Seagrass beds in the USVI are found in shallow bays with calm waters, and always associated with long sandy beaches that are protected from strong wave action. Seagrasses consist of a suite of photosynthetic marine plants that reproduce both vegetatively and through flowering and seed production (Williams and Heck 2001, Duffy 2006, Björk et al. 2008). In the USVI these habitats are important for various fish, invertebrates, and sea turtles.
Seagrass beds in the USVI have faced many threats. Hurricanes and storm surges can bury or uproot meadows, such as the two notable category 5 hurricanes Irma and Maria that occurred in 2017. Seagrass experience pressures from other climate related sources including sea level rise, ocean warming, sediment dynamic changes, and salinity regimes (VI EPSCOR, n.d.). Water quality can also be impacted by terrestrial erosion and sediment runoff, reducing light availability, and even smothering the seagrass bed entirely (Orth et al., 2006). Local seagrass beds are threatened by invasive seagrasses with the most prevalent being Halophila stipulacea, fast growing seagrasses outcompete natives especially after natural disasters such as the hurricanes. The invasive seagrass has potential to alter existing invertebrate and fish communities and to reduce wave dampening effects due to its smaller blades (Bryan, 2026).
Recent research has found that native seagrass presence significantly decreases with depth, while H. stipulacea was widespread across all depths surveyed. Although there is no confirmation of native seagrass presence at greater depths prior to surveying it demonstrates the expansion of seagrass habitat. The deeper habitat would also be less susceptible to threats such as storm surges and surface level warming. Which is potentially already being shown by the deep H. stipulacea habitat having significantly higher fish species richness, density, and diversity when compared to the shallow water H. stipulacea and mixed bed habitats (Rommelfanger et al., 2026).
While H. stipulacea may be outcompeting native species it may also be providing some benefits besides new deeper nurseries. A recent study exploring the importance of Blue Carbon storage in seagrass beds and particularly comparing H. stipulacea to native counter parts. The researchers found that carbon sequestered in the H. stipulacea sediment may store comparable amounts of carbon compared to larger native seagrasses present in the USVI (Vaughn et al., 2024).
In the USVI NOAA Benthic Habitat classification scheme and mapping initiative, Seagrass Beds are a subcategory under the submerged vegetation category. Seagrass beds are further divided by percent coverage.
Of the USVI SGCN, 15 rely on seagrass beds including six marine fish, seven marine invertebrates, one marine mammal, and one sea turtle. See table below for the list of these species: