On Sept. 29, 2021 NOAA announced that Downeast Institute was one of four institutions nation-wide awarded funding from Sea Grant and the Ocean Acidification Program to support research to address the impacts of multiple stressors on shellfish and increase resilience in shellfish aquaculture through research and industry partnerships.

Mussel aquaculture is a growing industry in Maine, especially as populations of intertidal wild mussels have declined, most likely due to high levels of predation spurred by increased ocean temperatures.  Additionally, early life stage bivalves are believed to be most vulnerable to ocean and coastal acidification and other environmental stressors.

DEI’s research, led by Dr. Robert Holmberg, was chosen to represent the New England region. The project will work to improve the resilience of hatchery-reared blue mussels to the interactive effects of ocean acidification and warming with diet enhancement and seawater buffering. From 2021-2024 Downeast Institute will test the efficacy of various alternative diet regimes to bolster mussel resilience to the stressors of ocean acidification and warming, as well as test for an interaction between diet enhancement and seawater buffering on both laboratory and commercial scales. We will work with two mussel farms, Bang’s Island Mussels and Blue Hill Bay Mussels, to complete grow-out trials.

There is evidence that diet plays an important role in the resilience of bivalves to the effects of ocean acidification and ocean warming, so this study will test how diet enhancement of larvae and young shellfish impacts survivorship and key growth metrics.This research seeks to fill the knowledge gap by testing whether diet enhancement can improve mussel resilience to ocean acidification and warming in the hatchery.

Hatchery Application

If successful, this diet mitigation strategy could easily be implemented by hatcheries. The strategy could complement existing protocols for seawater buffering, or even replace buffering where equipment for monitoring and controlling seawater carbonate chemistry is prohibitively expensive.

Community of Practice

This project also seeks to strengthen an existing community of practice composed of mussel growers and researchers at the Downeast Institute and the University of Maine. By co-producing a technology transfer and outreach plan, this team will help ensure the information generated by this project reaches the shellfish aquaculture community in Maine and beyond.


This work is funded by NOAA Sea Grant and the Ocean Acidification Program. The results will bolster NOAA’s Blue Economy Initiative by supporting U.S. seafood production and building coastal resiliency. Specifically, these investments support the goals of NOAA and the Department of Commerce and are consistent with Sea Grant’s focus area of Sustainable Fisheries and Aquaculture. Learn more about Sea Grant’s work in aquaculture and ocean acidification.

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