Reefs at Risk: A Map-Based Indicator of Threats to the Worlds Coral Reefs

This report presents the first-ever detailed, map-based assessment of potential threats to coral reef ecosystems around the world. "Reefs at Risk" draws on 14 data sets (including maps of land cover, ports, settle-ments, and shipping lanes), information on 800 sites known to be degraded by people, and scientific expertise to model areas where reef degradation is predicted to occur, given existing human pressures on these areas. Results are an indicator of potential threat (risk), not a measure of actual condition. In some places, particularly where good management is practiced, reefs may be at risk but remain relatively healthy. In others, this indicator underestimates the degree to which reefs are threatened and degraded.Our results indicate that:Fifty-eight percent of the world's reefs are poten-tially threatened by human activity -- ranging from coastal development and destructive fishing practices to overexploitation of resources, marine pollution, and runoff from inland deforestation and farming.Coral reefs of Asia (Southeastern); the most species-rich on earth, are the most threatened of any region. More than 80 percent are at risk (undermedium and high potential threat), and over half are at high risk, primarily from coastal development and fishing-related pressures.Overexploitation and coastal development pose the greatest potential threat of the four risk categories considered in this study. Each, individually, affects a third of all reefs.The Pacific, which houses more reef area than any other region, is also the least threatened. About 60 percent of reefs here are at low risk.Outside of the Pacific, 70 percent of all reefs are at risk.At least 11 percent of the world's coral reefs contain high levels of reef fish biodiversity and are under high threat from human activities. These "hot spot" areas include almost all Philippine reefs, and coral communities off the coasts of Asia, the Comoros, and the Lesser Antilles in the Caribbean.Almost half a billion people -- 8 percent of the total global population -- live within 100 kilometers of a coral reef.Globally, more than 400 marine parks, sanctuaries, and reserves (marine protected areas) contain coral reefs. Most of these sites are very small -- more than 150 are under one square kilometer in size. At least 40 countries lack any marine protected areas for conserving their coral reef systems

Marine protected area planning in a changing climate’ in Coral reefs and climate change: science and management

Abstract The establishment of Marine Protected Areas (MPAs) has become an important part of society's approach to conserving coral reefs. Protected area managers now must attempt to take account of climate change in the design and implementation of MPAs. A network of MPAs provides a logical way to distribute their benefits to the wider reef system of which they are part, and to minimize the risk that spatially unpredictable and unmanageable insults of any type may decimate all protected areas. This chapter reviews the types of environmental factors and settings that might be considered in the network design process. We focus mainly on environmental factors that appear to confer ecological resilience to bleaching, and also briefly touch on physiological resistance conferred to corals by some strains of zooxanthellae. Finally, our chapter provides a model outlining these four actions that MPA managers may take to build resilience into coral reef conservation programs: 1) spread risk by protecting multiple examples of a full range of reef types; 2) identify and protect coral communities that demonstrate bleaching resistance and may thus increased contribute genetically based bleaching resistance to recovering areas; 3) incorporate connectivity into MPA and network design; and 4) increase effectiveness and flexibility of reef management strategies

Precursors for resilience in coral communities in a warming climate: a belief network approach

This paper explores how successful management interventions might benefit coral reefs during the period of climate warming that is expected in coming decades. To aid this task we have developed a prototype decision-support tool, called ‘ReefState’, which integrates the outcomes of management interventions within a ‘belief network’ of connected variables that describe future warming, coral damage and coral recovery. In a case study applied to the inshore waters of the central Great Barrier Reef, Australia, our worst case scenarios, like several others, suggest that reefs will become devoid of significant coral cover and associated biodiversity by 2050. Even under more optimistic (low) rates of future warming, the persistence of hard coral dominated reefscapes beyond 2050 will be heavily reliant on 2 things, the ability of corals to increase their upper thermal bleaching limits by ~0.1°C per decade, and management that produces local conditions that constrain excessive algal biomass proliferation during inter-disturbance intervals. Despite being perturbed by a global warming process, management of local ecological factors will thus be of critical importance in shaping the future trajectories of coral reef ecosystems

Predictions of phototroph communities in the Hydrographers Passage region, central Great Barrier Reef.

<p>GEO only and GEO-ENV both predicted suitable habitat along the outer-self, although model results were more accurate in areas with multibeam (right hand side) compared to singlebeam echosoundings (left). GEO also predicted higher habitat suitability on the deeper flanks of emergent reefs inside the GBR lagoon.</p

Habitat suitability models for phototrophs for a section of central Great Barrier Reef.

<p>(a) GEO; (b) GEO-ENV; (c) ENV; and (d) BEST.</p

Estimated habitat area for phototroph and heterotroph communities using both Lowest Presence (LPT) and 10^th Percentile thresholds in square km (km²).

<p>GEO indicates the total area estimated.</p

Examples of phototrophic and heterotrophic mesophotic communities on the Great Barrier Reef.

<p>Phototrophic communities shown in (a), (b), and heterotrophy communities in (c), (d). Photo (a) by Ed Robert at Mantis Reef, (b), (c) and (d) taken by <i>Sirius</i> autonomous underwater vehicle (Australian Centre for Field Robotics) at Hydrographers Passage.</p