Severn River Association launches SAV Navy to monitor underwater grass

Rachael Pacella
Contact Reporterrpacella@capgaznews.com

Dave Gertz lives on Valentine Creek on the Severn River, in a house that he inherited from his great-grandfather.

Growing up, his great-grandfather told him about the underwater grass that grew near the home, but disappeared within his lifetime. Gertz has seen the grass again in recent years; it piqued his interest, and now he wants to help preserve it.

Ted Delaplaine lives on Little Round Bay and sometimes sees underwater grass growing outside his house. He wondered how it is doing.

They are two of roughly 25 volunteers who have signed up for the Severn River Association's Submerged Aquatic Vegetation Navy.

The SAV Navy will be hunting down underwater grass and marking its location using GPS now through mid-August, when the grass will start dying off for the season.

The new effort is in its infant stages — this first year will be a wet run, said organizer Tom Guay.

Underwater grass is an indicator of overall water quality, Guay said, and it also serves as habitat for young fish and crabs who need to hide from predators. The SAV Navy will determine what type of grass is growing in the Severn and how large the beds are.

The Severn River Association is one of four groups in the Chesapeake Bay watershed which received funding from the Chesapeake Bay Program to survey underwater grass, according to Brooke Landry, a Maryland Department of Natural Resources biologist who chairs the program's SAV work group.

So far with roughly $12,000 in funding, Guay has purchased buckets with clear bottoms, GPS devices, waterproof cameras, phone cases, rakes and Secchi discs to read water clarity. He has assembled kits with those materials, which he is giving to the volunteer scientists who have agreed to help record nine underwater grass beds in the river.

The volunteers will travel above the underwater beds by kayak or paddle board and use a GPS device or cellphone to record the edges of the beds, which will help determine their exact size. The density of grass throughout the bed will also be measured.

Volunteers will use rakes to pull up and identify the species of grass growing underwater. They'll also make observations, such as how clear the water is and whether the shoreline near the grass is natural or hardened by rocks or bulkheads.

They can also take photos of the grass they find and share it with others using a social media application called Water Reporter. Landry said some bay program funding also went to the app's developer so they could expand the platform to include SAV survey information and reporting.

SAV Navy members tested their equipment July 11 at a beach at Winchester-on-the-Severn, and will now head out on their own to collect information. The volunteers who came to test the equipment were eager to start the project — Delaplaine swam into the water near a jetty searching for grass. He didn't find any, however.

For many, involvement in the grass survey is driven by curiosity.

"I'm very curious to know how our sea grasses are doing, and I figure since we live right there and occasionally have the grasses, it'd be a natural thing to try to help out," Gertz said.

The effort will help an annual aerial grass survey conducted by the Virginia Institute of Marine Science. From the air, researchers can see where the grass is growing and how much of it there is, but that doesn't tell them exactly what species is growing or the conditions on the ground.

The citizen science effort should help provide that information and verify the findings of the aerial survey, which has been conducted for more than three decades.

In a paper co-authored by aerial survey leader Robert Orth and published in the journal BioScience this June, bay grass is described as a "sentinel species." The grass is an indicator of water quality, and it's also an environmental defender, protecting shorelines from erosion and providing habitat for juvenile fish and crabs.

"Overall the numbers indicate that SAV has done better in the past couple years," Orth said in an interview, talking about the entire Chesapeake Bay.

In the 2016 VIMS survey, 311 acres of grass were found in the Severn River, an increase of 34 percent from 2015. Andrew Muller, an oceanography professor at the Naval Academy and a Severn River Association board member, said that's about 68 percent of the historic level of grass in the river.

Most of the grass in the Severn River is in the area of Round Bay. The sandy bottom on the edges of the bay and better water clarity are factors for better grass growth in that region, Muller said.

The 2016 aerial survey found 97,433 acres of grass in the bay as a whole — that is an 8 percent increase in regions mapped in both 2016 and 2015. Some parts weren't mapped in 2016 because of weather and security restrictions, and the bay program estimates that the baywide total would be at least 99,409 acres if all regions were mapped in 2016.

That estimate is 54 percent of the Chesapeake Bay Program's restoration goal of 185,000 acres.

"We are seeing a positive upward trend for (submerged aquatic vegetation) in the bay," Landry said.

Landry said it's hard to know for sure, but hopefully the positive trend is the result of total maximum daily load limits for nitrogen, phosphorus and sediment, which were put in place by the U.S. Environmental Protection Agency in 2010.

In the Severn, Muller thinks cooler water temperatures along the main stem of the river in recent years may be contributing to the increase in grass.

In addition to assisting the aerial survey, the project is also designed to get residents connected with the waterways they live near.

"We're trying to engage all the people who live in the community to get out, muck around in the water, identify underwater grasses so they can understand the value of it, too, and explain it to their neighbors and kids," Guay said.

Landry said the program will help people get out, fall in love with the water and recognize the importance of submerged aquatic vegetation.

If you would like to volunteer for the SAV Navy, visit www.facebook.com/SRAOnTheRiver or www.severnriver.org.

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