Partnership working to save wetlands

Blackwater National Wildlife Refuge on Maryland’s Eastern Shore is famous for its wintering waterfowl, bald eagles and vast tidal wetlands, which stretch as far as the eye can see.

But those marshes are falling apart, literally, as sea level rise overtakes their ability to build vertically on their own peat. As the roots of marsh plants become waterlogged, the plants lose vigour and patches of bare mud open up between them, eventually growing to form pools of open water which coalesce as the marsh soil erodes away.

In response, U.S. Fish and Wildlife Service has joined forces with the National Audubon Society and The Conservation Fund to implement an ambitious project to reverse this trend and prevent Blackwater’s wetlands from disappearing beneath rising tidal waters.

The project, completed in December 2016, transferred 26,000 cubic yards of sediment from the Blackwater River to the marsh surface in a process called “thin-layering,” with the goal of raising the surface of 40 acres of marsh to invigorate the growth of native marsh grasses. This is the largest wetland restoration project that has been attempted to date at Blackwater and the first thin-layer project in the Chesapeake watershed.

This project is important to saving the treasured marshes at Blackwater, which provide critical habitat for migrating birds and waterfowl and storm surge buffer for surrounding communities.

Scientists predict that, if no action is taken, virtually all of today’s tidal wetlands in the Chesapeake Bay will erode to open water by the end of the 21st century as sea levels rise at an ever faster pace due to the thermal expansion of the ocean’s waters.

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According to the Maryland Commission for Climate Change, the current best projection of sea level rise in Maryland is 3.6 feet by 2100.

“The marshes at Blackwater have been around for thousands of years” said Matt Whitbeck of the U.S. Fish and Wildlife Service, who is the supervisory biologist at Blackwater National Wildlife Refuge. “But they could disappear in the next few decades because of accelerating sea-level rise. If we lose these marshes, we also lose the unique salt marsh wildlife assemblage, thousands of acres of essential fish nursery habitat where juvenile fish can grow in safety from predators, and natural protection for local communities against storm surges during hurricanes.”

Blackwater Refuge is home to two bird species that are declining rapidly because of sea-level rise. The black rail was recently listed as endangered in the state of Maryland because a survey of this species in 2006 found it had declined more than 85 percent since the early 1990s.

The saltmarsh sparrow lives only in tidal salt marshes in the eastern United States. Its population, estimated at just 53,000, is declining at an alarming 9 percent per year.

However, these species no longer occur at the 40-acre restoration project site because of excessive flooding.

We’re catching this area of marsh in the nick of time. Between 2015 and 2016 the marsh surface has fragmented significantly. If we can extend the life of this marsh and demonstrate a technique that could help save the large wetland complex at Blackwater, then the project will be a success.

If we can also bring saltmarsh sparrows or black rails back here, that would be the icing on the cake.

The current wetland restoration at Blackwater is part of a suite of long-term strategies devised by a partnership of USFWS, The Conservation Fund and Audubon Maryland-DC to ensure tidal wetlands in and around Blackwater can persist in the face of climate-driven sea level rise.

The project is supported by a grant awarded to The Conservation Fund from the National Fish and Wildlife Foundation’s Hurricane Sandy Coastal Resiliency Competitive Grants Program, which allocated funds made available by the U.S. Department of Interior to 54 projects across the Northeast in the wake of the 2012 Superstorm Sandy.

David Curson is director of bird conservation for Audubon Maryland-DC, based in Baltimore.