Wetlands ecology Self-taught education unit

[From the U.S. Government Printing Office, www.gpo.gov]

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@Wetlands Ecology

By Pam Mason

OBJECTIVES

The purpose of this unit is to familiarize yourself Wetlands can be vegetated or nonvegetated. The
with the fundamental aspects of wetlands ecology. This plants that vegetate wetlands are called hydrophytes
review will touch on the role of wetlands in the ecosys- meaning water loving. Hydrophytes are adapted to life in
tem, what makes a wetland, different wetland types and the water. Adaptations can be morphological, reproduc-
the plants and animals of the wetland. tive or physiological. Plants that have adapted to grow in
Following completion of the module, you will: saline waters are called halophytes meaning salt loving.
1) have a basic understanding of the role of wetlands in Some common terms can be used to describe tidal
the ecosystem, 2) be able to recognize wetlands, and 3) wetlands by their relative position in the landscape. The
define/describe hydrophyte, primary production, detritus, low marsh is the area of the lowest elevation, often vege-
secondary production, food web, zonation. tated by saltmarsh cordgrass or pickerelweed. The high
LECTURE NOTES marsh is generally above mean high water and is vege-
tated with saltmeadow hay, saltgrass, big cordgrass. The
Introduction marsh-upland ecotone, where the wetlands grade into
the uplands, is often indicated by the growth of shrubs
What is a wetland? A wetland is composed of three like the marsh elder, highwater bush and wax myrtle.
fundamental components; Water, plants and soil.
The water that makes wetlands wet is referred to as Ecosystem Functions
wetland hydrology. Wetland hydrology can come from Primaryproduction and the food web
many sources. The water may come from tides or nonti- Green plants use the sun's energy to convert inor-
dal sources such as rain, streams or groundwater. Tidal ganic (nonliving) minerals to organic (living) plant tissue.
waters can be salt or fresh. In most tidal systems there is This process is know as photosynthesis. As the first-
a gradient from saltwater to freshwater progressing up- level of production of organic material the process is
stream. In general nontidal wetlands are freshwater, al
though some are saltwater. This can occur where there is called primary production.
a high amount of dissolved minerals in the water and high Plant species common to wetlands have high levels
of primary production. Estimates of the primary produc-
evaporation rates increase the concentrations (Chapman,
1960). tion of tidal wetlands are as high as 4-6 tons per acre per
Wetland soils are hydric soils. When soils are inun- year. Wetlands productivity rivals or surpasses the most
dated with water, anaerobic (without air) conditions usu- -productive farmlands (Tiner, 1984).
ally result. Anaerobic conditions lead to chemical Animals that feed directly on plant material are
changes in the soils. Hydric soils are generally dark in called primary consumers. However, few animals eat
color. the vegetation and most of the plant material becomes de-

