Reefs on the Pacific and Caribbean coasts of Central America are remarkably different. The Pacific coast reefs are small with very low diversity and are under very high pressure from natural impacts and increasing human activities. The reefs have been heavily damaged in the past by crown-of-thorns starfish predation and massive bleaching during El Niño years, and now by large amounts of sediment runoff from poor land-use practices. They are also being continually stressed by cold upwellings and damage from bioeroding animals that burrow into coral skeletons and scrape off newly settled corals. These poor coral growth conditions also result in a low capacity to recover from damage. There has been little activity to conserve them, and pressure is not high for protection, except for a few reefs well offshore.

The eastern coast of Central America has some of the best reefs in the Caribbean. Reefs off Belize, and also those well offshore of countries to the south, have much higher biodiversity and are generally in good to excellent condition; corals are healthy and some reefs have large fish populations. These reefs have been impacted by coral bleaching, including the current episode, and by the death of the long-spined sea-urchin. But they have generally recovered rapidly. They are now being impacted by increased sediment and nutrient runoff from poor land-use practices, and by increasing fishing pressure, often using illegal means. This is particularly clear in reefs off Panama where significant degradation has been measured. There are a number of marine protected areas (MPAs), some well managed but others existing only on paper. Currently there is a major regional project in preparation, under the Mesoamerican Barrier Reef Initiative (MBRI), which aims to increase the capacity for conservation and sustainable use of coral reefs along the northeastern coast of Mesoamerica, and to increase monitoring and assessment of the health of coral reef ecosystems.

The reefs of the two coasts of Central America are radically different: those on the Pacific side are generally small, have very low coral species diversity, having formed along the margins of a steep and narrow continental shelf, and are subject to the influences of upwelling and El Niño. In contrast, reefs on the eastern side have some of the highest coral diversity in the Caribbean, and have formed extensive coral reefs along shallow underwater banks. These include the barrier reef running parallel to the coast of Belize, one of the longest in the world. The Mesoamerican Barrier Reef System covers a distance of nearly 1000 km, originating in the northern Yucatan Peninsula in Quintana Roo (Mexico), and extending as far south as the Bay Islands off the north coast of Honduras. Further south, fringing reefs and the many offshore coral cays from Nicaragua to the San Blas Islands of Panama form a second cluster of reefs with associated mangroves and seagrass beds. Research to date has focused on the ecology and geology of the reefs of Panama and Belize. Only recently have reports of degradation in Mesoamerican reefs begun to focus attention on the need for conservation and management of these systems, and hence a better understanding of their structure and function within a larger regional context.

The Caribbean reefs of Mesoamerica are ecologically complex and subject to a variety of natural and increasing anthropogenic stresses. Coral bleaching was a major event in 1983, causing massive mortality of corals. Hurricanes are a major natural disturbance, periodically destroying vast areas of reefs and clearing the way for new settlement and colonization, particularly in northern parts (as occurred recently with Hurricane Mitch). The long-spined sea-urchin Diadema antillarum played a major role on these reefs, as in the rest of the Caribbean, in controlling the growth of macroalgae. When there was a mass die-off in 1983, algal growth exploded and smothered large areas of coral reefs in most countries, except in Belize where near-normal populations of grazing fish remained. In most other areas, fish populations were reduced through the use of fine mesh fish traps, nets and spearfishing. The most recent bleaching event associated with the 1997–1998 El Niño has had marked effects in the western Caribbean, as elsewhere. The overall mortality from this event is still being assessed, but individual accounts indicate that it is extensive. Recovery rates are likely to be affected by cumulative stress from other anthropogenic sources. These include destructive fishing practices, including inappropriate gear, the use of spear guns, and violation of closed seasons and exploitation of spawning aggregations of reef fish, and indirect sources such as pollution and sedimentation.

Deforestation and inappropriate land use in watersheds draining to the Caribbean have resulted in significant erosion and sediment loads affecting reefs. Non-point source pollution from pesticides and agricultural runoff, as well as wastewater from growing municipal and industrial development along the coast, are degrading coastal water quality and contributing to eutrophication. Coastal tourism and port expansion have resulted in habitat loss and degradation through conversion of mangroves, dredging of seagrass beds, and siltation of reefs. These interactive and cumulative effects are likely to play an increasing role in the dynamics of reef community structure and their resilience to natural disturbance.

