Articles & Reports – Submerged Aquatic Vegetation

Topic Key

Submerged Aquatic Vegetation and Seagrass

 Ecological Importance

Future Predictions

Southeast Louisiana Focus

"There is a plethora of submerged aquatic plant species. Some may be more prevalent in certain areas than others. Submerged aquatic vegetation are plants that are completely under the water and typically have a root system in the bottom sediment. They require the water for physical support of the plant structure."

Neuston net after a trawl through a SAV bed. Photo by Jake Miller.

"Submerged aquatic vegetation (SAV) are underwater plants that grow in shallow water and do not emerge above the surface. These areas are important nurseries for juvenile fish and provide refuge for smaller species of fish and invertebrates from predators."

"Seagrasses are grass-like flowering plants that live completely submerged in marine and estuarine waters. Although seagrasses occur throughout the coastal areas of Florida, they are most abundant in Florida Bay and from Tarpon Springs northward to Apalachee Bay in the Gulf of Mexico, which are two of the most extensive seagrass beds in continental North America."

Seagrass beds off Virginia’s Eastern Shore went from barren sediment to abundant meadows in 20 years in the world’s largest restoration project. Photo Source: Jay Fleming

"The study is a blueprint for capitalizing on this habitat’s capacity to store carbon."

An otter resting over an eelgrass meadow. An otter floats above an eelgrass meadow.JOE TOMOLEONI/USGS

"These endangered predators enhance the genetic diversity of eelgrass, making their threatened seagrass surroundings more resilient."

Juvenile largemouth bass in submerged aquatic vegetation. Photo by Steve Luell

"Seagrasses are submerged flowering plants found in shallow marine waters, such as bays and lagoons and along the continental shelf in the Gulf of Mexico. A vital part of the marine ecosystem due to their productivity level, seagrasses provide food, habitat, and nursery areas for numerous vertebrate and invertebrate species."


"Surprisingly, minerals formed in restored seagrass beds can offset human-caused acidification miles away."

SAV growing in shallow water near Havre de Grace, MD. Credit: Will Parson/Chesapeake Bay Program

"Submerged aquatic vegetation is one of the most productive fish habitats on earth. We work to protect this important habitat, ensuring that it remains healthy and has a chance to thrive."

Photo Source: Catherine Smalley

"Hidden under the waves, the humble seagrass remains relatively unknown by many of us, but this unassuming-looking plant plays an important role in restoring the health of our coastal ecosystems and fighting the climate crisis. Discover more about this once-common marine plant and the vast seagrass meadows being replanted around the UK coast."

SAV in McReynolds Lake, 2002. Inset: Hydrilla verticillata

"Submerged aquatic vegetation (SAV or seagrass beds) are rooted, vascular plants that occur in shallow water across a broad range of salinity preferences. They are highly valuable in estuarine ecosystems due to the numerous ecological functions they perform."

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Despite the valuable role that mangroves and seagrass play in the Florida Keys ecosystem, these plants are facing one particularly large threat: Us.

In the Florida Keys, human development is the greatest threat to mangrove communities. Since the 1950s, more than 60 percent of mangroves in Monroe County have been destroyed for development. Activities such as dredging, using herbicides, and increasing waste water runoff have destroyed thousands of acres of mangrove habitat.

Queen Conch, Photo Credit: NOAA

"Submerged aquatic vegetation (SAV) includes aquatic grasses (seagrasses) and attached macro-algae. SAV is highly valuable habitat since it provides numerous important ecological functions that are difficult to replace; yet it is especially vulnerable to coastal development and water quality degradation."

Scholarly Research

Underwater grasses, also known as submerged aquatic vegetation (SAV), are seen at Round Bay on the Severn River in Anne Arundel County, Md., on Aug. 26, 2019. (Image by Will Parson/Chesapeake Bay Program)

"Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal human population pressures. Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions."

Eighteenth century map showing Lake Pontchartrain, Bayou St. John and other prominent bayous, in relation to the French Quarter and colonial settlement of New Orleans. Bayou Road runs from the French Quarter to Bayou St. John (F. Saucier, Carte Particulie’re du Cours du Fleuve St. Louis, 1749)

"A biogeographic study of submerged aquatic vegetation (SAV) in the Pontchartrain Basin of southeastern Louisiana was conducted. These plants provide numerous essential ecosystem services. Eighteen species occurred in different salinity zones ranging from freshwater to the saline waters of the Gulf of Mexico. Lake Pontchartrain SAV coverage was reduced by 70 percent from 1953 to 1990 due to increased turbidity from urbanization and shell dredging. A La Niña drought (1998–2001) increased SAV to 80 percent of the 1953 coverage, but declines occurred after the drought and there was extensive damage from Katrina and other hurricanes between 2005 and 2012."

Zooplankton are a diverse community of animals and a critical link in the Bering Sea food web. Credit: NOAA Fisheries.

