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Citizen’s River Monitoring Program

What is Didymo or “Rock Snot”?

Didymosphenia geminata is the scientific name for didymo. Didymo is considered an invasive and nuisance diatom species. This diatom species has copious mucilaginous polysaccharide stalks that persist even after their microscopic cells die. The cell itself isn’t what creates the nuisance, it is the stalks. It was originally deemed a nuisance in 2005 because of the didymo “bloom” (grew in biomass) in New Zealand which caused massive die-offs of other organisms. Aesthetically, it is not a pleasant sight since it inhabits the substrate of rivers and has the appearance of “rock snot”. Except for some minor eye irritations, didymo isn’t considered a health risk to humans though it does have an impact on fish and the river ecosystem. It can impact recreational fishing, kayaking and swimming too.

Major objectives are:

  1. Survey the West Branch of the Farmington River for Didymosphenia geminata and Cymbella janischii and other “rock snot” diatoms.
  2. Survey the angler community to help determine anglers fishing habits such as cleaning their boots and gear
  3. Implement a “Citizen’s River Monitoring Program” website that students from Three Rivers Community College will use to monitor.
  4. Provide DNA barcoding and morphological analysis to better understand these diatoms.
  5. Contribute DNA sequences to GenBank to help expand the diatom DNA database.

What to Do If You Suspect You Have Seen Didymo

If you think you have seen didymo please submit a report using the form link below and provide photos. Provide samples only if the rock snot is NOT GREEN and it looks like some of the photos on this website. Place the sample in a plastic zip-lock bag and mail it to us at Three Rivers Community College in care of Diba Khan-Bureau. Make sure the sample is moist and NOT wet or saturated for mailing purposes.

On the map link below we will post yellow pins of any suspected cases, red pins if confirmed, and green pins if suspected areas were determined not to be Didymo. Sample microscopic and other images can be seen via the Sample Images link. You can submit any suspected cases of Didymosphenia geminata to Three Rivers Community College for testing via the form link. We may also ask you to mail us a sample to have it analyzed and confirmed at the College.