Reefs on the Pacific coast are subject to frequent bouts of cold upwelling water, which favour the growth of macroalgae and limit the growth of corals. By contrast, during El Niño years, seawater temperatures can rise to over 30^oC and stay high for weeks, resulting in coral bleaching. Coral diversity is very low because these reefs are isolated from the Pacific centres of high diversity by enormous distances, and from the Caribbean side by land that closed the connection between the two seas 3.5 million years ago. The reefs are usually close to land and are heavily impacted by large amounts of sediment runoff because of heavy rainfall. There is also intense bioerosion by burrowing sea-urchins, boring molluscs, and other animals. This erosion is so intense that most of the reefs are decreasing in coral rock content, not increasing like most other reefs in the world. The crown-of-thorns starfish are persistent predators on these reefs and have caused serious damage in the past.

The combination of stresses on Pacific reefs means that there are very slow rates of recovery following major stress. After the large El Niño bleaching in 1983, it has been estimated that recovery of these reefs may take between 100 and 200 years. Coral reefs that are stressed by either cold upwellings or pollution could take longer to recover.

The longest barrier reef in the Caribbean runs from Belize’s northern border with Mexico, north of Ambergris Caye, down to Honduras, a distance of some 250 km. Virtually all types of reefs are found, from shallow platform reefs in the lagoon to deep plunging barrier reefs on the edge of the shelf. A series of oceanic atolls are found outside the reef; among these are Turneffe, and two of the best examples of oceanic atolls in the Caribbean, Lighthouse and Glover’s Reef. These reefs are probably the best reefs in the Caribbean, as they are in excellent health, have a high diversity of corals, and large fish populations. The major natural impacts are hurricanes, which strike every six years on average, the most severe being Hattie (1961) and Greta (1978), which damaged corals and sent 2 m storm surges over some islands. The recent coral bleaching in late 1998 appears to be particularly severe, with large areas of the reefs showing extensive bleaching of almost all species, and water temperatures rising to 32^oC and as high as 38^oC in protected shallow areas.

Most reefs are relatively remote from the mainland. A lagoon, between 10 km and 40 km wide, separates the barrier reefs from the mainland and protects them from sediment runoff and pollution. In addition, Belize has one of the lowest population densities in the Caribbean and most of the tropical and mangrove forests are intact. Fishing pressure is slight to moderate, however there is increasing pressure from fishers coming up from countries to the south. When the Diadema died off in 1983, there were no major increases in macroalgal growth due to a healthy population of herbivore fish, and so there were few impacts on the corals. The offshore atolls are remote from land influences, however they appear to have reasonably high natural levels of water nutrients and are experiencing increasing fishing pressure.

The excellent status of reefs in Belize is attracting increasing numbers of dive tourists, many of whom explore the reefs aboard small ships. The government is active in promoting coastal conservation and is implementing a phased integrated coastal management program. Belize also signed the Tulum Declaration along with its neighbors: Mexico, Honduras, and Guatemala. These four countries are committed to joint management and conservation of the Mesoamerican Barrier Reef System (MBRS), having acknowledged the need for a coordinated plan of action. A regional project to protect the reefs through better monitoring and conservation techniques is now being prepared with Global Environment Facility and World Bank support, and standards and protocols for sustainable use are being introduced. The Mesoamerican Barrier Reef Initiative (MBRI) is part of a larger program to preserve and expand a biological corridor of natural habitats, connecting populations of flora and fauna along the entire Mesoamerican isthmus, from Mexico to Panama.

Most of the Caribbean coastline consists of sandy beaches with occasional rocky headlands where reef corals grow. There are reefs on offshore carbonate banks in the north, and small areas of fringing and patch reefs down to the Panamanian border. These reefs are exposed to strong onshore winds and waves that limit growth in shallow water. There are also large sediment flows that restrict reef growth, and these sediment flows have increased in the last 20 years. The reefs were extensively damaged by major bleaching in 1983, and algal proliferation from the Diadema die-off, also in 1983. Reefs around the port of Limon have been damaged by sewage, industrial and petroleum pollution. Recent increases in sediment flow have caused considerable damage to coral cover on the large fringing reefs of the Parque Nacional Cahuita (from an average of 40% in the early 1980s to around 11% now). Likewise there has been a major drop in coral cover (now less than 20%) in Refugio Nacional de Vida Silvestre Gandoca-Manzanillo, but here corals are mostly healthy. Other problems for the reefs are coral and sand mining, and dumping of solid wastes. Intensive citrus and banana farming have resulted in pollution from pesticides, fertilizers, and sediment. Both MPAs have had a massive increase in tourist numbers (a three-fold increase between 1981 and 1991).

