Coral reef ecosystems are facing many threats including overexploitation of fish stocks, climate change, and habitat degradation. Over the past decade, scientists and government agencies have formulated a more holistic approach to marine resource assessment that evaluates the major threats to ecosystem structure and function in a coordinated fashion rather than treating impacts such as overfishing, habitat degradation, and socioeconomic benefits independently.
NOAA's Ecosystem Approach to Management recognizes that ecosystem health is influenced by many interacting components including species sustainability, biodiversity of the system, quality of the habitat, and benefits to society. Assessing ecosystem health holistically necessitates a framework to allow for evaluation of all of these components simultaneously. The integrated Reef Ecosystem Evaluation Framework (iREEF) methodology was derived from the Integrated Fisheries Risk Assessment Method for Ecosystems (IFRAME) developed by Zhang and colleagues, and this methodology is being adapted and applied to coral reef ecosystems in Florida and Hawaii (Zhang et al. 2009, 2011). iREEF is a collaborative project between NOAA's Pacific Island Fisheries Science Center, the University of Miami, and Pukyong National University, Korea. The methodology utilizes management science tools for breaking down complex decision analysis problems into a set of component parts. iREEF evaluates the status of a marine ecosystem relative to four objectives nested within each species and fishery: sustainability (S), biodiversity (B), habitat quality (H), and socioeconomic conditions (E) (Figure 1). Within each objective, a suite of indicator variables are examined relative to target and limit reference points for each species within each fishery (Table 1).
Figure 1.- The hierarchical iREEF framework compiling objectives: sustainability (S), biodiversity (B), habitat (H), and socioeconomic conditions (E) for the Objectives Risk Index (ORI), the Species Risk Index (SRI), the Fisheries Risk Index (FRI), and the Ecosystem Risk Index (ERI).
Table 1.- Sample of objectives, attributes, and indicators to be used in iREEF assessment.
|Sustainability||Size at first capture||Minimum size limit (Lc)|
|Biodiversity||Incidental catch||Incidental rate (BC/C)|
|Diversity||Species Richness Index|
|Habitat||Coral cover||Percent coral coverage|
|Habitat protection||Prohibited area from fishing|
|Local sustainability||(Domestic production) / (Imports)|
Key indicators are selected, converted to risk scores, and compiled in the iREEF assessment. For each indicator, status is evaluated relative to target and limit reference points. Risk scores are assigned based on a scale that ranges from 0 (low risk below an ecosystem threshold) to 2 (high risk above an ecosystem threshold). The conversion to a risk score depends upon the key indicator being analyzed. Once all of the key indicators are converted to risk scores, the iREEF assessment can proceed.
The iREEF framework is especially advantageous because it allows for synthesis of disparate sources of information. It is a tool that produces a risk score for the entire ecosystem, considering key objectives of sustainability, biodiversity, habitat quality, and socioeconomics. Upon completion of this assessment, iREEF allows pinpointing of high risk sources so appropriate management actions can be taken to reduce the risk to the ecosystem. The product of iREEF is a score card for the ecosystem, allowing for easy comparison across multiple dissimilar ecosystems.