Bivalve hatcheries across the U.S. frequently face unexplained production failures, or “crashes.” At the Horn Point Oyster Hatchery, we identified three microbial taxa— (i) Dinophyceae (dominated by Gyrodinium jinhaense), (ii) an unidentified mitochondria-like sequence, (iii) and a sequence related to Planctomycetaceae bacterium D2—that were more abundant in 3- to 5-day-old oyster larvae that later crashed than in successful batches (Figure 1A). The mitochondria-like sequence also preceded a crash in 2024.
To understand the ecology of these taxa in the surrounding environment, we analyzed their distribution across the Chesapeake Bay using existing data. The mitochondria-like ASV was linked to particles ≥5 microns and was found at only some locations, while the Planctomycetaceae relative and Dinophyceae were widespread (Figure 1B).
The size association of the mitochondria-like bacteria suggests it may be part of a toxin-producing algae or an endoparasite. Its limited distribution in the Bay suggests some hatchery crashes may result from its seasonal occurrence in nearby waters.