Resources Overview
Coral reefs and communities occur throughout Mexico but are concentrated in four main areas: the Gulf of California and Pacific Coast; the nearshore reefs between Tampico and Veracruz in the western Bahía de Campeche; the more distant offshore reefs of the Campeche Bank; and the fringing reef and atolls of the Caribbean Sea.

Hermatypic corals were originally considered to be rare in the Mexican Pacific, but recent research has described abundant coral populations in these reefs, despite their small size (mostly a few hectares or less) and their discontinuous occurrence. True reefs with an elevated structure occur at Cabo Pulmo, Ensenada Grande on Isla Espíritu Santo, Punto Chileno, Islas Marías and at scattered locations along the southern coast of Oaxaca. Coral communities, sometimes with abundant coral growth but little net accretion, are present in the central Gulf of California from Isla Angel de la Guardia to Bahía Concepción. They consist of just two species – Porites panamensis and P. sverdrupi – which are tolerant of the low temperatures of the upper gulf. The latter is an endemic species believed to be a relict from the Pliocene undergoing a natural process of extinction. Other communities occur all along the Pacific coast, occupying rocky areas at 0-15 meters in depth. The communities at Isla Jaltemba, Huatulco Bays, east of Puerto Angel, Puerto Angelito and Carrizalillo are particularly well developed but are composed of only a few species, mainly Pocillopora spp., Porites spp., Pavona spp., Psammocora spp. and Fungia spp. The latest El Niño and post-El Niño events in 1997 and 1998 caused considerable bleaching and mortality around Bahía Banderas and Huatulco, but had considerably less impact at some other localities.

Some 200 kilometers south of Baja California and 600 kilometers west of mainland Mexico, lies a small but important group of four volcanic islands, the Islas Revillagigedo. They lie in deep oceanic water and are broadly impacted by a westward flowing North Equatorial Current, which is fed by the cold California Current and the warmer Costa Rica Coastal Current. These relatively harsh conditions are exacerbated by regular tropical storms. Despite this, the islands harbor the most diverse fish and coral communities in the Mexican Pacific. Reef development is limited, but there are some true reef structures, notably in the more sheltered bays. Twenty hermatypic coral species have been recorded around these islands, dominated by Pocillopora spp., as well as Porites lobata and P. lichen. Many gorgonian species have also been recorded. Biogeographically the islands appear to be more closely linked with Clipperton Atoll than the Mexican mainland and up to three of the hermatypic coral species found on the islands may be endemic to these two areas. Additionally, six molluscs and 12 reef fish have been found to be endemic to the islands.

In the Gulf of Mexico reefs occur in the south, and are mostly located along the edge of the continental shelf, both around Veracruz and on the Campeche Bank, which follows the western and northern edges of the Yucatan Peninsula. The majority of the Veracruz reefs are platform reefs, some with emergent parts, as in Isla Lobos, although patch reefs do exist in El Giote off Anton Lizardo and at Punta Gorda, Punta Majagua, Hornos and Punta Mocambo. Sedimentation is very high on reefs close to the port of Veracruz where the rivers Antigua, Papaloapan and Alvarado limit coral growth, and diversity in these areas is low. The Campeche reefs have ecological and morphological characteristics that distinguish them from the Caribbean reefs of Mexico, although their fauna is similar. Both emergent (eg Cayos Arcas, Cayos Arenas and Arrecife Triángulos) and submerged (eg Banco Nuevo, Banco Ingles, Bajo Serpiente, Madagascar and Sisal) reefs are present. All are platforms rising from a pre-Holocene base located at a depth of 50-60 meters. Arrecife Alacranes is an atoll.

The most extensive reef development in the country is in the state of Quintana Roo on the east coast of the Yucatan Peninsula. Here the continental shelf is very narrow, in many places less than 2 kilometers wide. There are partly submerged fringing reefs along much of this coastline, while from Xcalak southwards there is a fully developed fringing reef which continues to Ambergris Key in Belize, and then extends into the Belize Barrier Reef. Extensive spur and groove systems have developed in the center and south. This coastline is noted for its lack of rivers but numerous limestone sink holes result in an outflow of freshwater at various points. Offshore are two further important features: Cozumel Island, a relatively large island in the north with a number of reefs on both windward and leeward shores; and close to the Belize border the large atoll of Banco Chinchorro, which is separated from the mainland by a 1 000 meter deep channel. The reefs are well developed on the eastern (windward) side of this atoll: coral cover is lower in the shallow waters, and a spur and groove system has developed. The lagoon is generally sandy, with extensive seagrass cover and some patch reefs. Both Banco Chinchorro and Cozumel modify the northerly flow of water in the Caribbean Current. South of Cozumel, part of the current is funnelled into the channel and accelerates up to 4 knots to form the Yucatan Current. Its speed is believed to influence sedimentation rates and possibly coral larvae settlement, particularly in the Playa del Carmen area. Considerable declines in coral cover at Puerto Morelos and nearby reefs have been related to the impacts of Hurricane Gilbert in 1988 and a large but unquantified bleaching event in 1995. However, unlike in Belize to the south, the combined impacts of the bleaching and Hurricane Mitch – the Atlantic’s fourth strongest hurricane on record – did not lead to widespread coral mortality along this coastline.