tritus'. Detritus is partially decomposed plant material. 2. High rates of primary productivity may lead to
Depending on the wetland system, some or most, of the high rates of nutrient uptake and subsequent burial
material is exported to the estuary. when the plants die.
Many types of microorganisms grow on the detri- 3. The nutrients used by the growing wetlands
tus. The tiny plants and animals which populate the de- plants are not available to support the development of
tritus increase the value of the detritus as food for algal blooms (Mitsch & Gosselink, 1986)..
estuarine organisms. The d .etritus is consumed by Fish and Wildlife Habitat
many animals, including crabs, fish and shellfish. The A great variety of birds, fish, mammals and inver-
consumers digest the microorganisms growing on the tebrates use .wetlands for foraging, shelter, nesting,
detritus. However, the detritus is only partially broken-
down and passes through mostly undigested. The.detri' spawning and nursery areas. Some species of plants
and animals can survive only in wetlands such as salt-
tus is repopulated with microorganisms and the process marsh cordgrass a .nd muskrats. However, many other
is repeated. species use wetlands for food or refuge but not as a pri-
The higher level consumers in the process are mary residence.
those that feed on the detrital consumers. Examples of
Many species of finfish, including most commer-
higher level consumers are shorebirds, finfish and mam- cial and game fishes use wetlands as habitat. Striped
mals including humans. bass, white perch and herrings ai@e just some of the fa-
Water Quality miliar fishes which-use wetlands. Crustaceans, like the
Wetlands occupy a strategic position in the land- blue crab and. shrimp also use wetlands. Many species
scape between uplands and the aquatic environment. of shellfish are found in wetlands or the adjacent shal-
Wetlands can intercept upland runoff and filter and trap low waters. Oysters, clams and mussels use wetlands
pollutants and sediments before they reach the water- as habitat.
way. Several wetlands attributes have the potential to Shoreline Erosion Control
affect the flow of chemicals and sediments.
Wetlands deter shoreline erosion by reducing wave
1. Wetlands vegetation slows water velocity, caus-
ing sediments and sorted chemicals to drop out of the energy and current velocity. Roots and,rhizomes of
water column on to the wetland. wetland plants stabilize the s .ubstrate, and the stems and
leaves slow the flow of waves and tidal currents. Al-
though lacking vegetation, the natural slope of nonvege-
Wetlands Program December 1993 tated wetlands provide a buffer to shoreline erosion.
College of William and Mary
School of Marine Science Wave and tidal curr.ent energy is dissipated as the water
Virginia Institute of Marine Science spreads out over the flats.
Gloucester Point, Virginia 23062 Flood Protection
Dr. Carl Hershner, Program Director Wetlands may slow and temporarily store flood wa-
Published by: VIMS Publication Center ters. The capacity for flood water storage is influenced
"A publication of the Virginia Department of Environmental by the tidal stage. Portions. of the wetlands already
Quality's Coastal Resources Management Program pursuant to flooded by tidal waters may be unable to assimilate ad-
National Oceanic and Atmospheric Administration Award ditional flood waters. This is particularly true of low
No. NA270ZO312-01. " marsh areas with daily tidal inundation. The absorption
"This paper isfunded in part by a grant1cooperative
agreementfrom the National Oceanic and of flood water by wetlands and the ability of vegetation
S Atmospheric Administration. The views expressed to slow flood waters desynchronizes peak flows mini-
herein are those of the author and do not necessarily mizing downstream flows.
reflect the views of NOAA or any sub-agencies.

Printed on recycled paper.
AQ
'41
" NW04"111-8

Wetland Types high marsh is a mixed community of saltgrass and salt-
Generally it is common to group wetlands into cate- meadow hay with saltbush along the upland edge. Oyster-
gories according to salinity regimes. Salinity influences catchers, egrets, herons, blue crabs, fiddler crabs and
the kinds of plants and animals present in the wetland. finfish are common inhabitants of the saline marsh.
Euhaline (Marine). Marine marshes have waters Brackish (Polyhaline and Mesohaline). The
with a salinity close or equal to seawater. The vast expan- seawater is gradually diluted by freshwater and the salin-
sive marshes behind the barrier islands on the eastern ity ranges from above and below 16 parts per thousand.
shore are saline marshes. Dominant vegetative species in- The marshes are found in the lower Chesapeake Bay and
clude saltmarsh cordgrass, saltmeadow hay, saltgrass and extending up the major tributaries and creek systems.
highwater bush. Zonation of the vegetation is simple and The vegetation is more diverse than the saline mars 'hes.
Bulrush, sea lavender and cattails are common in addition
easily observed. Tall form saltmarsh cordgrass grows at
lower elevations adjacent to the marsh creeks,@ short form to saltmarsh cordgrass, saltmeadow hay and sattgrass.
saltmarsh cordgrass occurs in the mid-marsh, and the Saltmarsh cordgrass grows adjacent to the creeks, salt-
grass and saltmeadow hay with sea lavender and black

