A stone crab native to Florida has reached the Chesapeake Bay and begun reproducing there, according to reports that reached Romuald Lipcius, a professor at William & Mary's Virginia Institute of Marine Science and Batten School of Coastal & Marine Sciences. A local crabber first contacted Lipcius in 2025 with the catch, marking the species' northernmost documented occurrence. An egg-bearing stone crab was later caught, confirming the crabs are not just visitors but establishing populations in their new home.
The Chesapeake Bay is warming rapidly. Research led by former student Kyle Hinson found that since the late 1980s, the bay has warmed three to four times faster in summer than winter. Bottom waters have warmed by approximately 2 degrees Fahrenheit. Atmospheric warming drives nearly 90% of the overall increase, Hinson's team in the Biogeochemical Circulation Ocean Modeling program determined.
Marine heat waves are intensifying. Piero Mazzini's lab analyzed decades of monitoring data and projects that by century's end, the bay could experience marine heat wave conditions for approximately 100 days a year, compared with about 22 today. "Deeper down, the heat is slower to dissipate, and impacts on the surrounding ecosystem aren't fully known," Mazzini said.
Fish populations are shifting. Angelina Dichiera, a fish physiology expert at VIMS, studies how Chesapeake Bay fishes respond to warming and declining oxygen. "Benthic fishes that stay close to the bottom and do not expend as much energy when feeding may be able to acclimate better to gradual warming, whereas larger, faster-moving predators with higher metabolisms may have a lower tolerance for change and move away from the region," she said.
Fisheries surveys show southern species entering the bay, including gag grouper, juvenile southern flounder and juvenile bonefish. Cobia, red drum and speckled trout have become increasingly common in Virginia waters. A white shrimp fishery has emerged in Virginia coastal waters that did not exist a decade ago. Meanwhile, summer flounder have shifted farther north, and winter flounder, which once supported an important fishery, are rarely encountered.
Troy Tuckey, a VIMS fisheries scientist specializing in juvenile fish populations, cautioned that climate change is rarely the only explanation. "Fishing pressure, habitat, natural population cycles and other environmental factors are also changing." Decades of standardized monitoring data help distinguish long-term trends from unusual catches.
Habitat is shifting. Eelgrass, an important habitat-forming species, is increasingly giving way to widgeon grass in parts of the bay. Research led by Christopher Patrick suggests this shift could reverberate through the food web, since eelgrass supports greater animal biomass and larger prey for fish and blue crabs.
At the base of the food web, plankton responses matter. Nicole Millette studies how warming favors smaller plankton and certain phytoplankton including cyanobacteria and dinoflagellates associated with harmful algal blooms. Copepods, tiny zooplankton that feed on phytoplankton and become food for fish larvae, form a critical food web link. Changes in their abundance, size or nutritional value affect how efficiently energy moves to larger animals.
Disease patterns are changing. Ryan Carnegie, director of the Shellfish Pathology Laboratory, noted that Dermo, an oyster disease caused by the parasite Perkinsus marinus, has expanded northward as warmer temperatures and longer warm seasons have increased its activity. QPX, a disease affecting hard clams, is limited by warmer temperatures and could become less prevalent in Virginia as waters warm.
"There are so many factors at play at any given time, and they're all changing," Millette said. "That's just part of being in a dynamic, highly eutrophic, temperate estuary like the Chesapeake Bay."