Coral reefs

Abstract:

The Atlantic and Gulf Rapid Reef Assessment (AGRRA) sampling strategy is designed to collect both descriptive and quantitative information for a large number of reef vitality indicators over large spatial scales. AGRRA assessments conducted between 1998 and 2000 across a spectrum of western Atlantic reefs with different histories of disturbance, environmental conditions, and fishing pressure were examined to reveal means and variances for 15 indicators. Twenty surveys were compiled into a database containing a total of 302 benthic sites (249 deep, 53 shallow), 2,337 benthic transects, 14,000 quadrats, 22,553 stony corals. Seventeen surveys contained comparable fish data for a total of 247 fish sites (206 deep, 41 shallow), 2,488 fish transects, and 71,102 fishes. Shallow (≤ 5 m) reefs were dominated by A. palmata, a good proportion of which was standing dead, while deep (>5m) reefs were nearly always dominated by the Montastraea annularis species complex. Fish communities were dominated by acanthurids and scarids with seranids making up less than 1% of the fish seen on shallow reefs and 4% on deep reefs.

AGRRA benthic and fish indicators on deep reefs showed the highest variation at the smallest spatial scale (~<0.1 km), with recent mortality and macroalgal canopy height displaying the largest area and subregional scale (~1-100 km) variation. A mean live coral cover of 26% for the 20 survey areas was determined for the deep sites. Significant bleaching and disease-induced mortality of stony corals associated with the 1998 (El Niño-Southern Oscillation) ENSO event were most apparent in the western Caribbean and Bahamas subregions and the Montastraea annularis complex was the most heavily impacted.

The overall low number of sightings for larger-bodied groupers and snappers (~< 1/100 m2) as a whole suggest that the entire region is overfished for many of these more heavily targeted species. More remote reefs showed as much evidence of reef degradation as reefs more proximal to human coastal development. Characterizing present-day reef condition across the region is a complex problem since there are likely multiple sources of stress operating over several spatial and temporal scales. Not withstanding the many limitations of this analysis, the value of making multiple observations across multiple spatial scales that can approximate the “normal” state for the region today is still very high. 

Abstract:

My thesis research builds on the ‘movement’ to value nature. This movement as I call it started as early as 1970 with a theory to quantify and monetize nature (Hueting, 1970). References to the concept of ecosystem services date back to the mid 1960s and early 1970s (de Groot et al., 2002). A Phd research into the value of nature by De Groot (1992) emphasized the need to “ecologize” economic valuation of ecosystem services by integrating ecological information.

In 2005 the Millenium Ecosystem Assessment (MEA) report used the ecosystem services approach to highlight the importance and drivers of changes of ecosystem service delivery (MEA, 2005). The Economics of Ecosystem services and Biodiversity (TEEB) platform built on the framework of MEA, but specified ecosystems in underlying functions, processes and structures to “ecologize” economic benefits of biodiversity and costs of biodiversity losses (TEEB, 2010a).

Valuation of ecosystem services can be done at three levels, monetary, quantitative and qualitative. Qualitative describes benefits in a non-numerical scale, quantitative measures benefits and changes based on numerical data and monetary builds on quantitative value and attaches a monetary value (White et al., 2011). This research is a semi-quantitative analysis of the functional value of coral reef habitats on Bonaire to support ecosystem services. It is part of an economic valuation study of marine and terrestrial ecosystem services on Bonaire. The economic valuation study estimated a monetary value of selected ecosystem services. My research measured the functional value, defined as the ecological importance of a habitat, on an ordinal scale with four levels (0-3).

The TEEB theoretical framework was applied by studying the underlying ecological functions, processes and structures of coral reefs that determine the capacity to deliver coral reef ecosystem services through a literature review. The functional group approach was used as a measure of the importance of habitats based on the level of representation of fish and coral functional groups. The methodology to analyze the functional value was inspired by a study of Harborne (2006) that established the functional value of Caribbean coral reef, seagrass and mangrove habitats to ecosystem processes.

My research applied this method using Bonaire as case study and adapted the method to determine the functional value of habitats to ecosystem services instead of ecosystem processes. This way the study of Harborne has been taken a step further by making the link between the economic analysis focussing on ecosystem services and the ecological analysis focussing on ecosystem functioning. The other adaptations made were the spatial scale, the habitat types and the data collection method. Harborne determined the value by doing a meta-analysis of empirical literature on processes in ten coral reef, seagrass and mangrove habitat types.

For my research primary data of fish and benthic functional groups were collected at over hundred locations along the entire leeward coast of Bonaire to value just two coral reef habitat types.

Outcome of this research are matrices presenting relationships between socio-economic services and ecological functions, processes and fish and benthic species representing a functional role. Another outcome are maps presenting the functional value of each location to support twelve ecosystem services based on the primary data collected. These maps were analyzed taking into account resource use on Bonaire and show which area are of high importance for each service.

This research is innovative in its attempt to link the economic value of ecosystem services with an ecological value of habitats to support these ecosystem services. In addition the survey of benthic cover and fish biodiversity and abundance has not been done at such a large scale according to our knowledge since the mapping of Bonaire in 1985 (Van Duyl, 1985).