Shared by Mexico, Belize, Honduras, and Guatemala, the Mesoamerican Reef (MAR), stretches over 1,000 km, and is the largest continuous reef in the Western Hemisphere. Alteration of the natural landscape for development, road construction, or agriculture can have adverse impacts on coral reefs through increased delivery of sediment, nutrients, and other pollutants to coastal waters. Threats from land clearing are higher in areas of steep slope, intense precipitation, and erosive soils.

Appropriate land-use practices in erosion-prone areas are essential for the management of watersheds to ensure that the transport of sediment, nutrients, and other pollutants to coral reefs is minimized. In the Mesoamerican region, over 300,000 hectares of land is allocated to the production of banana, oil palm, sugar cane, citrus, and pineapple crops. Eroded sediments as well as the residues of fertilizer and pesticides used in these industries drain through the rivers and streams and enter coastal waters along the Mesoamerican reef.

As part of the International Coral Reef Action Network (ICRAN) Mesoamerican Reef (MAR) project, WRI partnered with UNEP-World Conservation Monitoring Centre (WCMC) and the World Wildlife Fund (WWF) to provide comprehensive watershed analysis to complement the ICRAN MAR project’s activities on Sustainable Fisheries and Sustainable Tourism.

The ICRAN MAR watershed analysis was developed to produce information and tools for examining the potential impact of different land use and development options in the region and the associated impacts on water quality on the MAR. The project aims to:

• Link patterns of land use within watersheds to the impacts at coral reefs, and identify reefs at greatest risk of degradation;
• Identify watersheds most vulnerable to erosion and those which contribute the most sediment and pollution to coastal waters;
• Adapt tools to forecast potential trends, evaluate different policy or development options, and facilitate improved land management within the region;
• Use the results of the models and diagnostic tools to help educate and encourage key stakeholders to adopt a suite of “better management practices” to reduce impacts on the coastal and marine resources.

The watershed project includes analytical components looking at land cover change and the associated impacts on runoff, erosion, and sediment and pollutant delivery to and transport within coastal waters. It also includes on-the-ground activities with agricultural businesses to implement better management practices.

Many local partners were consulted on modeling methods, for data input and evaluation, and on agricultural management practices. The partners’ roles:

• UNEP-WCMC – developed scenarios of land cover change and provided land cover data sets as input to the hydrologic modeling;
• WRI – implemented the watershed delineation and hydrologic analysis for the MAR region, performed analysis of vulnerability to erosion, and coordinated the circulation modeling along the MAR;
• WWF – led the work with agri-business (banana, pineapple, citrus and sugar) to implement better management practices, focused on reducing the presence of pesticides in the MAR marine environment and controlling soil erosion from major commercial agricultural sectors.

The ICRAN Mesoamerican Reef project was supported by the U.S. Agency for International Development (USAID) and the United Nations Foundation (UNF). The project is executed in conjunction with the United Nations Environment Programme – Caribbean Environment Programme (UNEP-CEP).