We see dozens if not hundreds of different plant species every day, from towering trees to colorful flowers to sturdy shrubs. Foliage is ubiquitous, and it plays an incredibly important role in ecosystems for humans and wildlife alike.

But how often do we consider underwater plants and the niches they occupy? While it can be easy to overlook submerged aquatic vegetation, one shouldn’t ignore this flora.

Submerged aquatic vegetation is a broad term that refers to sea- or baygrasses, which can grow in fresh, salt or brackish water, although they’re generally more attuned to lower salinity levels (no more than 5 parts per thousand). The vegetation is commonly mistaken for seaweed or algae, but it flowers and produces seeds, making these grasses more closely related to land plants.

“It’s a specific subgroup of aquatic plants that are fully submerged, so they’re rooted, flowering angiosperms that spend their whole entire lives underwater,” said Kayla Clauson, an environmental scientist with the Delaware Department of Natural Resources and Environment Control.

The vegetation varies in appearance, from long stems of grass to plants that resemble ferns or vines.

Submerged flora serves as vital habitat for many animals, such as bass, blue crabs and ducks, who use it as a sheltered space to raise young or as a source of food.

Unlike algae, submerged aquatic vegetation benefits water quality. Because underwater plants fill up the water column from root to stem, they help trap sediments, which leads to cleaner water. They also store nutrients like nitrogen and phosphorus and prevent harmful algal blooms by removing excess quantities of nutrients, although they’re still susceptible to the condition of the waterway. Too much algae or nutrient runoff can negatively impact water quality and even choke out underwater plants by blocking sunlight.

Submerged aquatic vegetation, specifically marine seagrass, is also very efficient at trapping carbon dioxide, a greenhouse gas produced in large quantities by human activities that contributes to climate change. This biological carbon sequestration is very valuable to our natural world and is one of the reasons DNREC launched the Submerged Aquatic Vegetation Program.

Housed in the DNREC Division of Watershed Stewardship, the program started in the spring of 2024, making it one of DNREC’s newer initiatives.

2024 also saw the official launch of the Delaware Statewide Submerged Aquatic Vegetation Workgroup, a team led by DNREC, Delaware Sea Grant, the Delaware Center for the Inland Bays and Partnership for the Delaware Estuary. The workgroup brings together nonprofits, academic institutions and entities from all levels of government as concerns underwater grasses. While DNREC and nonprofit partners were involved in some work in this area previously, the establishment of the program and the workgroup represent a shift to a more coordinated effort.

The team has established a set of priorities that guide its work, focused on permitting, public outreach, mapping, restoration and monitoring. Particularly key in these efforts are collecting data and educating Delawareans.

“One of the other big overall challenges is we just don’t have a full grasp of what we have and where we have it because we don’t have baseline data. And our efforts are starting to gather that, but at least compared to other mid-Atlantic states or states on the East Coast, we’re really behind on the data,” said Clauson, who runs DNREC’s Submerged Aquatic Vegetation Program.

Some personnel from the University of Delaware have been using sonar and environmental DNA to try and determine where unmapped submerged aquatic vegetation might exist in Delaware’s waterways.

The program and the workgroup are also engaged in small-scale restoration efforts in areas where submerged aquatic vegetation is known to grow.

Existing data suggests there’s a continuous band of marine seagrass stretching from North Carolina to Maine except for a break around the Delaware Bay. Exactly why the Delaware Bay differs greatly from the Chesapeake Bay, which is less than 100 miles to the west as the crow flies, is currently unclear, though Clauson speculated it could stem from our water being warmer and more opaque than the Chesapeake’s.

The plants are also affected by factors like how strong the current is and what the seabed is made up of. Some species are more tolerable of fast-moving currents, though they all generally need a substrate composed of sand or mud where they can anchor their roots.

Like almost everything else, submerged aquatic vegetation is impacted by climate change: The plants, especially ones growing in salt water, prefer cooler water.

Clauson noted some studies have observed population shifts to vegetation better able to tolerate warm water, though she cautioned these species may not necessarily have the same ecological niche.

DNREC established a facility in Lewes for research and restoration last spring. The site enables scientists to harvest and process seeds and conduct experiments to see how plants fare under different conditions and which are best suited for restoration.

DNREC hopes to gather more information in the coming years and has plans to expand outreach efforts, including starting a volunteer monitoring program where Delawareans can collect water quality data on behalf of the workgroup.

Familiarizing Delaware residents with the idea of submerged aquatic vegetation is an important item on Clauson’s checklist.

“When we’re looking at Maryland, it really is almost written into their culture. Most of the people that live on the Chesapeake Bay or the tributaries know about the grasses,” she said, noting research has been underway on the Chesapeake for decades.

More information on submerged aquatic vegetation, including details about different species found in Delaware, is available on the workgroup’s website.

Related Topics:  conservation, grass, nature, outdoor delaware, plants, science, Submerged Aquatic Vegetation, watershed, watershed stewardship