Changing Climate Is
Impacting Rhode Island’s Fragile Ecosystems
By
Alex Burrows and Tanner Steeves in RIDEM’s Wild
Rhode Island
 |
| Photo by Will Collette |
The
Ninigret section of Charlestown is well known to Rhode Islanders and visitors
as one of the most beautiful natural heritage sites in the state.
The
forested trails, grassland, coastal pond and salt marshes host a wide variety
of wildlife and marine species which make it a unique and beloved natural
space.
Unfortunately,
the Ninigret salt marsh and salt marshes all along the East Coast are being
threatened and degraded. Increases in global temperature are causing sea levels
to rise at an accelerated rate, and as a result, Rhode Island’s fragile yet
essential habitats are disappearing.
A
loss of salt marsh habitat will have long term effects on Rhode Island’s
fisheries, wildlife, coasts and people.
Salt
marshes are unique coastal habitats that develop along sheltered coastlines
within intertidal zones and between terrestrial and aquatic habitat, and they
are vital to both humans and wildlife.
These unique ecosystems provide crucial habitat to multiple species of birds, fish, invertebrates, and many other organisms.
Vegetation
becomes established as sediment accumulates in inter-tidal areas. Over time,
roots from the vegetation become entangled and form a thick mat, which helps to
hold the marsh together and prevent erosion.
These
ecosystems are typically distinguished into two areas as low marsh and high
marsh habitat. Low marsh habitat is almost always inundated at high tide, while
high marsh habitat is less frequently flooded, usually by the highest tide.
This
results in differing levels of salinity, moisture content, and soil
composition.
These
factors determine what types of vegetation will grow in specific areas; grasses
are more common in low marsh areas while high marsh habitat tends to consist of
more low-growing shrubs.
The
vegetation within salt marshes provides critical nesting habitat for birds like
the salt marsh sparrow (Ammodramus caudacutus), seaside sparrow (Ammodramus
maritimus), and willet (Tringa semipalmata).
Salt
marshes are also beneficial to humans as they protect coastlines from erosion,
and filter sediment from the water as the tide ebbs and flows.
Sea
level rise, as a result of climate change, threatens the persistence of salt
marshes. Low and high marsh habitat become inundated by seawater, causing a
change in the composition of the marsh by increasing salinity and moisture and
decreasing oxygen in certain areas, and ultimately degrading the habitat.
As
the mean high tide line creeps further inland, salt marshes are unable to
migrate at a similar rate, resulting in significant habitat loss.
Projections
show that sea levels in the northeastern United States are expected to rise
several feet by 2100 (NOAA); even a small proportion of this estimate will have
grave consequences to Rhode Island salt marshes.
This
change will affect coastal communities by reducing salt marshes’ capability to
act as a buffer from storms, protect shorelines, and serve as a natural filter.
Nesting
habitat for birds that rely on these ecosystems would also be eliminated, and
the populations of many other species of flora and fauna would be reduced.
It
is important that we take steps to preserve these delicate ecosystems not only
for their aesthetic value, but for the crucial role they play in the well-being
of our communities and the longevity of wildlife populations.
RIDEM
and other conservation organizations are working proactively to enhance and
sustain these critical habitats.
At
Ninigret Pond, a large area of salt marsh owned by RIDEM is undergoing an
extensive restoration to adapt the salt marsh to higher water levels by the
Coastal Resources Management Council (CRMC) and Save The Bay.
A
technique called thin layer deposition was completed in early 2017, wherein
dredged material removed from the Charlestown breachway was spread across the
marsh surface to raise the elevation of the marsh by approximately one foot
across nearly 20 acres.
Vegetation
will naturally recolonize the site, and thousands of seedlings were planted to
help facilitate the revegetation process.
Small
channels known as runnels were also installed to improve tidal flushing and help
drain fresh water that had become impounded at upper sections of the high
marsh.
This
innovative project will improve the Ninigret salt marsh and help future
attempts at salt marsh adaptation as conservationists work to help these
ecosystems persist before they are permanently lost.