New England salt marshes: so great, it’s Madness?

April 1, 2019

This past Monday, we hosted our latest Science Cafe, MarshMadness, showcasing the curiosities and intricacies of one of our favorite coastal habitats, the salt marsh. Marshes may not feature in this month’s basketball brackets, but our speakers made sure to highlight many reasons why studying, monitoring, and restoring salt marshes are slam dunks for coastal conservation.

Dr. Robert Buchsbaum of Mass Audubon kicked us off with the value of salt marshes, particularly those in Ipswich and the Great Marsh system here in Massachusetts. Salt marshes are a unique ecosystem, composed of very few (i.e. one or two) plant species in areas that are regularly submerged, since their conditions are harsh for most plants. As one of few plant species that can survive in both fresh and saltwater, and grow along dynamic coastlines, marsh grasses provide lots of important functions for healthy coastlines. They provide habitat for fishes and birds, remove pollutants (e.g. excess nitrogen from lawn fertilization) from the water before they reach the ocean, sequester carbon, and even support the harvest of salt marsh hay, a practice that has operated continually in MA for over 350 years! Unfortunately, our beloved New England salt marshes are subject to a triple threat. We’ve replaced many marshes with development along our coastlines. Purple marsh crabs have risen in numbers due to overfishing of their predators and have overgrazed the marsh. Excessive nutrients have reduced their roots and rhizomes, leaving them without a defense in the face of rising sea levels. All in all, it’s important to take a time out on these activities for the sake of our coastlines!

Dr. Akana Noto, a postdoc at the Marine Science Center, shared her research on grazing by the purple marsh crab on marsh plants. While marshes grasses flower and produce seeds, they typically reproduce by budding a new stem off of an existing rhizome (a hefty root structure), so a large patch of plants can be genetically identical clones. Akana wanted to know whether genetic diversity of plants (i.e. having plants from different sources in a small enclosure) influences how purple marsh crabs graze on the plants.  She brought a team of undergrads into a Cape Cod marsh to place enclosures on the marsh, and measure plant growth over time in the presence or absence of crab grazing. After the experiment was finished, she extracted DNA from the marsh plants to see how many different parental plants provided stems for each plot (i.e. how much genetic diversity was present in each plot). She found that those enclosures with more marsh plant genetic diversity grew more in spite of grazing by crabs. So, we might need to consider incorporating genetic diversity into salt marsh restoration to help the plants block and rebound from overgrazing and other stressors.

Barbara Warren, executive director of Salem Sound Coastwatch, rounded out our discussion with insights on marsh monitoring and steps we can take to protect our local marshes and improve coastal habitats. She talked about living shorelines which are designed to control erosion while incorporating natural elements in their design. With a living shoreline, water can be slowed down as it reaches the shoreline – think more dribbling around grass stems, less bouncing off the backboard (i.e. seawall). She called for volunteers to help with marsh planting and restoration efforts, and introduced some potential living shoreline projects and volunteer opportunities in Salem.

Our local New England salt marshes are so important to our environmental, cultural, and economic well-being. It really is #MarshMadness not to love and protect them! We hope you’ll join us for our next event, “Visualizing Oceans: from the Coasts to the Deep Sea,” coming to Down the Road brewery in Everett, MA, on April 9th from 6-8pm! Keep an eye on our website for future events, and if you’re local to Salem, don’t worry, we’ll be back at Gulu-Gulu in May.

  • Theresa

Theresa Davenport is a Ph.D. candidate in the Marine and Environmental Sciences department at Northeastern University. She is examining the benefits of coastal habitat restoration and exploring how restoration efforts can enhance ecosystem services.

Did you catch all “elite”* eight basketball puns? Tweet ‘em at us for a (virtual) high-five! @NUMarSci and @tdavenport83, using hashtag #MarshMadness! *Sorry, this one doesn’t count!

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