Investigation of water quality trigger points for Didymo Blooms in the Saint Marys Rapids, Lake Superior | W81EWF 23 SOI 0009

Opportunity Information: Apply for W81EWF 23 SOI 0009

The U.S. Army Corps of Engineers Engineer Research and Development Center (ERDC) is offering a cooperative agreement to build a collaborative, multi-year water quality monitoring program in the St. Marys River Rapids near Sault Ste. Marie, Michigan, adjacent to the Soo Locks and Dam (near the Saint Marys Powerhouse). The core purpose is to identify the water quality "trigger points" or physiochemical conditions that appear to precede or drive blooms of Didymo (Didymosphenia geminata), a stalk-forming freshwater diatom that can carpet river substrates and alter habitat. The monitoring results are intended to directly support follow-on ERDC and partner testing, including lab and field experiments designed to control, suppress, or otherwise manipulate Didymo growth once the most important environmental thresholds are better understood.

This opportunity is motivated by local ecological and economic risk. The St. Marys River supports a valuable commercial and recreational salmonid fishery and holds cultural significance for the Bay Mills Indian Community. Didymo was first detected in the St. Marys Rapids area in 2015, and there is concern that persistent or expanding blooms could reduce access to critical spawning habitat, degrade rearing conditions, and create recruitment bottlenecks for young fish by changing the availability of foraging habitat. While Didymo is considered native to some regions (including parts of Canada and Northern Europe) and has become established in areas of the Great Lakes, the specific environmental conditions that favor bloom initiation and productivity in this system are still not well defined, which is the key knowledge gap this project aims to address.

The work is structured as a tiered partnership between ERDC and an eligible Great Lakes-Northern Forest Cooperative Ecosystems Studies Unit (CESU) non-federal partner with strong local and technical expertise. ERDC will lead a continuous monitoring component by deploying and maintaining a YSI EXO2 data sonde in the rapids for a two-year period. That instrument will collect a continuous record of core water quality variables, specifically temperature, conductivity, dissolved oxygen, pH, and turbidity. In parallel, the CESU partner will run an ambient water sampling program near the deployed sonde to capture nutrient chemistry that cannot be fully characterized by the sonde alone. Sampling is planned weekly for much of the year, with an increase to twice weekly around the expected bloom onset and optimal growth period (noted as late May through early June) to better capture rapid shifts driven by weather and seasonal transitions.

The ambient sampling plan is fairly intensive and is designed to support statistical comparisons between water chemistry and biological bloom metrics. Each sampling event includes three replicate water samples to account for short-term variability and to improve confidence in measured concentrations. Samples are to be collected in coordination with local USACE support staff, preserved according to laboratory requirements, and analyzed for orthophosphate, ammonium, nitrate, total phosphorus, and total nitrogen. The solicitation emphasizes that the timing of discrete water samples needs to align closely with the continuous sonde record, because missing that overlap could prevent the project from detecting important relationships between nutrient conditions and the real-time physiochemical environment associated with bloom development.

Beyond chemistry, the CESU partner is also expected to monitor the rapids to document the status and progression of Didymo growth, linking field observations of bloom timing and magnitude (such as density or abundance) with the measured water quality record. At the end of each annual deployment, ERDC and the CESU partner will compile sonde and laboratory results into a shared database and jointly analyze the data to identify correlates between water quality conditions and Didymo biological responses. The local partner's watershed familiarity and experience interpreting biotic-physiochemical interactions is described as essential to making sense of patterns in a complex, dynamic river environment.

After two years of monitoring, the project transitions from observation to applied experimentation. Trends identified in the dataset will be used to design laboratory assays aimed at pinpointing parameter thresholds that appear to trigger or limit Didymo growth. The CESU partner will collect Didymo from the St. Marys River for propagation and use in lab testing, and may integrate findings into related efforts such as experimental stream studies. The end products include annual summaries of St. Marys Rapids water quality and a final report describing what was learned about how water quality relates to Didymo bloom behavior, with the broader goal of informing practical control strategies to protect habitat and the fishery.

Administratively, this is a discretionary science and technology/research and development cooperative agreement issued by the Department of the Army, U.S. Army Corps of Engineers, under authority 10 USC 4001. Award management is governed by federal assistance rules including 2 CFR 200 and 2 CFR 1100, along with Department of Defense research terms and conditions. A specific reporting requirement is that water sample data be transmitted to ERDC every two months, and the final deliverable is a comprehensive report analyzing how water quality conditions correlate with Didymo growth in the project area. Eligibility is restricted to non-federal partners of the Great Lakes-Northern Forest CESU. The posted award ceiling for this opportunity is $20,800, and the funding opportunity number is W81EWF 23 SOI 0009 (original closing date listed as 2023-07-17).

• The Dept. of the Army -- Corps of Engineers in the science and technology and other research and development sector is offering a public funding opportunity titled "Investigation of water quality trigger points for Didymo Blooms in the Saint Marys Rapids, Lake Superior" and is now available to receive applicants.
• Interested and eligible applicants and submit their applications by referencing the CFDA number(s): 12.630.
• This funding opportunity was created on 2023-05-25.
• Applicants must submit their applications by 2023-07-17. (Agency may still review applications by suitable applicants for the remaining/unused allocated funding in 2026.)
• Each selected applicant is eligible to receive up to $20,800.00 in funding.
• Eligible applicants include: Others.

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