Didymo is a type of single‐celled, microscopic alga known as a Diatom. Diatoms have an outer “shell” of silica called a frustule. Some diatoms, like Didymo, can produce a stalk. Recently, enormous stalk production by Didymo has resulted in thick mats of Didymo in rivers worldwide and has generated concern because of possible impacts on the salmonid fish of these rivers. The Discovering Didymo Distribution project (D3) is a Canada‐USA collaboration that is being piloted in Alberta and in North Carolina and the southern Appalachians.


Volunteers participating in this project receive a sampling kit and training on how to collect and preserve samples and record their observations. To collect potential Didymo observations, participants are asked to use EpiCollect5, a free online citizen science application. EpiCollect5 allows us to build a crowdsourced database of potential Didymo observations containing data scientists can use, including maps and photos, while allowing participating anglers and citizen scientists to learn more about Didymo and where it is present. Volunteers are encouraged to sample their favorite rivers AND other rivers or small creeks where fish may or may not be present. Algae is scraped from rocks using standardized methods and stored in a specialized tube provided in the sampling kit. Other observations are recorded either using a datasheet or on a smartphone through the EpiCollect5 app and the sample is dropped off at drop‐off stations in Calgary, Lethbridge, Rocky Mountain House, or Red Deer. All samples are then shipped to the University of Calgary for analysis. Instructions for collecting samples and using EpiCollect5 as well as a paper datasheet are also included in kits or downloadable here.

For a map of Didymo observations and results of sample analysis following the 2017 season, click here. The web map now features sampling results from both the 2016 and 2017 D3 sampling seasons, as well as prior sampling efforts in Alberta and British Columbia by the University of Calgary in 2004, 2009, 2010, 2011, and 2013.

What’s Next?

Although this project is being piloted in Alberta and North Carolina, the project team plans to expand to other areas of North America in the coming years. In addition to expanding into new areas, resampling previous sampling sites to document changes in the presence or absence of Didymo would also be valuable. Following each sampling season, the web map will be updated to include the results of the analysis for samples collected and returned that season to enable the public to see where Didymo has been detected and where blooms have been documented.

Partners and Sponsors

This project began as a unique collaboration between Trout Unlimited Canada and Trout Unlimited in the USA. We currently are working with the University of Calgary with additional support and advice from Fisheries and Oceans Canada; the project is financially supported by the Alberta Conservation Association. The project is made possible by the many volunteers who collect samples and recorded their observations, and thanks to our project partners including the Oldman Watershed Council, Red Deer River Watershed Alliance, Lesser Slave Watershed Council, Milk River Watershed Council, Beaver River Watershed Alliance, Northern Lights Fly Fishers Chapter of TUC, the City of St. Albert, and students from the Olds College Land and Water Resources Program who collected a large portion of the samples in 2017 all across Alberta.