Location and General Description
This ecoregion encompasses a series of semi-continuous patches of mangroves in northeastern Brazil that extends from near Maceío southward to encompass Salvador Bay and one other mangrove outcrop slightly further south. This ecoregion covers a large length of coastline of at least Alagoas, Sergipe and Bahia States. Mangroves are associated with estuaries including those of the São Francisco, Sergipe, Paruguacu and Vaza-Barris Rivers. In the northern sector of the ecoregion, the climate is tropical semi-humid with a 4 to 5 month dry season. In the southern sector, the dominant climate is tropical humid without a dry season (Nimer 1979). Annual rainfall ranges from 1,250 to 1,500 mm.
The mangrove vegetation is 9 to 20 m tall and composed basically of three species: red mangrove (Rhizophora mangle), black mangrove (Aviccenia shaueriana), and white mangrove (Laguncularia racemosa).
Mangroves of the Rio São Francisco are well known for their wonderful surroundings where beaches, mangroves, and important patches of coastal restingas are found. Few detailed studies have been made on the biodiversity of this ecoregion, and no synthesis of biodiversity is available.
However, there is no doubt that mangroves of this ecoregion are crucial to several long-distance bird migrants including ruddy turnstone (Arenaria interpres), spotted sandpiper (Actitis macularia), and whimbrel (Numenius phaeopus) that utilize them as feeding and resting places from August through April during their extraordinary intercontinental journey (Sick 1993). In addition, a number of colonial birds such as great egret (Casmerodius albus), little blue heron (Egretta caerulea), and snowy egret (Egretta thula) use even the most disturbed patches of this ecoregion as nesting sites. Among the 5 species of sea turtles recorded in Brazil, at least 4 (Chelonya midas, Caretta caretta, Eretmochelys imbricata, and Lepidochelys olivacea) nest in the beaches of this ecoregion (Sanches 1999).
The Rio São Francisco mangroves are in good condition from a conservation viewpoint because there are several protected areas covering critical areas. The most important ones are the Areas of Environmental Protection of Piaçabuçu (91 km2) and Mangue Seco (34 km2), and the Biological Reserve of Santa Isabel (27 km2). The Santa Isabel reserve is the most important Brazilian nesting site of Lepidochelys olivacea.
Types and Severity of Threats
Critical mangroves near Aracaju and southern Sergipe (Area of Environmental Protection of Litoral Sul) are under high risk because of urban expansion, timber extraction, and pollution caused by agriculture and industry. Even given this situation, there are still lots of opportunities to build an efficient ecoregional conservation system to protect the biodiversity of the Rio São Francisco mangrove ecoregion.
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 (1994) and subsequent report (Olson et al. 1996).
Ecoregional Workshop: A Conservation Assessment of Mangrove Ecoregions of Latin America and the Caribbean. 1994. Washington D.C., World Wildlife Fund.
Nimer, E. 1979. Climatologia do Brasil. Rio de Janeiro: IBGE/SUPREN.
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.
Sanches, T.M. 1999. Tartarugas Marinhas. Report presented to the Workshop "Biodiversidade da Zona Costeira e Marinha". http:// www.bdt.org.br/ workshop/ costa/tartaruga.
Sick, H. 1993. Birds in Brazil: a natural history. Princeton University Press, Princeton.
Spalding, Mark, Francois Nlasco and Colin Field.1997. World Mangrove Atlas. Smith Settle, Otley, West Yrokshire, UK.
Stattersfield, Alison J., Michael J. Crosby, Adrian J. Long, and David C. Wege. 1998. Endemic bird areas of the World: Priorities for biodiversity conservation. BirdLife International. The Burlington Press, Cambridge, UK.
Prepared by: Jose Maria C. da Silva
Reviewed by: In process