On the Pacific coast, the fringing reef of Punta Isolotes, Golfo Dulce (near the border of Panama) has been massively degraded by sedimentation, such that coral cover is down to 2%. This was a well-developed reef with a high cover of Porites and Pocillopora corals, but now the reef is virtually extinguished. The best reefs are those of Culebra Bay in the north. These are also under increasing pressure from land runoff and fishing activities, including collection of ornamental fishes and corals. Attempts at protecting these reefs are meeting with resistance from other stakeholders.

Management of Costa Rican reefs has mostly focused on protected area management rather than control of land-based sources of pollution, sedimentation, and other offsite impacts that have devastating effects downstream.

There are a few small reefs at Los Cobanos, which are heavily impacted by land stresses: sediment pollution, and bioerosion. Little is known of these reefs.

The Caribbean coastline is very short and heavily influenced by sediment-laden rivers, thus, there is virtually no coral reef growth near the coast. The Pacific coast is also influenced by alluvial conditions and dominated by mangroves, with negligible coral reef formation.

There are three main reef groups: nearshore fringing reefs; extensive offshore fringing reefs around the Bay Islands (Utila, Roatan, and Guanaja ), Cayos Cochinos and Islas del Cigne in the north central region; and the offshore fringing and patch reefs of the Caya de la Mosquitia (Mosquito Cayes). The Bay Islands have a well-developed structure and high coral diversity, with 44 species known from these islands. A complete inventory of marine biodiversity of the Bay Islands will be undertaken as part of a five-year Natural Resources Management Project for the Bay Islands, supported by the Inter-American Development Bank and the Government of Honduras. A biodiversity monitoring and geographic information system will also be established under the project. This type of monitoring will be critical in assessing the status of coral reefs in this region following the significant bleaching and coral mortality experienced in these otherwise healthy reefs after the El Niño event of summer 1998. This was followed soon after by the devastating Category IV Hurricane Mitch, which struck the coast of Honduras with 155 mph winds in late October. Such natural disturbances, coupled with the prospects for rapidly increasing tourism and migration from the mainland to the Bay Islands, underscores the vulnerability of these reefs and the need for pro-active management. A new marine reserve for the waters around the Bay Islands is under preparation, which will limit fishing and regulate other marine activities. Other plans include control of land-based sources of stress through better land-use planning and environmental management. Elsewhere, for example along the Mosquito Cayes, fishing pressure is more intense and few fish on inshore reefs reach reproductive size. As a consequence, there is significant growth of algae that smothers corals and impedes their growth in areas with high nutrient loads.

As a participant in the Mesoamerican Barrier Reef System Initiative, Honduras will be part of a regional program involving neighboring Belize, Guatemala, and Mexico in monitoring and assessment of coral reef health. Biophysical and socioeconomic information will be processed and disseminated around the region to help build a picture of ecosystem health at the local, national, and regional levels.

There are no reefs on the short Pacific coast of Honduras, which is part of the Gulf of Fonseca, a highly productive zone of upwelling and continental runoff.

There is little information on reefs off both coasts of Nicaragua, but on the east coast there is the largest hard carbonate bank in the Caribbean. On it there are patch and island coral reefs but these are largely unknown. There are four groups: Moskitos Cays; Man-of-War Cays; Cayos de Perlas; and Great and Little Corn Islands. Human occupation of these last islands is resulting in degradation from sewage pollution and over-fishing. There are no reefs off the mainland coast because of the large amounts of sediment runoff. No reefs are reported from the Pacific coast.

Panama is protected from hurricanes and cyclones because it is south of the path of most tropical storms. There is, however, frequent upwelling on the Pacific coast, which limits coral reef growth. Both coasts have experienced coral bleaching in association with El Niño events, the most severe in 1983. The most recent El Niño episode (1998) resulted in only moderate coral bleaching on both the Pacific and Caribbean coasts.

There are three large areas of reefs on the Caribbean side: Bocas del Toro; Region Central from Colon to Portobelo; and the several hundred islands of San Blas. A wide range of reefs occur at Bocas del Toro, ranging from those near the shore and mangroves that are subject to heavy sediment influence, to offshore patch reefs growing down to 15 m in pristine clean water. Exposure to large waves limits coral growth in shallow water to hardy, stunted corals. Behind these are extensive areas of seagrasses, and mangroves with patch reefs, which have low coral cover (less than 20%) because of large sediment flows and high algal overgrowth. Fishing pressure is particularly high, and large fish, lobster, and conch are rare.

The reefs of the Central Region were studied intensively following a major oil spill in 1987. There are mostly shallow fringing reefs in this area in less than 6 m of water, with some extending to depths of 12 m. The oil spill at Bahia Las Minas decreased coral cover and diversity, mainly because the oil was trapped in the mangroves, and continually leached out onto the shallow reefs over many months.

