An Evaluation of Seagrass Community Structure and Its Role in Green Sea Turtle (Chelonia mydas) Forgaging Dynamics in the Lower Laguna Madre
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Satellite tracking data of juvenile and subadult green turtles captured and released by Texas A&M University at Galveston?s Sea Turtle and Fisheries Ecology Research Lab (STFERL) from the lower Laguna Madre indicate green sea turtles (Chelonia mydas) exhibit high fidelity to seagrass communities where they can be found year-round. Population growth is prerequisite to eventual down listing of this endangered species to a threatened status and its subsequent recovery. The role Texas? green turtle population will play in this recovery will depend, in part, on the ability of seagrass communities in the lower Laguna Madre to sustain continued growth of this population. Seagrass community structure was characterized during 7-8 March 2009 to determine if foraging grounds in the lower Laguna Madre can sustain green turtle population growth. Differences in seagrass community structure influencing foraging potential between high fidelity sites (Region 1) were compared to adjacent areas in which green turtles have not been captured and tracked by the STFERL (Region 2). Seagrass samples were taken from six seagrass communities to characterize seagrass and invertebrate community parameters. In addition, three standardized and randomized bag seine collections of nekton, invertebrates and plant debris were conducted within the six seagrass communities. Family richness and abundance of fishes and invertebrate fauna were assessed from the standardized bag seine collections. Seagrass species including Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass) were found in Region 1 whereas T. testudinum and H. wrightii were found in Region 2. Total seagrass biomass from Region 1 was significantly greater than that from Region 2 implying a healthier seagrass community. Seagrass beds in Region 2 were highly patchy and sparse. Family richness and faunal density collected with the bag seine in Region 1 were significantly higher than those in Region 2 suggesting seagrass habitat complexity was higher in Region 1. These data suggest a trend toward increased seagrass habitat quality and community complexity in Region 1 which, in turn, may contribute to a healthier seagrass environment that serves as an optimal foraging area for green turtles in the lower Laguna Madre.
Weatherall, Tracy F. (2010). An Evaluation of Seagrass Community Structure and Its Role in Green Sea Turtle (Chelonia mydas) Forgaging Dynamics in the Lower Laguna Madre. Texas A&M University. Available electronically from