Didymo

CALLICOON – Didymo, also known as Rock Snot, has been found in a 40 mile stretch of the Delaware River and that has the Delaware River Basin Commission concerned.

The invasive species has occurred before in the river, “but the spatial extent and intensity of this bloom is alarming given its potentially detrimental effect on ecosystems and the ease in which it can be spread to nearby tributaries,” said Dr. Erik Silldorff, an aquatic biologist with the DRBC.

He found didymo blooms extending from the area near the confluence with the Lackawaxen River downstream to the vicinity of Dingmans Ferry Bridge. That section of river includes portions of two National Park units – The Upper Delaware Scenic and Recreational River and the Delaware Water Gap National Recreation Area.

Following the discovery by Silldorff last week, scientists with the National Park Service and the Pennsylvania Department of Environmental Protection over this past week independently documented didymo blooms extending north of the area discovered by Silldorff to Callicoon as well as from Long Eddy upstream into the East and West branches of the Delaware River.

Didymo is not a public health hazard, but there is an ecological concern with discovering the invasive alga to the extent and concentrations found. DRBC officials said it can crowd out or smother more biologically valuable algae growing on the riverbed and significantly alter the physical and biological conditions within a stream.