Maranhao mangroves

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Red mangrove (Rhizophora mangle) (Source: http://www.panoramio.com/photo/7441064)

Introduction

The mangroves of the Maranhão ecoregion are the most extensive and most structurally complex in Brazil, and also reach the greatest heights (up to 45 meters) as well as the greatest aboveground forest biomass of mangroves anywhere in the world. This is in part attributable to the diverse characteristics of the shoreline, and to high levels of freshwater input from the extensive rivers and from high amounts of rainfall, and to high tidal ranges.

Location and General Description

This mangrove ecoregion is divisible into eastern and western parts, to either side of the Bahía de São Marcos, where the island of São Luis is located. The eastern part consists of extensive sand dunes interspersed with mangroves, which are restricted to river mouths and bays. The western part, which receives fined grained sediment deposited by the Amazon River, consists of hundreds of islands and mudflats. These are continuously colonized and stabilized by mangroves, which cover the coastal fringe and also penetrate inland along its numerous rivers, bays, and estuaries. Because of flat topography and high tidal ranges, that average 4 meters (m) but are known to exceed 8 m in some locations, saline waters and mangroves can be found over 40 kilometers (km) inland. The climate is hot and humid, with a mean annual temperature of 26°C. Annual precipitation is also high, averaging 2,500 millimeters (mm) but reaching levels of over 4,000 mm. Because of high freshwater inputs from rainfall as well as from numerous rivers, mangrove vegetation is also found associated with palms and freshwater macrophytes. Towards the eastern side of the north coast of Brazil, mangroves are progressively less developed because of higher salinity and longer dry seasons.

Biodiversity Features

The mangroves of the Maranhão ecoregion are one of the most important areas for shorebirds in South America - approximately 200,000 were found in censuses conducted in 1982 and 1986 or 50% of Brazil's total population of shorebirds and 7% of South American shorebirds that have been verified. They are also an important feeding and reproductive area for herons (Ardeidae) and spoonbills (Ajaia ajaja).

Rhizopora mangle is the most frequently occurring mangrove species and is found closest to the coast at heights of up to 25 m. Also particularly well developed along the north coast of Brazil is Avicennia germinans and A. schaueriana, which may be over 1 meter in diameter and reach heights of up to 45 meters. Other true mangrove species found in this region are R. racemosa, R. harrisonii, Laguncularia racemosa and Conocarpus erectus. Non-tree species associated with these mangroves are Spartina alterniflora that grows on the seaward fringe, and Hibiscus tiliaceus and the fern Acrostichum aureum, that are both found in the landward margins and dry saline areas within mangroves. Species found associated with these mangroves because of their location adjacent to tropical forests and because of high freshwater input include the tropical forest species, leguminosae vine (Dalbergia brownei), and Apocynaceae liana (Rhabdadenia biflora); freshwater macrophytes, Araceae Montrichardia arborescens, and Leguminosae Mora oleifera; and palm species, Euterpe oleracea and Orbygnia martiana.

Rare and endangered species include the birds scarlet ibis (Eudocimus ruber), and wattled jacana (Jacana jacana), the mammals tucuxi (Sotalia fluviatilis) and manatee Trichechus manatus, and several marine turtles, for whom it is a breeding area.

Current Status

This ecoregion contains approximately 36% of the total Brazilian mangrove area, which is largely intact because of low population density and poor accessibility. Protected areas include the Bacanga State Park on São Luis Island, and the Lencóis Maranhenses National Park, which is considered a wetland of international importance under the RAMSAR convention, and is also a Western Hemisphere Shorebird Reserve Network Site. In addition there are three environmental protection areas, an extractive reserve and a state park. However, it is not clear what percentage of these consist of mangroves.

