Geographic Information Systems technology, specifically ArcView[R] and ArcGIS[R] software, was used to determine surface area of the three BMLC regions (i.
The BMLC is located on the Pacific coast of Baja California Sur, beginning ~900 km southeast of the U.
Offshore of the BMLC, the continental shelf is narrowest off Bahia Magdalena, with the shelf break (~-200 m) located only ~19 km from Boca Entrada (NIMA 1998).
The sedimentary composition of the BMLC consists primarily of fine to very fine sand, with appreciable amounts of lime and clay (Felix-Pico et al.
8 hours) in the BMLC is mixed semidiurnal, with periods of higher high water followed by those of lower low water, a condition that produces greater current velocities during ebb tides (Lankford 1977; Obeso-Nieblas et al.
The offshore region adjacent to the BMLC is considered a wind--driven upwelling system.
Surface temperature within the BMLC is consistently greater than that of adjacent ocean waters and is spatially and temporally variable.
Hydrologic conditions in the BMLC are hypersaline throughout the year as a result of low precipitation, the typical absence of fresh water input, and a high rate of evaporation.
The BMLC region is part of the Sonoran Desert, and the climate characteristically varies from temperate to hot and is very dry (Garcia 1973; MacMahon 1997).
Most of these authors, however, consider the BMLC to representa transition zone between warm-temperate and tropical species (e.
Many tropical species extend north of the BMLC for a considerable distance, inhabiting shallow, protected bays and inlets, whereas warm temperate species are found in nearshore coastal regions and cool temperate species are associated with upwelling areas (Garth 1960; Hubbs 1960).
White (Laguncularia racemosa), red (Rhizophora mangle), and black (Avicennia germinans) mangrove species are present throughout the BMLC (Nienhuis and Guerrero-Caballero 1985; Garate-Lizarraga and Siqueiros-Beltrones 1998; pers.