A discovery in the Anacostia watershed

Good morning, DMV! It’s Wednesday, Sept. 9.

Conservationists working to restore the Anacostia River and its tributaries were out conducting assessments when they spotted something growing on the floating baskets they use to culture mussels that help clean the waterways.

“I thought they were bryozoans … another filter feeder which originated in the ocean. We do have some freshwater bryozoans,” Jorge Bogantes Montero, the Anacostia Watershed Society’s natural resources program manager, told me on a call last week.

“Later, when I was in the Northwest Branch in Silver Spring, I saw this nice green [thing], I saw the holes, I said, ‘This might be a sponge.’ I put it on iNaturalist, and it was identified as a sponge. Just by comparing it with what I had seen on the mussel baskets, I realized we had sponges on the mussel baskets without knowing it.”

What is a freshwater sponge? Jorge wrote this explainer in a blog for the Anacostia Watershed Society:

This discovery — thanks to research supported by the Chesapeake Bay Trust — is in its preliminary phase and has launched a series of questions. So far, Jorge says, the team has found and identified seven species in the Anacostia watershed — which is about 176 square miles, mostly in Montgomery and Prince George’s counties in Maryland, and also in the eastern half of D.C.

The Anacostia Watershed Society is now continuing its research with Stephen Kolomyjec from the University of Olivet in Michigan and Mary Miller from the Louisiana Freshwater Sponge Project. They’ve been identifying the samples through microscopes and DNA analysis.

“We collected from all the main tributaries in the tidal river,” Jorge said, noting that there are about nine tributaries altogether. “Now we’re thinking: What is the next step with all these sponges?”

They aim to inventory the sponge species across the watershed. And they have a list of questions. What can sponges tell us about the river and its health? Could they be a good bioindicator to help experts understand water conditions? How tolerant are they to pollution? So far, he said, the sponges appear to provide “a complex snapshot.”

“We are finding them in streams that are pretty clean and streams that are challenged. So far it’s pointing toward a more nuanced picture, but we can understand better with the help of these experts.”

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Lydia Schwartz, 31, who lives on Capitol Hill, sent in this pic she took in the spring.

“I was walking down a trail at Sugarloaf Mountain this past May when I thought I saw a bright orange plastic toy from a few yards away,” she wrote in her submission.

“I went to pick it up, only to realize that it was alive! This red-spotted newt proved to be an excellent model and stood completely still throughout our 10+ minute photoshoot.”

Share your photos of life and wildlife in the DMV here.

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