NPS What are marshes?At the simplest level, marshes are a wetland ecosystem characterized by grasses that are adapted to regularly flood at high tide. Marshes grow wherever land meets water all around the Chesapeake Bay and its tributaries.What do marshes do?The grasses that make up marshes are what scientists call "ecosystem engineers", meaning they create habitat for other species in the ecosystem. Marsh grasses accomplish this in a multitude of ways, their roots act as nurseries and a food source for young fish to take shelter from predators while they grow, osprey and herons stalk the waters for prey, muskrats and river otters make their homes in the thick stands of grass, waterfowl migrate to these ecosystems to winter. Most iconic Chesapeake species such as rockfish, blue crabs and blue herons are reliant on marshes for at least part of their lifespan. As ecosystem engineers' marsh grasses also improve living conditions for species in the ecosystem, which is accomplished primarily by acting as a filter for pollutants as they enter the water. Since marshes grow on the water's edge that means that all rainwater must pass through the marsh before entering the waterway, marsh grasses have shown a remarkable ability to absorb excess nutrients before they enter the water way, preventing algal blooms and dead zones. Similarly, marsh grasses settle out sediment, heavy metals and chemical pollutants and neutralize them by depositing them in the earth.These traits combine to make Chesapeake Marshes one of the most diverse and abundant ecosystems in the world. 
NPS Why should we care about marshes?For most of history the vast majority of Chesapeake waterways would have been lined with wetlands, these conditions were directly responsible for the abundance that allowed for the first successful European settlement of the new world. The very same abundance that supported Indigenous groups for thousands of years and would eventually lead to the many rich water-based Chesapeake cultures and traditions, as well as Baltimore's industrialization where goods were canned and shipped over railroad to inland markets. It is not an exaggeration to say that most pre-industrial historic viewscapes are inaccurate without significant wetland coverage.Because they have evolved to thrive in flooded ecosystems, marsh grasses also have an unrivaled ability to soak up and store water in their biomass, with each acre being able to soak up 1 million gallons of water, which is slowly and safely released when water levels retreat. This means that wetlands significantly reduce erosion and damage from floodwaters and storm surges. This provides an invaluable service to cultural and historic resource managers charged with protecting sensitive structures that are often found at or near the water's edge.
By reducing sedimentation, improving fishery conditions and controlling erosion and floodwater marshes represent an immense monetary value to coastal property, the Port of Baltimore and the residents of the Chesapeake Bay at large.
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Last updated: October 3, 2024