Submersed aquatic vegetation (SAV) communities are highly productive ecosystems that provide significant ecological benefits within coastal areas, including support for many important species of fish and wildlife. Despite their critical importance, and loss globally, we lack consistent baseline data on SAV resources across the coastal salinity gradient. This project is part of a larger funded effort which has the overall objectives to document the occurrence and abundance of SAV resources (e.g., coverage, composition, seed resources) within the northern Gulf of Mexico over three years, to quantitatively assess environmental factors affecting SAV spatial and temporal variation, and to develop a conceptual model and maps of factors influencing SAV resources that can be used in predictive modeling. This portion of the project provides 2 years of coast-wide SAV data documenting percent cover, species composition, total biomass, and relating these to discrete water quality variables, nutrients, and landscape position.
We determined the distribution and abundance of SAV in 384 sites in nGOM coastal marshes in summer 2013 and 2014, and seed biomass in 2013. SAV resources were found to occur across the coastal zone, with approximately 20% of all sampled sites having SAV present. Salinity and water depth were the best predictors of SAV presence and biomass coast-wide, with more SAV resources in fresher marshes. As local SLR models predict altered salinities along the nGoM, these findings suggest concurrent changes in spatial distribution and abundance of seed and SAV resources for fish and wildlife. Understanding the drivers that influence SAV resources across salinity zones is critical to predict potential changes in coastal ecosystems in response to climate change
Additional funding acquired will be used to develop maps of SAV spatial distributions based on these data, and statistically identify models to predict changes in SAV resources with changing coastal salinities and water depths. This work will contribute to the refinement of existing models of ecosystem change and directly benefit efforts of the Gulf Coast Joint Venture (GCJV), Gulf Coast Prairies (GCP) Landscape Conservation Cooperative (LCC), and Gulf Coastal Plains and Ozarks (GCPO) LCC in forecasting the effects of these changes on distribution, abundance, and diversity of SAV resources and the priority fish and wildlife populations that depend upon them.
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