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Tidal Wetlands Abundance

As of 2005, there were approximately 283,946 acres of tidal wetlands.

July 22, 2011

What are waterfowl, and why is the Chesapeake Bay so important for these migratory birds? Mike Slattery from the U.S. Fish and Wildlife Service explains why waterfowl visit our region each winter and what is being done to protect their habitat.

Produced by Steve Droter
Music: “A Moment of Jazz” by Ancelin

July 22, 2011

A team of wildlife professionals is on a mission to eradicate the destructive, invasive rodent nutria from the Chesapeake Bay’s marshes. Steve Kendrot, wildlife biologist with the USDA Animal and Plant Health Inspection Service (APHIS), leads us on a journey through an Eastern Shore marsh to find signs of nutria, and explains why it’s so important for local landowners to support the eradication project.

Produced by Steve Droter
Music: “Demain je change de vie” by Löhstana David


In addition to being places of tremendous beauty, wetlands connect the land to the water. Throughout the Chesapeake Bay, these areas of transition provide unique habitats for a rich diversity of land animals and aquatic life.

Wetlands also act as sponges and natural filters by absorbing runoff and removing pollution from water before it enters streams, creeks, rivers and the Bay.

But the Chesapeake’s wetlands are fragile and threatened by shoreline development, sea level rise and invasive species.

Learn more about wetlands and wetlands restoration.


This indicator is used not to track progress toward a goal, but to measure how many acres of tidal wetlands are in the Bay and identify trends.

Assessment of the long-term data shows that there is a declining trend in tidal wetland abundance in the Chesapeake Bay. According to the land change statistics there was a 2,600 acre loss between 1996 and 2005. However, this change is not statistically significant at the Bay-wide scale due to limitations of the data.

While the changes are not significant on a Bay-wide scale, there are some significant changes on a local scale. Aerial photography in specific locations around the Bay has been used to visually document significant loss of wetlands. At Blackwater National Wildlife Refuge on Maryland’s Eastern Shore, scientists are documenting losses in wetlands due to sea level rise, land subsidence, coastal erosion and invasive species such as nutria.

Additional Information

Tidal Wetlands Abundance Indicator

This indicator is not intended to speak to the quality or health of the wetlands being analyzed; it is simply a quantitative tool.

This indicator uses a continuous source of Coastal Change Analysis Program (C-CAP) data available for the Chesapeake Bay region to determine the abundance of tidal wetlands in acres.

  • The C-CAP is a nationally standardized database of land cover and land change information developed by NOAA. It uses remotely sensed imagery for the coastal regions of the U.S.
  • C-CAP data consist of maps that identify the location of land cover changes that have occurred and a database that records the quantity and category of these conversions.
  • C-CAP products inventory on a one- to five-year cycle coastal intertidal areas, wetlands and adjacent uplands with the goal of monitoring these habitat.

This indicator will be improved over time. In the future, the Bay Program will have the capability to do high-resolution sampling verification of the C-CAP data.  There is also an effort underway by NOAA to analyze data from 1992 and 1984, which the Bay Program will be able to include in the indicator once available.

Ultimately, Bay Program partners hope to use this indicator as a tool to target management approaches in areas shown to be the most vulnerable to tidal wetland loss and conversion.

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