Delaware's SAV: Species Spotlights - WMAP Blog

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Delaware’s SAV: Species Spotlights

Written on: May 19th, 2023 in Natural Resources, Wetland Research

By Kayla Clauson, DNREC’s Watershed Assessment and Management Section

When you think of submerged aquatic vegetation (SAV), Delaware may not be the first state that pops into mind (we can’t be the first state all the time!) When SAV comes to mind, you may first think about the world-famous seagrass, Eelgrass (Zostera marina). In a marine environment, Eelgrass certainly runs the show being the only true seagrass in our region. However, there are a variety of other important species that exist in our less-salty waters. SAV can be found across different salinities, from saltier coastal oceans and bays, mixed estuarine rivers, and freshwater streams. In fact, as salinity of the water decreases, SAV species diversity increases!

*A freshwater submerged aquatic vegetation bed with multiple species. How many different species can you see?*

So, what makes SAV unique? Submerged aquatic vegetation is any rooted, aquatic plant that grows entirely underwater. Like terrestrial plants, aquatic plants even flower and produce seeds for pollination underwater. These aquatic plants are important because they improve water quality by filtering pollutants and even trapping sediments that improve water clarity. These underwater plants face different challenges compared to their terrestrial relatives. One of the main stressors in Delaware is turbid or murky waters, which limits the sunlight in the water column that is needed by plant’s to grow

This Elodea canadensis, or American waterweed, is seen with its flower stalk.

Although SAV is known to be important habitat, there have been minimal efforts to quantify what plants we have and where they exist in the First State. That’s why last year DNREC scientists began an official monitoring of SAV in freshwater streams across the state. Biologists visited 12 locations, looking at 9 different waterbodies and surveyed 6 miles of streams. These surveys documented 12 different species, with the most at the Brandywine Creek State Park. SAV beds ranged in size from dinner plates all the way up to a school bus! Among the beds were also various animals that benefit from SAV presence, including snails, freshwater mussels, and crawfish.

These survey results will be saved and added to more data collected this upcoming summer as DNREC works to catalog where and what SAV exists in Delaware. This information will help DNREC track SAV and work to increase populations of this beneficial plant community in the future.