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Identification of Priority Sites for Conservation

in the Northern Gulf of Mexico an Ecoregional Plan The Nature Conservancy, DRAFT - August 2000

The aim of this work was to identify sites within the northern Gulf of Mexico ecoregion that if protected would fully represent the biological diversity of the nearshore waters of this region.

The northern Gulf of Mexico ecoregion extends from

of the Laguna Madre Louisianian Province.

de Tamaulipas, Mexico, a It is a rich and productive

Anclote Keys, FL to the southern extent region which is also identified as the subtropical environment that supports

extensive wetland and seagrass habitats. Much of the nearshore divided into bays and estuaries behind barrier islands, which form a northern Gulf of Mexico.


of the Gulf

ring of

sites around

are the

The northern Gulf of Mexico is divided into three broad subregions: the western subregion extends south from Galveston Bay; the central subregion is from Galveston Bay, TX to Mobile Bay, AL; and, the eastern subregion encompasses the northwest Florida coast The western subregion is characterized by low freshwater input, sandy sediments, and clear waters; ideal conditions for the growth of seagrasses. In general, freshwater input decreases southward, and in the southern portions of this subregion evaporation is greater than freshwater input.

These conditions in combination with shallow the hypersaline bays of the Laguna Madre

waters limit exchange with the Gulf and create








embayments Salinities are waters (34-35

of the Laguna Madre comprise the generally much higher, 35-70 parts ppt).

largest hypersaline lagoon in the per thousand (ppt), than typical

world. marine

As a preliminary goal, it was decided that the network of priority sites should contain at least 20% of the current distribution of each habitat and imperiled species target in each subregion. It was also decided that potential sites should generally encompass entire bays and estuaries as landscape-scale sites. These estuarine landscapes are assemblages of many species and communities with dynamics that are tied to variability in salinity (and associated physical- chemical conditions) created by the interaction between freshwater drainage and tidal influx.

Two primary tools were used to choose a set of high priority sites for conservation (i) a reserve selection algorithm, Sites v1.0, and (ii) expert interviews and an expert’s workshop. The final portfolio of sites integrated information on the known distribution of targets and information provided by many local experts. As part of the assembly process, we also identified some high priority sites (= action sites) contained within the priority bays and estuaries. These high priority sites encompassed the best examples of the conservation targets in the northern Gulf of Mexico.

A preliminary analysis was done at the priority sites to assess the likely stresses to the conservation targets. It is likely that the importance of some of the stresses and their sources will be revised upon closer examination during the more detailed process of site conservation planning.

The following list includes the targets for the western subregion: Primary habitat targets Seagrass, Tidal Freshwater Grasses ,Oyster reefs, Salt marsh Tidal Tidal Fresh Marsh Flats, Intertidal Scrub/Forest Secondary habitat targets: Muddy -bottom Habitats, Coquina Beach, Rock Beaches & Bars, Intertidal/subtidal beaches & bars, Serpulid Worm Reefs. Imperiled Species: Kemp's ridley Turtle, Texas pipefish, Opossum pipefish, Dwarf seahorse, Diamondback Terrapin.


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