'J i
EXTREME HIGH TIDE
N ......... . ...... ........ .. ....... ..........................................................
UPLAND
.MARSH.U LAND MEAN HIGH TIDE
BORDER P ER ...... ............................. ............................
IIIG I A 'I PANNE MEAN LOW TIDE
POOL .... ..... .......
LOWER HIGHMARS11 LOW MARS11 INTERTI
D L -------
FLAT AQUATIC BED

Eelgrass
Widgeon Grass
Smooth Cordgrass
Glassworts
Sea-Blites
Marsh Fleabane
Marsh Orach
Salt Hay Grass
Spike Grass
Perennial Salt Marsh Aster
Black Grass
Hightide Bush
Seaside Goldenrod
Bulrushes
Rose Mallow
Common Reed
Sea Myrtle
Grass-Leaved Goldenrod
Switchgrass
Marsh Pink
Slough Grass

Figure 1. Generalized disiribution of vegetation in a salt marsh. Note increased plant diversity along marsh-upland
border. (Tiner, 1985, 1987)

needlerush occupy the mid-marsh and the upland edge fresh community is much greater than other tidal wet-
is marked by highwater bush and marsh'elder. Animals lands. Fifty species per acre is typical. Just a few of
found in the brackish marsh include marsh snails, grass- the commorn plants are; arrow arum, pickerelweed, wild
hoppers, clapper rails and fiddler crabs. rice, rice cutgrass, cattails, and smartweeds. Zonation
Oligohaline. These wetlands form the gradient is less sharply defined, however a general profile may
from brackish to tidal freshwater. Located along the be described (Odum, 1984). Arrow arum and pickerel-
Bay, niajorSributaries and creeks, increased freshwater weed at the lower elevations adjacent the waterway,
input dilutes the seawater to around 3 parts per thou- smartweeds, wild rice, big cordgrass and rice cutgrass
sand. Saltmarsh cordgrass may still be found along the at higher elevations, cattails near the upland and wax
waters edge, but many other less saline tolerant species myrtle and red maple along the upland edge. A large
are also'found. Big cordgrass, sedges and three square - diversity of animals is a consequence of the great vari-
grow here. Zonation patterns become less pronounced ety of plants. Amphibians and reptiles are common, as
as salinity decreases. Saltmarsh cordgrass is still found are migrating waterfowl, muskrats, river otters, voles,
at the lower elevations, big cordgrass, cattails, bulrush raccoons and many other animals.
and marsh mallows may all occur at the higher eleva- Tidal Swamps. These wetlands are found at the
tions. upper end of tidal influence. The presen ce of trees dif-
Tidal Freshwater. The average salinity is 0.5 ppt, ferentiates tidal swamps from tidal marshes., In many
or lower, except during drought. These wetlands occur swamps, the tidal swamp grades almost imperceptibly
upstream of oligohaline marsh and downstream of non- into a nontidal swamp. Trees in tidal swamps generally
Odal wetlands. The vegetative diversity of the tidal grow on hummocks. Trees within tidal range are gener-

Figure 2. Food web.

TOP CARNIVORES

'Noma
microalgae

PS MARY
IN
CONSUMERS
RW
PRODUCERS
AM-0
- : <
bacterl 'k
and' e MLW
Protozoa
-zooplanklon-
SECONDARY
CONSUMERS V
DECOMPOSERS &
DETRITUS FEEDERS
TI- TERTIARY
CONSUMERS

SAND 9 MUDFLAT INFAUNA

ally smaller and show autumn colors earlier than trees Communities (Types are after the Virginia
above tidal influence. Tree species found in tidal swamps Wetlands Cuidelines)
include- gums, red maple, green ash and bald cypress.
Dragonflies and other insects are common. Amphibians Type 1. Saltmarsh cordgrass community.
and reptiles, including spring peepers, water snakes, bull- This community is dominated by Spartina alterni-
frogs and turtles, are found in tidal swamps. White-tailed flora. This species is a tall grass reaching 4-6 feet tall
deer, red fox and other upland animals wander into the near the waters edge. There are distinct growth habits of
swamps. Beavers, which were once gone from the Spartina according to height. There is a tall form, a short
Chesapeake Bay region, are once again inhabitants of form and some have proposed an intermediate height
tidal and nontidal swamps. form of the species exists. The tall form is found growing
adjacent to the marsh creeks and the short form grows fur-

