BLACK MANGROVE TRANSPLANTAITON FOR SHORELINE STABLIAZATION IN THE BAHIA GRANDE WETLAND RESTORATION PROJECT, SOUTH TEXAS

The Bahia Grande is a shallow bay, off the lower Laguna Madre on the southernmost coast of Texas. It was a 6,700 acre of dried-out bay due to the construction of the Brownsville Ship Channel in the 1930's. It created not only an ecological wasteland but also resulted in a suspended dust problem to neighboring cities. A restoration project started in 2003 by a partnership between the U.S. Fish and Wildlife Service, Ocean Trust, the National Fisheries Institute, NOAA Restoration Center, and the EPA Gulf of Mexico Program. The hope of the constructed tidal salt-marsh is to restore the productive ecosystem of the Bahia Grande providing habitat and nursery for a variety of organisms.

Also, as part of the project was a revegetation project which included building of the Bahia Grande greenhouse on the University of Texas at Brownsville campus where native plants [Avicenna germinans (black mangroves)] and grasses are grown. The purpose is not only for esthetics but also for soil stabilization, ecological restoration by the establishment of habitat and to prevent the growth of invasive species.

Currently the Bahia Grande revegetation project is the growth stage, which should last until spring 2008. As the plan has been put into effect, problems have surfaced: due to the high evaporation rate of lower Texas the salinity in the artificial marsh have elevated to concentration even higher than that of sea water. This establishes high mortality rates for all living organisms including plants. Initial transplanting had less than 10% survival rates.

This study establishes the protocol for preparing plants for transplanting in this high salinity environment by systematically increasing the salinity for the black mangroves at the greenhouse. This experiment consisted of two experimental groups: one with a 5 ppt increase in salinity and another a 10 ppt increase in salinity every week. The black mangrove seedlings were transplanted bi-weekly to the Bahia Grande.