Cooperative Fish and Wildlife Research Units Program: Louisiana
Education, Research and Technical Assistance for Managing Our Natural Resources

DeMarco K, Hillman E, Couvillion B, Nyman JA, La Peyre MK. 2021.Defining aquatic habitat zones across northern Gulf of Mexico estuarine gradients through submerged aquatic vegetation species assemblage and biomass data


Submerged aquatic vegetation (SAV) creates highly productive habitats in coastal areas, providing support for many important species of fish and wildlife. Despite the importance and documented loss of SAV globally, we lack consistent baseline data on SAV resources across the estuarine gradient, particularly in northern Gulf of Mexico (NGOM) estuaries. To understand SAV distribution in the NGOM, SAV biomass and species identity were collected at 384 sites inter-annually (Jun-Sept; 2013-2015) from Mobile Bay, Alabama to San Antonio Bay, Texas, USA. Coast-wide, SAV distribution and biomass were consistent across years, covering an estimated 87 000 ha, and supporting approximately 15.5 ± 8.3% total cover with an average biomass of 24.5 ± 1.9 g m-2. Differences in hydrology (i.e., precipitation, freshwater input, water depth) and exposure (i.e., wave and wind energy) manifested in unique SAV assemblages and biomass distributions across the regional (i.e., Coastal Mississippi-Alabama, Mississippi River Coastal Wetlands, Chenier Plain, Texas Mid-Coast) and estuarine gradient (i.e., marsh zones defined as fresh, intermediate, brackish, saline). Mediod SAV species were associated with combined salinity, turbidity, and depth conditions unique to different region and marsh zone combinations in the NGOM. While the presence of SAV is often used as an indicator of ecological health, identifying mediod species in aquatic habitats can also be applied to describe estuarine conditions in more detail, and develop aquatic habitat zones. Exploration and use of this type of field data could be developed as means to track, manage, and define aquatic habitats across regional and estuarine gradients. Identifying aquatic zones through a representative mediod associates SAV species with locations defined by both long-term salinity and as well as salinity variability, water depth, and exposure and is a powerful potential tool for managers and restoration decision-makers.