AVERAGE ANNUAL
SALINITY MARSH TYPE

NON-TIDAL
FRESHWATER
0-0-0 0-0-0 (DURING
LOW
11DAL FLOW
LIMIT OF FRESHWATER CONDITIONS)
TIDAL INFLUENCE

* 0.5 Ppt - - - - - - - - - - - - - - - - -

OUGOHALINE
I E
* 5.0 ppt - - - - - - -- - - - - - - - - S
T
T MESOHALINE U
A
< 1&0 Ppt - - - - - - R
Y

V0, POLYHALINE
1A

< 30.0 ppt
-------------- ---- J

OCEAN

EUHALINE
(MARINE)

Figure 3. The relationshigbetween marsh type and average annual salinity (values are approximate only). Terminology
is based on Cowardin et al. (1979). (Odum et al, 1984)

ther from the creeks. It has been theorized that the tall with swirls. The vegetation is found growing from
form plants receive a "tidal subsidy" from the increased about mean high water to the limit of spring tides.
availability of tidal borne nutrients. Primary productivity is around 1-3 tons per acre.
Spartina grows from about mean sea level to mean However, tidal flushing of this community is limited to
high water which is approximately the-upper two thirds spring and storm tides so much of the vegetative mate-
of the tidal range. The location of the community rial remains in the marsh and is not available to the ma-
within the tidal zone results in daily flushing by the rine community.
tide. The seed heads of the plants provide food for birds
The primary productivity of Spartina is very high. and some birds nest in this community. Invertebrates
The average production is about 4 tons per acre but like the saltmarsh snail (Melampus) are important food
may be as. high as 10 tons per acre. Tidal action trans- for waterfowl, seaside sparrows and rice rats.
pofts the detritus making it readily available to the ma- The dense growth habit of the vegetation provides
nne community. an effective erosion deterrent, however, the position of
Tidal fluctuations allow aquatic animals access to the community at. the higher elevations affords little op-
the marsh. Adults of small fish species (killifish, ancho- portunity to guard against shoreline erosion. If the com-
vie's) and juveniles of many species (striped bass, spot, monly occurring saltmarsh cordgrass is absent from the
croaker) use the marsh for protection and a feeding lower elevations, this community will deter shoreline
area. Blue crabs and shrimp also forage and find ref- erosion. The saltmeadow community is often the older
uge in the Spartina. The marsh periwinkle, which part of the marsh with deep accumulations of marsh
clings to the'stems of the vegetation, and the ribbed peat. Flood waters fro -in high tides and upland runoff
marsh peat. The salt-
mussel are important as food for aquatic animals as may be absorbed by the deep
well as bird and small mammals. meadow acts as a trap, filtering the sediments, nutrients
The roots and rhizomes of the plant are used as and toxics carried by the flood waters.
food by waterfowl. Some birds use the vegetation as Type Ill. Black Needlerush Community.
nesting material including the clapper rail and willet. This community is dominated by black needlerush
Muskrats use the plants in the construction of lodges. (Juncus roemerianus). This plant usually grows in pure
Raccoons and other small mammals can use the
stands with saltmarsh cordgrass, saltmeadow hay and
Spartina community as a foraging area. saltgrass occurring at the edges. The'plants have hard
The Spartina community is an effective deterrent cylindrical stems tapering to a sharp tip. The'plants ap-
to shoreline erosion. The high growing densities, of the pear leafless,as the leaves form a sheath around the
vegetation reduce wave. energy. The,peat is very resis- stem. The species blooms from June to August. Jun-'
tant to wave energy due to the dense growth of roots cus grows from about mean high water to somewhat be-
and rhizomes. The baffling effect of the vegetation low spring tides. The community often grows in
slows the flow of tidal waters and upland runoff. As pannes, low areas of the marsh where waters accumu-
the water velocity is reduced, sediments are deposited late and evaporation increases salinity.
on the marsh. This.property makes the Spartina com- Black needlerush produces about 3-5 tons per year
munity effective as a trap for sediments from upland of vegetative material. Due to the rigid natureof the
runoff. species, plants decompose slow 'ly and the location of
Type 11. Saltmeadow co mmunity. the community in the high marsh limit's the amount of
This community is dominated by saltmeadow hay material flushed by the tide.
(Spartina patens) and saitgrass (Distichlis spicata).. It It does not appear that any animals feed on Juncus,
is common to find saltmarsh cordgrass, marsh elder, however the dense, stiff vegetation provides cover for
groundsel tree and other plants growing in this commu- some species. Clapper rails nest in the vegetation.
nity. Saltmeadow hay and saltgrass reach about 1-2 The dense system of roots and rhizomes is resistant
feet in height. Large expanses appear meadow-like to, erosion. The opportunity to provide shoreline ero-

