Environmental Engineering Reference
In-Depth Information
primarily due to competition for land for urban development, tourism, agriculture or
construction of ponds for shrimp farming. The high rate of negative changes in the
mangroves during the eighties in Asia, the Caribbean and Latin America has been caused
mainly by the conversion of these areas for aquaculture and infrastructure, as many
governments have opted for it with the intention of increasing security food, to stimulate
national economies and improve living standards. According to FAO, in 1980 the
mangroves covered a surface area of 19.8 million hectares of coastal areas of the world, for
the year 2005, the same FAO report 15.2 million hectares, which means that in the past 20
years have been lost 23% of the global area. With the pressures and if the trend continues,
we would be destroying one of representative ecosystems of global biodiversity (CONABIO,
2009). In Mexico, the annual loss rates calculated by comparing the mangrove areas are
between 1 and 2.5%, depending on the method of analysis of the information used (INE,
2005).
Magdalena Bay is one of the largest lagoon system in Mexico. The dense mangroves of the
bay represents the most extensive mangrove area of the Baja California peninsule (Enríquez-
Andrade, 1998, Hastings & Fisher, 2001; Malagrino, 2007), 21, 116 has been holding 85% of
mangrove state (Acosta-Velazquez & Vazquez-Lule, 2009), moreover, are of particular
importance because of its isolation from other areas of its kind. Here, the mangroves are
highly productive and structurally provide habitat, breeding sites and/or food for fish,
crustaceans, molluscs, sea turtles (López-Mendilaharsu
et al
., 2005) and birds (Zárate, 2007).
Particularly in these areas nesting a variety of both migratory and permanent residents
seabirds (Hastings & Fisher, 2001).
Regarding to marine fauna, it has been reported 161 species of fish in the bay, belonging to
120 genera and 61 families and four species of sea turtles (
Caretta caretta
,
Chelonia mydas
,
Dermochelys coriacea
and
Lepidochelys olivacea
) listed as endangered in NOM-059-
SEMARNAT-2001, gray whales (
Eschrichtius robustus
) under special protection and other
marine mammals can also be found within the Bay (Tena, 2010). The marine flora of the
lagoon system includes 279 species of macroalgae and 3 segrasses, for this reason it is
considered as a bay with high vegetation species richness (Hernández-Carmona
et al
., 2007).
Magdalena Bay is defined as an area with a high level of ecological integrity, the National
Commission for Biodiversity of Mexico, CONABIO recognizes the coastal area of
Magdalena Bay as a priority region for conservation from the standpoint of terrestrial,
marine, coastal and river basin hydrological as well as an Area of Importance for the
Conservation of Birds (AICA). In recent national studies the Magdalena Bay, has been listed
as a Site of Mangrove biological relevance and in need for ecological rehabilitation in the
North Pacific Region, PN03 site identifier Baja California Sur, Magdalena Bay (Fig. 4),
(CONABIO , 2009).
The most important plant community in the area is the mangrove. In Magdalena Bay exists
three of the four Mexican mangrove species: red mangrove (
Rhizophora mangle
) which is
endemic and is dominant in the area, associated with black mangrove (
Avicennia germinans
)
and white mangrove (
Laguncularia racemosa
).
These species are listed under the category of special protection in the Mexican Official
Standard NOM-059-SEMARNAT-2001. Mangroves are highly productive and structurally
provide habitat and breeding and feeding sites for fish, crustaceans, molluscs, turtles and
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