Aquaculture America 2023

February 23 - 26, 2023

New Orleans, Louisiana USA


Taozhu Sun*, Michael Schwarz, Richard Snyder, Michael Congrove, Reza Ovissipour

Virginia Seafood Agricultural Research and Extension Center

15 Rudd Lane

Hampton, VA, 23669


Shellfish aquaculture, especially oysters, has provided valuable economic, ecological, and social benefits. Virginia is a leading producer of oysters along the U.S. Atlantic coast. In 2019, the aquaculture industry of Virginia produced more than $177 million for the commonwealth, while shellfish (e.g., oysters) contributed 84 percent of the total economic output. Oyster hatcheries are facilities that provide juvenile oysters for commercial production. The efficacy of larvae production in the oyster hatchery is primarily impacted by the utilized ambient water. However, many environmental factors can affect the quality and microbial safety of ambient water; a primary concern for oyster hatcheries is the loss of larvae due to disease outbreaks caused by bacterial pathogens, especially in the genus Vibrio. Therefore, developing innovations to ensure the quality and safety of ambient water is needed.

In this project, we have developed a prototype bioreactor system to clean and polish production water for direct reuse during oyster larval production. The system (as seen in the picture) can be integrated directly into standard hatchery operations, which include a typical drain/fill of larval tanks on a two-day cycle. Under standard operations, the larvae are usually resuspended in the water pumped directly from coastal waters or in a continuous supply culture system. While using our new technology, the water is sourced from a recirculating bioreactor. This bioreactor accomplishes converting nitrogenous wastes and organic material from microalgae and larvae. More importantly, it promotes the removal of fast-growing bacteria responding to larval culture, including potentially pathogenic bacteria (e.g., Vibrio spp.), by promoting populations of bacterivorous protists within the bioreactor. This technology supports bivalve hatchery operations “offline” when ambient water quality in coastal areas is impaired. Additionally, it remotes hatchery operations without direct access to surface water and out-of-season or head-start production.

The system is scaled up and in testing at a commercial hatchery currently. Water quality (e.g., temperature, dissolved oxygen, pH, salinity, total ammonia nitrogen, nitrite, nitrate, and alkalinity), seeds survival rate, and microbial analysis and community study (e.g., plate counts, DNA sequencing) were performed and evaluated. Our preliminary data indicated promising results compared to standard commercial single-use water management practices. Improved water quality and a significant reduction of Vibrio spp. were observed. The system has shown great potential in enhancing seed production consistency temporally, reducing reliance on coastal waters during poor ambient water quality, and providing improved options for out-of-season or early-season seed.