tidal marshes

Salt Marshes And Climate Change | Earth Wise

May 5, 2023 By EarthWise Leave a Comment

Salt marshes are coastal wetlands that are flooded and drained by salt water brought in and out by the tides. These low-lying wetlands are also sometimes called tidal marshes because they occur in the zone between low and high tides. These wetlands are some of the most biologically productive ecosystems on Earth.

Cape Cod’s beautiful salt marshes are as important as they are iconic. They act as carbon sinks, protect coastal development from storm surge, play an outsized role in nitrogen cycling, and provide critical habitats for many fish, shellfish, and coastal birds.

According to scientists from the Marine Biological Laboratory in Woods Hole, Massachusetts, more than 90% of salt marshes around the world are likely to be underwater by the end of the century.

Since 1971, scientists from the Marine Biological Laboratory have mapped vegetative cover in Great Sippewissett Marsh in Falmouth, Massachusetts, to examine whether increased nitrogen in the environment would impact species of marsh grass. Because of the length of the study, the researchers were also able to investigate the impacts of climate change on the ecosystem, especially those driven by accelerating sea level rise.

The research team found that increased nitrogen favored higher levels of vegetation and accretion of the marsh surface. However, the researchers found that salt marshes will not be able to outpace the submergence from global sea level rise – no matter how much nitrogen is applied.

Sea level rise is the biggest threat to salt marshes around the world. Mitigating some of these projected losses is critical in order for salt marshes to continue to provide their important ecosystem services for people and the planet.

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Most of the World’s Salt Marshes Could Succumb to Sea Level Rise by Turn of Century

Photo, posted September 27, 2011, courtesy of Chris M Morris via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Blue Carbon Credits | Earth Wise

June 4, 2021 By EarthWise Leave a Comment

Carbon credits have been around since the late 1990s. The idea is to offset carbon emissions from some carbon emitting activity – anything from a wedding in California to a factory operating in Minnesota – by buying carbon credits earned from a carbon-absorbing activity, such as planting trees in the Amazon.

Blue carbon credits are credits earned by increasing the carbon stored in coastal and marine ecosystems. Coastal ecosystems such as mangroves, tidal marshes, and seagrass meadows in fact sequester and store more carbon per unit area than terrestrial forests and are increasingly being recognized for their important role in mitigating climate change.

Blue carbon credit awards have to date been relatively few and far between and have mostly been granted for mangrove restoration efforts. But mangrove projects are now ramping up dramatically in scope. Scientists are working hard to analyze the amount of carbon in other ecosystem types – seagrasses, salt marshes, seaweeds, and seafloor sediments – so that these systems can also enter the carbon credit market.

Over the past 20 years, conservation scientists have spread over 70 million seeds in the bays of Virginia to restore over 9,000 acres of seagrass meadows that were devastated by disease in the 1930s. The restored meadows are absorbing nearly half a ton of CO2 per acre.

The rules to allow for blue carbon credits are recent and evolving, which is a big deal. The market may currently be small, but it is growing exponentially. But as important as carbon credits are, it is still paramount to decarbonize before turning to offsets for existing emissions.

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Why the Market for ‘Blue Carbon’ Credits May Be Poised to Take Off

Photo, posted July 2, 2009, courtesy of Nicolas Raymond via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Hudson River Tidal Marshes And Sea Level Rise | Earth Wise

January 29, 2021 By EarthWise Leave a Comment

A new study at the University of Massachusetts Amherst looked at the resilience of Hudson River Estuary marshes to rising sea levels. They observed that these marshes are growing upward at a rate two or three times faster than sea level rise, suggesting that they should be resilient to accelerated sea level rise in the future.

The study documented the fact that more than half of Hudson River tidal marshes actually formed since 1850. In that year, the river channel was straightened, and a riverside railroad, berms, jetties and human-made islands of dredged soil were built. All of these human-made features trapped sediment and created backwaters that often turned into marshes.

The research centered on seven sites spanning more than 100 miles of the Hudson Estuary from Wall Street up to Albany. Although these marshes were an unintended result of early industrial development, they serve to protect the shoreline and provide rich ecosystems in terms of direct ecological and human benefits. Marshes are a first line of defense against coastal flooding, provide an essential habitat for juvenile commercial fish species, store huge amounts of carbon that mitigates climate change, provide habitat for migratory birds, and filter nutrients coming off the land.

The study determined that such marches form relatively quickly. When sediment is readily available, freshwater tidal wetlands can develop rapidly in sheltered settings. There is concern that marshes globally will be drowned by rising sea levels, but this Hudson River case study shows how marshes may be able to resist the rising seas. The research will help guide future land acquisition and land conservation strategies for areas adjacent to the river.

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New Study Finds More than Half of Hudson River Tidal Marshes were Created Accidentally by Humans; Resilient Against Sea Level Rise

Photo, posted December 4, 2008, courtesy of Daina Dajevskis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.