Download Gulf of Maine Salt Marshes - NH Division of Forests and Lands

NATURAL COMMUNITIES OF NEW HAMPSHIRE
Gulf of Maine Salt Marshes
Salt marshes are naturally occurring grasslands
found within estuarine intertidal zones along the
coast. Together with the estuaries they occur in,
they are among the most biologically productive
systems on earth and support a vast array of
plants and animals, including many species of
migratory birds.
Although a wide variety of habitats occur within
salt marshes, two major types are the low salt
marsh and the high salt marsh. The low salt
marsh is flooded and exposed by the tide twice a
day. The high salt marsh is at or beyond the
reach of most tides but within the reach of
spring and storm tides.
High salt marshes are richer in plant species
than low salt marshes. Relatively few plant
species can tolerate the more stressful
environment created by the daily ebb and flow
of the tide in the low salt marsh. High salt
marsh accounts for more than 90% of the total
salt marsh habitat.
The boundary between the high and low salt
marsh is often marked by an obvious shift from
salt meadow cord-grass that dominates the high
marsh, to a much taller species, smooth cordgrass that dominates the low marsh ("low" refers
to the height of the land, not of the vegetation).
A variety of microhabitats within salt marshes,
such as tidal creeks and low, isolated areas
called pannes, harbor numerous plants
particular to the conditions, and provide food
and shelter to a great abundance and variety of
animal life. Bird species that are rare or unusual
that feed or nest in New Hampshire salt marshes
include the American bittern, seaside sparrow,
and osprey.
Characteristic and rare* plant species:
Where Are They Found?
High Salt Marsh
large salt marsh aster (Symphyotrichum tenuifolium)*
marsh elder (Iva frutescens ssp. oraria)*
New York aster (Symphyotrichum novi-belgii)
prolific knotweed (Polygonum prolificum)*
salt marsh rush (Juncus gerardii)
salt meadow cord-grass (Spartina patens)
seaside gerardia (Agalinis maritima)*
seaside goldenrod (Solidago sempervirens)
smooth cord-grass, short form (Spartina alterniflora)
spike-grass (Distichlis spicata)
sweet grass (Hierochloe odorata)
Salt marshes are found along the coast where
there is shelter from high-energy ocean wave
action, such as in the Great Bay Estuary, the
Blackwater-Hampton River Estuary, and the
Squamscott River Estuary. They are New
England's most abundant natural grasslands.
Low Salt Marsh
common glasswort (Salicornia europaea)
halberd-leaved orache (Atriplex hastata)
small spike-rush (Eleocharis parvula)*
smooth orache (Atriplex glabriuscula)
smooth cord-grass (Spartina alterniflora)
NATURAL COMMUNITIES OF NEW HAMPSHIRE
Related
Natural
Communities:
Salt marshes include pannes or pools that form in depressions more frequently inundated by
surface water than other areas of the marsh. These unique habitats within the salt marsh support
a variety of plant and animal species that differ from those found in the salt marsh itself. Other
closely associated natural communities within the intertidal zone include brackish marsh,
brackish tidal riverbank marshes, saline brackish intertidal flats, coastal shoreline strands/swales
and intertidal rocky shores.
Conservation
status:
Salt marshes are quite uncommon in New Hampshire. More than 1,200 acres, or 20% of the
original habitat, has been altered by human activities, especially those causing changes to tidal
flow. However, over 800 of these acres have since been restored1.
Conservation Considerations:
Healthy salt marshes and the estuaries in which they occur provide many ecological, aesthetic, and practical
values, including protection from storm flooding and erosion, and critical nursery areas for many fish species.
Salt marshes can be readily damaged by changes to either tidal or freshwater flow, and by increases in the amount
of nutrients or pollutants entering the wetland. Ditching, draining, or filling, as well as road, sewage, and
agricultural runoff from bordering lands, can all cause damaging changes. These activities can also lead to the
establishment of invasive non-native plants, which are another major threat to salt marshes.
In addition to their direct impacts, human activities can fragment the habitat and create cumulative negative
effects. Historically, salt marshes were extensively ditched in an attempt to control mosquitos and to increase
production of salt meadow cord grass for hay. More recently, unprecedented growth and development in the
coastal region of New Hampshire have increased the pressures on, and represent the primary threat to, salt
marshes and the many species and related natural community types found there. Intensive efforts to restore and
protect these habitats have been the result of a growing recognition of their values.
1
Soil Conservation Service. 1994. Evaluation of Restorable Salt Marshes in New Hampshire. Durham, NH.
These fact sheets were prepared by the NH Natural Heritage Bureau, a part of the Division of Forests & Lands in the
Department of Resources and Economic Development. NH Natural Heritage is a member of NatureServe, which
represents an international network of Heritage programs.
Detail from “Bufflehead at Bellamy River” by I.V. Seaboyer, © 1995.
For more information, please visit our web page at
www.nh.gov/dred/divisions/forestandlands/bureaus/naturalheritage or call (603) 271-2215.
NH Natural Heritage Bureau
PO Box 1856
Concord, NH 03302-1856
Funded by the Conservation License Plate Trust Fund (the "Mooseplate").
Mooseplate funds received by NH Natural Heritage are vital to developing information that leads
to the protection of native plant species and natural communities.