What is a Salt Marsh?
A salt marsh, also known as a tidal marsh, is a coastal wetland ecosystem. Salt marshes include mudflats, estuaries, coastal plains and other intertidal zones that do not receive significant wave activity.
Salt marshes are inhabited by plants and animals that are able to tolerate salty or brackish water. These specialized species cannot survive in other types of environments. Pollution, habitat loss through development, and disturbances such as discharge of waste water that alter the salt content can make the ecosystem uninhabitable to these species, and many species that make their homes in salt marshes are now endangered.
Some Endangered Species of Salt Marshes
- Belding's Savannah Sparrow (Passerculus sandwichensis beldingi)- Native to southern California salt marshes between Santa Barbara and Baja California, this small ground-dwelling sparrow was first added to the endangered species list in 1974, when populations plummeted because of habitat degradation, fragmentation, or loss due to development. Current threats to Belding's Savannah Sparrow include human trespassing and encroachment, pets in the salt marshes, and continued habitat loss.
- Salt Marsh Harvest Mouse (Reithrodontomys raviventris)- The habitat of this tiny mouse is limited to the South San Francisco Bay in California. The Salt Marsh Harvest Mouse is able to eat food and drink water with quite a high salt content, a rare ability among land mammals. These mice require dense plant growth for shelter. The salt marshes where they live have three vegetation zones: the lowest is dominated by cordgrass, the middle by pickleweed, and the highest contains various types of salt-tolerant plants. The mice require all three zones so that they can seek shelter when the tide rises. They are endangered because of extensive habitat loss and degradation. Modification of habitat includes infilling, covering or converting the upper vegetation zone to salt ponds, pumping groundwater, and discharging fresh water from sewage treatment plants into the bay, thereby decreasing the salinity and changing the plants that grow there.
- California Clapper Rail (Rallus longirostris obsoletus)- Once abundant in the salt marshes all along the west coast of North America, the populations of California Clapper Rails were drastically reduced by hunting in the late 1800s. Hunting the Clapper Rail was prohibited beginning in 1915, but populations were unable to recover due to increasing habitat loss, and the species was listed as endangered in 1970. Fragmented habitat in the salt marshes facilitates access by predators such as feral cats and red foxes, and puts the birds at greater risk. Efforts are being made to control predators, but restoration of salt marsh habitats is the only way to effectively increase Clapper Rail populations.
- Maritime Ringlet Butterfly (Coenonympha nipisiquit McDunnough)- The range of the Maritime Ringlet Butterfly is limited to a 2 square km area in the salt marshes of Chaleur Bay, New Brunswick, on Canada's east coast. The food source for the caterpillar is Salt Meadow Cord Grass, and the adult butterflies eat nectar from Sea Lavender flowers. Therefore, both of these plants are required for the butterfly to survive. The habitat for the Maritime Ringlet Butterfly is in close proximity to urban areas, and it threatened due to infill of buffer zones and runoff containing pesticides, herbicides, and other chemical pollutants.
Habitat restoration and efforts to mitigate habitat loss are taking place in some areas where endangered species of salt marshes make their homes, but the long-term survival of these species is uncertain.
U.S. Fish and Wildlife Service www.fws.gov
Elements Online Environmental Magazine www.elements.nb.ca