This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In 2025, a local crabber reached out to professor Romuald Lipcius with some news: He'd been catching stone crabs in the Chesapeake Bay. Native to Florida, the species had reached its northernmost documented occurrence to date.
News got out, and William & Mary's VIMS & Batten School were flooded with additional sightings from the public. Some were legitimate; many were mistaken identities. More recently, an egg-bearing stone crab was caught, providing evidence that the crabs aren't just visitors—they're reproducing in their new home.
Scientists refer to species expanding their range toward the poles as "climate migrants." Oceans are warming, and coastal estuaries like the Chesapeake Bay are warming even faster. Water temperature is only one shifting environmental factor, but it is a crucial one, influencing the reproduction and physiology of marine animals. With broad interdisciplinary expertise and a location on one of the nation's most ecologically productive estuaries, VIMS & the Batten School are positioned to understand what these changes mean for marine life.
Warming isn't occurring uniformly throughout the bay or across seasons, according to research led by former student Kyle Hinson, Ph.D. '23. Since the late 1980s, the bay has warmed three to four times faster in the summer than in winter, and bottom waters, where hypoxia is of greatest concern, have warmed by approximately 2 degrees Fahrenheit. Hinson and his co-authors in the Biogeochemical Circulation Ocean Modeling program found that atmospheric warming drives nearly 90% of the overall increase, while warming ocean waters play an especially important role near the bay's mouth.
Marine heat waves, or periods when water temperatures exceed the 90th percentile of historical temperatures for that time of year for at least five consecutive days, are increasing. Piero Mazzini and others in his lab have analyzed decades of data from NOAA's National Estuarine Research Reserve monitoring stations. Their research suggests the bay could experience marine heat wave conditions for approximately 100 days a year by the end of the century, compared with about 22 today.
Mazzini's work is helping to redefine our understanding of how heat moves through the water column, offering new classification systems for marine heat waves and providing a framework for assessing cumulative heat exposure. "Deeper down, the heat is slower to dissipate, and impacts on the surrounding ecosystem aren't fully known," he said. Warmer water holds less oxygen, which makes it likely that additional nutrient reductions will be necessary to offset the impacts of temperature increases on the bay's seasonal dead zone.
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