In the 1970s, the San Blas reefs were healthy, with active growth extending down to 30 m and coral cover around 30–55%. There were extensive stands of Porites Porites and elkhorn coral (Acropora palmata) in shallow water, with deeper zones dominated by Agaricia agaricites. Recent studies have shown that more than half of these corals have been lost (now 12–26% cover), either covered in sediment, broken into rubble or, like the Porites, mined for calcium carbonate. These losses are attributed to a combination of many causes including: the die-off of Diadema, which has encouraged algal overgrowth; coral bleaching; increased sediment and nutrient loads from limited agriculture; unplanned coastal development; and coral mining. Algal cover has doubled since the mid-1980s to about 60% on many reefs. The greatest damage has occurred around the 41 inhabited islands near shore with direct disposal of all effluents onto the reefs, and expansion of the islands by infilling the seagrass beds. Fishing pressure, particularly by spearfishing and seine nets, is intense, and local regulations for sustainable management of the resources are ignored. Grouper, lobster, and turtles are exported and their populations are now very low. Coral bleaching in 1983 killed many corals down to 20 m, particularly the dominant coral Agaricia agaricites, whereas the bleaching in 1995 had little impact.

Pacific reefs are mostly small and have low coral diversity with a maximum of 23 coral species, and growth is limited by cold upwellings that promote massive algal blooms and assist large algal growth. Coral growth in the Gulf of Panama occurs almost exclusively as fringing reefs off the islands of Iguana and Pearl. To the north, in the Gulf of Chiriqui, there are reefs both on the mainland and around offshore islands away from oceanic waves. The Coiba Island reef is probably the second largest in the eastern Pacific and covers 160 ha. These reefs were extensively damaged during the 1983 El Niño bleaching event, and have still not recovered.

One coral reef area on the Pacific coast, Coiba, is within a MPA. There has been active cooperation between the local inhabitants of the San Blas Islands, the Kuna Indians, the Smithsonian Tropical Research Institute, and the Panamanian Government to establish the Kuna Biosphere Reserve.

Perceptions of the need for greater reef management have increased with the recognition of the economic value of reefs for tourism and fisheries. This recognition has meant strong development of marine protected areas (MPAs) in Belize and Costa Rica, while Honduras, and to a lesser extent Panama, lag behind. Conservation has been aided by the peace processes between neighbouring countries, and Belize, Guatemala, Honduras, and Mexico are collaborating in a joint initiative for the conservation and sustainable use of the Mesoamerican Barrier Reef System with the assistance of the GEF, the World Bank, and a variety of donors working at the national and regional levels.

These countries have been participating in reef productivity monitoring through CARICOMP (Caribbean Coastal Marine Productivity Program), and research on reefs has been strong in Belize (largely with collaboration from British institutions), and Panama (through collaboration with the Smithsonian Institution of the USA). A more comprehensive ecosystem monitoring and environmental information systems effort will be mounted at the sub-regional level for countries participating in the MBRI.

There are more than 20 MPAs designated along the Caribbean coasts of these six countries, however only a small fraction have effective management plans and staff to assist in conservation. A greater proportion of the reefs of the Western Caribbean will be under protection and active management as part of ongoing national and sub-regional efforts in Mexico, Belize, and Honduras to expand the system of marine protected areas to cover the rich biodiversity and biogeography of the region. Similar efforts will need to be mounted in Nicaragua, Costa Rica, and Panama to ensure that such coverage is truly representative of the region as a whole.

Coral reefs on the Pacific side are poorly developed and generally in poor condition, thus there is little appreciation of these reefs for management. These reefs are heavily stressed by natural and human stresses and recover very slowly from damage. Only two MPAs have been notified: one by Costa Rica on the offshore islands Isla del Coco and another, Coiba Island, off the Gulf of Panama coast.

The region contains a mixture of very good coral reefs, such as those off Belize, but the majority are coming under increasing stress from human activities, combined with the normal natural stresses, resulting in reduced resilience and many degraded reefs. This is particularly the case on the Pacific coast, but these reefs were always marginal and have very low capacity to recover. Current management capacity is generally poor, but there are encouraging signs of greater commitment to conserve the valuable Caribbean reefs in particular.

Jorge Cortés is from the Centro de Investigacion y Ciencias del Mar y Limnologia and the Universidad de Costa Rica in San Pedro, and Marea Hatziolos is senior coastal and marine resources management specialist at the World Bank in Washington, D.C., with projects in Central America.