturbance are low – where it is easier to create and maintain parks and reserves.

About 17 percent of the world’s reefs exhibit high coral reef fish species richness, and are presently classified at low risk from human activities. More than half of these low-risk, high-diversity sites (shown in dark blue on the map, above) are located in the central and western Pacific, especially within waters off Australia and Papua New Guinea. Large tracts of qualifying reefs occur off the Maldives, Chagos Archipelago, Cuba, the Bahamas, Belize, and southern Mexico.

It should be noted that there are many ways to define important biodiversity areas beyond simply looking at total species count (species richness).

These include endemism (the proportion of species found nowhere else), the number and percentage of rare species found, and protection of unique types of coral reef communities (ecosystem representation), among others.

An ideal assessment would examine conservation importance at both the species level (examining endemics and total species) and the ecosystem level (examining unique habitats). This analysis considers only total species count for one taxonomic group – coral fish species – and not the total count of all species. In choosing priorities for protection, many planners also consider nonbiological criteria, such as identifying sites to protect on the basis of economic and social values.

One major consideration in identifying conservation priorities is the degree to which sites are already protected as parks and reserves. Unfortunately, the data and maps used for this analysis were too coarse to allow detailed examination of protected area gaps (existing marine protected area data are also incomplete and/or are not adequately spatially referenced).

The map – “…and most areas with high reef fish species diversity are not protected” – provides an idea of some of the possible gaps in protection in Southeast Asia. Many areas in the Philippines and Indonesia have high species diversity, are highly threatened, and are not protected.

… and most areas with high reef fish species diversity are not protected

Data sources: Data on coral reef fish species diversity come from the University of York (U.K.) and Ocean Voice International (Canada). The classification of potential threat to coral reefs was developed as part of the Reefs at Risk analysis at the World Resources Institute, using a data set reflecting the location of shallow coral reefs of the world from WCMC. Marine Protected Area locations also come from WCMC.