Chesapeake Bay Sentinel Site Cooperative researchers are working towards a better understanding of how the nation's largest estuary is changing over time due to rising sea levels. Scientists are collecting data with tide stations and other tools at sentinel sites around the Bay. Through intensive studies and long-term observations at these stations, Cooperative partners are helping to create a clearer picture of sea level and ecological changes in this region to better inform coastal decision-makers about the health of the Bay now and into the future.
"The success of the Chesapeake Bay Sentinel Site Cooperative can be traced to a dedicated group of scientists and managers interested in creating meaningful science syntheses that inform and guide decision-makers throughout the nation's largest estuary," says Sarah Wilkins, who coordinates the Chesapeake Bay Sentinel Site Cooperative as a Sea Grant extension specialist at the University of Maryland. "As a community of practice that shares lessons learned, advancements in the field, and best practices, we are beginning to understand how sea level rise and other environmental changes drive elevation gain and loss across vital Bay marshes."
When you think of sea level rise, you may picture the ocean rising slowly and uniformly around the world, just as water rises when filling a bathtub. But it's not that simple. While it's true that, on average, sea level is rising around the globe, sea level is changing at different rates in different regions on the local level as a result of several interacting processes. Some of these factors include global sea level rise caused by thermal expansion and melting glaciers; sinking of the land (subsidence) caused by groundwater extraction and geological processes; and the influence of oceanic and atmospheric dynamics, such as the El Niño Southern Oscillation.
The Chesapeake Bay—which experiences the highest rate of sea level rise on the Atlantic Coast—is a prime example of local sea level rise variability. In this region of the world, subsidence strongly influences local sea level rise. Long-term data from NOAA tide gauges positioned around the Bay indicate that relative sea levels are rising at 3.4 mm per year, or twice the average global rate of 1.7 mm per year. Over a 30-year period from 1985 to 2015, tide gauges showed rates of sea level rise ranging from 4.8 mm per year in flood-prone Annapolis, Maryland, to 6.3 mm per year at Sewell's Point, Virginia, in the Hampton Roads region.
Over 17 million people live within the bounds of the vast Chesapeake watershed. The estuary and its network of streams, creeks, and rivers hold tremendous ecological, cultural, economic, historic, and recreational value for the region. More than 250 fish and shellfish species use the Bay and tributaries for some portion of their life cycles, including American and hickory shad, river herring, striped bass, eel, weakfish, bluefish, flounder, oysters, and blue crabs. More than 300 migratory bird species can also be found in the watershed. With a better understanding of how sea level changes are affecting the Chesapeake, Cooperative partners are helping communities make informed decisions to keep the Bay healthy and sustainable.
Visit Maryland Sea Grant's website to learn more about this Cooperative, get contact information, and view/download a four-page brochure:
Water Levels: Sea level rise manifests itself differently along the coast, making it important to obtain local water level information. Water level monitoring stations at each sentinel site continually measure the depth of water, providing a long-term dataset for scientists to use.
Surface Elevation Tables: Surface elevation tables (SETs) are mechanical devices permanently installed in wetlands that allow scientists to measure small changes in surface elevation precisely and accurately. This tool allows scientists to better understand how coastal marshes respond to sea level rise. SETs are commonly used with marker horizons—squares of feldspar clay applied to the surface of the marsh—to track changes in accretion (the accumulation of sediments on the marsh surface over time).
Vegatation Sampling: Scientists measure plant traits such as height, percent cover, stem density, and biomass within sampling plots to understand how wetland vegetation responds to changing sea levels.
Water Quality: Water quality is a major driver
of ecosystem change. At water monitoring stations, researchers and managers monitor parameters such as temperature, total suspended solids, dissolved oxygen, pH, conductivity, chlorophyll, and nitrogen.
Meteorological Data: Real-time weather stations
at each sentinel site measure temperature, precipitation, wind speed, wind direction, relative humidity, and barometric pressure. This vital information helps scientists and managers understand estuarine circulation, plant productivity, and storm frequency and intensity.