Types and Severity of Threats

Over exploitation of the resources available in the mangroves of this ecoregion is a major threat. These mangroves however, are important to the subsistence economy of numerous artisanal fishermen, particularly for their abundance of crabs. In addition to fishing, mangroves are used as timber for construction of boats and houses, and their barks as a source of tannin used to dye ship sails. They are also used for firewood and charcoal. In some areas, mangroves have been converted to rice cultivation or to residential and industrial development, which has resulted in the extraction of forest products for industrial use, and the discharge of domestic and industrial wastes. The mangroves of Tutóia alone, which are near the Piauí border, were found to support 1,800 artisanal fisherman who caught 1,162 tons of shrimp in 1977. Other concerns are commercial fishing primarily for shrimp, and gold mining which has led to mercury contamination.

Justification of Ecoregion Delineation

Classification and linework for all mangrove ecoregions in Latin America and the Caribbean follow the results of a mangrove ecoregion workshop and subsequent report.

Additional Information on this Ecoregion

Further Reading

  • Diegues, A., Harris G., Moreira A.C. 1995. Marine region 9: South Atlantic. In: Great Barrier.
  • Reef Marine Park Authority, The World Bank, and The World Conservation Union. A global representative system of marine protected areas. Volume 2: Wider Caribbean, West Africa and South Atlantic. The World Bank Environment Department, Washington D.C.
  • Dunning, J.S. 1987. South American birds: a photographic aid to identification. Harrowood Books, Newton Square PA. ISBN: 0915180251
  • Ecoregional Workshop: A Conservation Assessment of Mangrove Ecoregions of Latin America and the Caribbean. 1994. Washington D.C., World Wildlife Fund.
  • Eisenberg, J.F. and K.H. Redford. 1999. Mammals of the neotropics: the central neotropics. Volume 3: Ecuador, Peru, Bolivia, Brazil. The University of Chicago Press, Chicago and London. ISBN: 0226195422
  • Frazier, Scott. 1999. Ed. A directory of wetlands of international importance designated under the Convention on Wetlands of International Importance (Ramsar, 1971). Compiled by Wetlands International for the Seventh Meeting of the Conference of Contracting Parties to the Ramsar Convention, San José, Costa Rica, May 1999.
  • Kjerfve, B., and L.D. Lacerda. 1993. Mangroves of Brazil. In: Lacerda L.D. ed. Conservation and sustainable utilization of mangrove forests in Latin America and Africa Regions. Part I: Latin America. International Society for Mangrove Ecosystems and the International Tropical Timber Organization.
  • Olson, D.M., E. Dinerstein, G. Cintrón, and P. Iolster. 1996. A conservation assessment of mangrove ecosystems of Latin America and the Caribbean. Final report for The Ford Foundation. World Wildlife Fund, Washington, D.C.
  • Pace Law School, 1998. Information sheet on Ramsar wetlands.
  • Rebelo-Mochel, Flávia. 1997. Mangroves on São Luís island, Maranhão, Brazil. In: Kjerfve, B., Lacerda, L.D. and Diop E.H.S. Mangrove ecosystem studies in Latin America and Africa. UNESCO, Paris France.
  • Schaeffer-Novelli, Y. 1999. (Consultora). Evaluation and priority actions for the conservation of the biodiversity of the marine and coastal zone. PRONABIO Projeto de conservação e utilização sustentável da diversidade biológica Brasileira - PROBIO. São Paulo, Brasil. Meio Ambiente.
  • Sick, H. 1993. Birds in Brazil: a natural history. Princeton University Press, Princeton NJ. ISBN: 0691085692
  • Ubiratan Moreira dos Santos, J., I. de Sousa Gorayeb, M. de Nazaré do Carmo Bastos 1999. Avaliação e ações prioritarias para a conservação da biodiversidade da zona costeira e marinha. Diagnóstico da situação para a conservação da biodiversidade da zona costeira e marinha amazônica. Ministerio do Meio Ambiente and Projecto de Conservação e Utilização Sustantável da Diversidadie Biológica Brasiliera. Belém, Pará,
  • Brasil. Base de Dados Tropical.


 

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

 

Glossary

Citation

Fund, W. (2014). Maranhao mangroves. Retrieved from http://www.eoearth.org/view/article/154453

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