The small motorboat anchors in the middle of the Chesapeake Bay. Shrieks of wintering birds assault the vessel’s five crew members, all clad in bright orange flotation suits. One of the crew slowly pulls a rope out of the water to retrieve a plastic tube, about the length of a person’s arm and filled with mud from the bottom of the bay. As the tube is hauled on board, the stench of rotten eggs fills the air.

“Chesapeake Bay mud is stinky,” says Sairah Malkin, a biogeochemist at the University of Maryland Center for Environmental Science in Cambridge who is aboard the boat. The smell comes from sulfuric chemicals called sulfides within the mud. They’re quite toxic, Malkin explains.

Malkin and her team venture out onto the bay every couple of months to sample the foul muck and track the abundance of squiggling mud dwellers called cable bacteria. The microbes are living wires: Their threadlike bodies — thinner than a human hair — can channel electricity.

Sairah Malkin looks at a sediment core tube on a boat in the Chesapeake Bay

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