Led by School of
Marine Science Ph.D. student Nathan Shunk, the new study builds on 2022
research conducted by Piero Mazzini and Cassia Pianca that resulted in the
first comprehensive study of climatological aspects of marine heatwaves in the
Chesapeake Bay.
A dearth of data that
is both at the right frequency and over a long enough period means that little
is known globally about temperatures below the water’s surface during marine
heatwaves. For this study, Shunk and his
co-authors Mazzini and Ryan K. Walter (Cal Poly) explored data combined from
three different monitoring programs in the Chesapeake Bay — the National Data Buoy Center, the Center for Operational Oceanographic Products and Services and
the Chesapeake Bay National Estuarine
Research Reserve in Virginia — covering a
period from 1986 to 2021.
Subsurface temperature
data and other variables such as dissolved oxygen, available through the Chesapeake Bay Program, allowed the team to identify subsurface anomaly
profiles during marine heatwave events. Ultimately, they identified approximately
760 marine heatwave vertical profiles for use in their analysis.
“First of all, this
study would not have been possible without thirty years of steadfast efforts by
the various monitoring programs that collected the data we explored. So, I would
like to thank the researchers and staff that make the use of these datasets
possible,” said Shunk. “The most
surprising aspect of this analysis was that warming reached the bottom during
the winter. We expected the effects of these events to be limited to the
surface, like we found in the summer.”
The research shows
that marine heatwave events have very different impacts in the subsurface
depending on the season. Two regimes are documented: a “Homogeneous Season” and
a “Stratified Season.” During the “Homogeneous Season,” taking place in the
fall and winter, warming during marine heatwaves occurs throughout the entire
water column, influencing bottom organisms. During marine heatwaves in the
spring and summer “Stratified Season,” on the other hand, warming is only seen
in the near-surface and not the bottom.
Reflecting on the
value of the data used for the study, Mazzini said, “We are very fortunate to
have such a wealth of information provided through decades of immense effort of
data collection by the different monitoring programs in the Chesapeake Bay. I
hope the important results from our research inspire the creation of monitoring
programs in other estuaries worldwide.
Long term data sets like those now available in the Bay are crucial to help us
better understand climate change and its consequences, and guide future
management actions that will help to protect our marine and estuarine
environment for future generations.”