"Submerged aquatic vegetation (SAV) plays important roles in shallow lakes. In addition to its refuge effect for zooplankton, one key role of SAV is to provide diverse ecological niches to these organisms. The reduction of habitat complexity due to loss of SAV might thus have huge effects on zooplankton communities. The objective of this study was to investigate the relationship between SAV abundance and composition and zooplankton functional diversity and community structure."

SAV in the Chesapeake Bay. Credit: Maryland Department of Natural Resources

"Coastal ecosystems are dynamic and productive areas that are vulnerable to effects of global climate change. Despite their potentially limited spatial extent, submerged aquatic vegetation (SAV) beds function in coastal ecosystems as foundation species, and perform important ecological services. However, limited understanding of the factors controlling SAV distribution and abundance across multiple salinity zones (fresh, intermediate, brackish, and saline) in the northern Gulf of Mexico restricts the ability of models to accurately predict resource availability.

(A)Map of study area within the Mississippi River Delta Plain. (B) Background map denotes potential submerged aquatic vegetation habitat area within the Mississippi River Delta Plain (C) Map denotes marsh zone designations (D) Site locations, distributed across submerged aquatic vegetation habitats

"Submerged aquatic vegetation (SAV) thrives across the estuarine salinity gradient providing valuable ecosystem services. Within the saline portion of estuaries, seagrass areas are frequently cited as hotspots for their role in capturing and retaining organic carbon (Corg). Non-seagrass SAV, located in the fresh to brackish estuarine areas, may also retain significant soil Corg, yet their role remains unquantified. Given rapidly occurring landscape and salinity changes due to human and natural disturbances, landscape level carbon pool estimates from estuarine SAV habitat blue carbon estimates are needed."

Location of study sites distributed acros Barataria Basin, Louisiana, USA. Inset (upper right) shows the location of Barataria Basin along the northern Gulf of Mexico, USA

"Spatial and temporal environmental variation control species distributions and abundances by defining habitat conditions that structure vegetation communities (Weiher & Keddy 1995, Wiens 2000). Describing this variation across multiple scales and identifying factors that control change remains a critical challenge for predicting vegetation communities and resulting habitat changes (Horne & Schneider 1995)."

Mean (± SE) organic carbon content of 20 cm cores from H. wrightii and T. testudinum natural seagrasses from 8 sampled Gulf of Mexico Sites vs. proximate previously-impacted seagrass meadow now barren. Significant differences (P < 0.05) among treatments and species are depicted with asterisks (*) according to a t-test.

"Seagrasses comprise a substantive North American and Caribbean Sea blue carbon sink. Yet fine-scale estimates of seagrass carbon stocks, fluxes from anthropogenic disturbances, and potential gains in sedimentary carbon from seagrass restoration are lacking for most of the Western Hemisphere."


"The ability of natural ecosystems to sequester significant amounts of organic carbon provides a good example of an ecosystem service that can be used in climate mitigation programs on local and regional scales. These mitigation programs may reduce the potential impact of increasing carbon dioxide concentrations in the atmosphere that are directly and indirectly driving climate change."



"Management is failing to adequately protect coastal ecosystems. Here we reviewed the policies, legislation, plans and management frameworks intended to protect seagrass meadows in 20 case-studies with the aim of identifying critical gaps in seagrass protection. The case-studies were chosen to represent a range of regions known to have high cumulative impacts or outstanding seagrass management"

"Seagrass restoration is a common tool for ecosystem service enhancement and compensatory mitigation for habitat loss. However, little is known about the long-term performance of these projects. We identified seagrass restoration projects by reviewing historic permitting documents, monitoring reports, and studies conducted in Florida, USA, most of which have not been cited previously in peer-reviewed literature. We then revisited 33 seagrass restorations ranging in age from 3 to 32 years to compare seagrass percent cover, species diversity, and community structure in restored and contemporary reference seagrass beds."

Lindsey Kilbride / WJCT News
Lindsey Kilbride / WJCT News

"To understand resiliency of submerged aquatic vegetation (SAV) communities with distance from the river mouth, SAV monitoring data, consisting of nine taxa, were analyzed in the lower St. Johns River, Florida, from 2001 to 2019. Patterns were evaluated with changes in salinity, turbidity, and weather events (e.g., hurricanes)."


"Seagrass meadows can be a powerful nature-based climate solution and help sustain communities hard-hit by stressors such as the COVID-19 pandemic, but these important ecosystems continue to decline."

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Michael A. Poirrier

"Although wigeon grass (Ruppia maritima) is common all along coastal Louisiana, true seagrass meadows containing turtle grass (Thalassia testudinum), manatee grass (Syringodium filiforme), shoal grass (Halodule wrightii), and star grass (Halophila englemannii) currently occur only east of the Mississippi River near the Chandeleur Islands (fig. 1)."