Louisiana Project: Occurrence and variation in submersed aquatic vegetation along the northern coast of the Gulf of Mexico

Louisiana Project

Occurrence and variation in submersed aquatic vegetation along the northern coast of the Gulf of Mexico

September 2012 - August 2020

Personnel

Megan La Peyre, Principal Investigator

Participating Agencies

FWS, Gulf Coast Joint Venture
SSP program
National Park Service
GCPO LCC
South Central Climate Center

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 will provide data on the occurrence and abundance of SAV resources (e.g., coverage, composition, seed resources) within the northern Gulf of Mexico, quantitatively assess environmental factors affecting its spatial and temporal variation and develop a conceptual model of factors influencing SAV resources. These data are critical in identifying empirical relationships between SAV resources and environmental variables, and will enable predictive modeling of SAV resources under different scenarios of landscape and climate change.

Research Publications

Research Publications	Publication Date
La Peyre, MK. 2015. Final Summary to the South Central Climate Science Center for Occurrence and variation in submersed aquatic vegetation along the northern Gulf of Mexico: a hierarchical approach to assess impacts of environmental change on SAV resources. 2012-2015.	December 2015
Hillmann, E., K.E. DeMarco and M La Peyre. 2016. Establishing a baseline of estuarine submerged aquatic vegetation resources across salinity zones within coastal areas of the northern Gulf of Mexico. Journal of the Southeastern Association of Fish and Wildlife Agencies. 3:25-32. \| Abstract \| Publisher Website	August 2016	Coastal ecosystems are dynamic and productive but vulnerable to changes associated with global climate change. Despite their limited areal extent, submerged aquatic vegetation (SAV) exists in coastal ecosystems as foundation species and performs important ecological functions including provision of habitat and food resources. However, limited understanding of factors controlling SAV distribution and abundance within the extensive fresh to saline coastal habitats along the northern Gulf of Mexico (nGoM) restricts the ability of models to accurately predict resource availability. We sampled 384 potential coastal SAV sites across the nGoM in 2013 and 2014, and examined community and species-specific SAV distribution and biomass in relation to year, salinity, turbidity and water depth. After two years of sampling, 14 species of SAV were documented, with three species (Ceratophyllum demersum, Myriophyllum spicatum, Ruppia maritima) accounting for 54% of above-ground biomass collected. Total aboveground SAV biomass was higher in fresher habitats as compared to saline habitats and salinity and water depth were dominant drivers of species assemblages. Changes in salinity and water depths predicted by climate change models for the northern Gulf of Mexico coast will likely alter SAV production and species assemblages; these changes may affect habitat and food resources for dependent faunal species. Understanding the environmental drivers that influence SAV distribution across salinity zones will ultimately enable more accurate predictive modeling and management of SAV resources under different scenarios of restoration and climate change.
DeMarco, K, E. Hillmann, M. Brasher, M. La Peyre. 2016. Brackish marsh zones as a waterfowl habitat resource in submerged aquatic vegetation beds in the northern Gulf of Mexico. Journal of the Southeastern Association of Fish and Wildlife Agencies 3:261-269. \| Abstract \| Publisher Website	March 2016	Submerged aquatic vegetation (SAV) beds are prevalent in shallow coastal habitats that are increasingly exposed to sea-level rise (SLR) effects. In the northern Gulf of Mexico (nGoM), an area particularly vulnerable to SLR, the abundance and distribution of SAV food resources (seeds, rhizomes and tissue) can influence the carrying capacity of coastal marshes for waterfowl. Despite the documented importance of SAV within coastal ecosystems, and specifically to waterfowl, little is known about their distribution across coastal landscapes and salinity zones, or the potential impacts of SLR. We estimated SAV cover and seed biomass in coastal marshes from Texas to Alabama in summer 2013 to assess variation in SAV and seed resource distribution and abundance across the coastal salinity gradient. Coast-wide, SAV percent cover was similar between all salinity zones (10-20%) however patterns of distribution differed between salinity zones. Specifically, saline sites were characterized by fewer sites with SAV, but sites with SAV had greater percent cover as compared to fresh, intermediate and brackish zones. Coast-wide means for seed biomass were highly variable, and not significantly different across salinity zones although waterfowl forage availability was lowest in saline zones (<0.5 g m-2) as compared to fresh, intermediate and brackish zones (>1.2 g m-2). As local SLR models predict altered coastal marsh types are likely along the nGoM, these findings suggest concurrent changes in spatial distribution and abundance of SAV and seed resources. If trends identified here are persistent across the coast, SAV resources available for waterfowl may be similar among fresh, intermediate and brackish marsh types.
De Marco, KD, Couvillion, B, Brown S., La Peyre, MK. 2018. Submerged aquatic vegetation mapping in coastal Louisiana through development of a spatial likelihood occurrence (SLOO) model. Aquatic Botany 151:87-97.	September 2018

Technical Publications

Technical Publications	Publication Date
La Peyre, M., DeMarco, K., and Hillmann, E., 2017, Submerged aquatic vegetation and environmental data for coastal areas from Texas through Alabama, 2013-2015: U.S. Geological Survey data release, https://doi.org/10.5066/F7GH9G44.	May 2017
Hillmann, E., and La Peyre, M., 2017, Sediment carbon, submerged aquatic vegetation and environmental variables in deltaic southeast Louisiana (2015-2016): U.S. Geological Survey data release,https://doi.org/10.5066/F7QZ2853.	May 2017
Hillmann, E., DeMarco, K., and La Peyre, M., 2017, Submerged aquatic vegetation and environmental data along a salinity gradient in Barataria Bay, Louisiana (2015): U.S. Geological Survey Data Release, https://doi.org/10.5066/F7M61HG4.	May 2017
DeMarco, K., Hillmann, E., and La Peyre, M., 2017, Seed biomass from shallow coastal water areas from Texas through Alabama, 2013-2015: U.S. Geological Survey data release,https://doi.org/10.5066/F7Z899WV.	May 2017
DeMarco, K., Hillmann, E., and La Peyre, M., 2017, Seed biomass from shallow coastal water areas along a salinity gradient in Barataria Bay, Louisiana (2015): U.S. Geological Survey data release, https://doi.org/10.5066/F7TH8K5J.	May 2017

Theses and Dissertations

Theses and Dissertations	Publication Date
Hillmann, ER. 2018. Analysis of submerged aquatic vegetation across the northern Gulf of Mexico: Communities and Biomass. PhD Dissertation, Louisiana State University, Baton Rouge, LA	May 2018
DeMarco, KD. 2018. Shifting ecological niche across coastal landscapes: spatial and temporal ecological patterns driving submerged aquatic vegetation habitat distribution across the northern Gulf of Mexico. PhD Dissertation. Louisiana State University, Baton Rouge, LA.	August 2018

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