The Mesoamerican Reef

At over 1000 km in length, the Mesoamerican Reef (MAR) is a near-continuous reef system within four different countries: Mexico, Guatemala, Belize, and Honduras. MAR is the largest reef system in the Northern Hemisphere and is comprised of fringing and barrier reefs and offshore atolls, which extend into deeper water where mesophotic coral ecosystems (MCEs; 30-150 m depth) are found. Scientific studies of MCEs in the MAR began in the 1970s, and despite a rapid increase in marine research throughout the region in recent years, MCE ecological research has been restricted to a few locations and has been focused on hard (scleractinian) corals and fish communities. Hard corals have been documented at a maximum depth of 102 m in the MAR. However, hard corals do not represent the dominant benthic community at mesophotic depths in most cases. The benthic organisms providing structural habitat on many of the known MAR MCEs are octocorals, sponges, black corals, and calcareous macroalgae. Studies on MAR fish communities showed that a large proportion of fish species are found on both shallow reefs and MCEs. The limited data available suggests that MCEs are likely widespread along the MAR. There is evidence of the negative effects of fisheries, sedimentation, harvesting of black corals, and invasive lionfish on MAR MCEs. Improved identification and increase of biological and ecological studies of MCEs, coupled with an extension of scope to include mesophotic habitats in managed areas, should be undertaken to enhance their protection in the region.