sion protection occurs on some sandy shores and low on the stems and seeds. The meadow vole nests among
sand berms. The vegetation is an effective trap for sedi- the stems as does the marsh rice rat, often taking over the
ment, although not as effective as the densely matted salt- nest of a marsh wren.
meadow community. The absorbent substrate acts to As other species of marsh grass, the dense network
buffer coastal flooding. of roots and rhizomes binds the marsh substrate providing
Type IV. Saltbush Community. a deterrent to shoreline erosion. Growing at higher eleva-
This community is comprised.of groundsel tree or fions in the tidal zone the opportunity to provide shoreline
highwater bush (Baccharis halimifolia) and marsh elder erosion control is limited; however, it may be particularly
(Ivafrutescens). Saltmeadow hay, and saltgrass are often important.for low salinity wetlands where the lower inter-
found growing underneath the bushes. Groundsel tree tidal zone is occupied by species that die back each fall.
reaches about 15 feet in height, the leaves are alternately Big cordgrass often is associated with the deep marsh
arranged on the branches, and it has conspicuous yellow- peat common at higher elevations in the older portion of
white flowers which bloom September through October. the marsh. The deep peat increases the capacity for hold-
Marsh elder is 3 to 10 feet high, the leaves are opposite ing flood waters. Where the community is found growing
on the branches, and the flowers are small greenish-white adjacent to the uplands, flood buffering may allow for the
appearing from August to October. The bushes grow at settling and trapping of upland sediment, nutrients and
the upper limit of the marsh (the marsh-upland ecotone). toxics. The plants are also effective at trapping larger flot-
Primary productivity is low, about 2 tons per year, sam.
and little vegetative material reaches the marine environ- Type V1. Cattail Community.
ment. The shrubs provide diversity to the grasses and There are two common species of cattails in this com-
reeds common to the marsh. Small birds, like the marsh munity, the narrowleaf cattail (Typha angustifolia) and
wren, nest among the branches. the broadleaf cattail (Typha latifolia). The plants may be
The growth habit of the shrubs does not serve well as found growing with other brackish and freshwater plants
a sediment trap, but does effectively trap larger flotsam. including; sedges, bulrushes, smartweeds, arrow arum
Often found growing on sand berms in front of small and pickerelweed. Both species grow to heights of 4 to 6
marshes, the bushes do provide some erosion protection. feet, have long strap-like leaves with slightly rounded tips
and have the characteristic fruiting head. Both the male
Type V. Big Cordgrass Community. and female flowers occur together on one flowering
Big cordgrass (Spartina cynosuroides) usually
grows in monotypic stands. The grass is- very tall, 6 to 12 spike. In the broadleaf cattail the upper (male) spi@e and
feet, and has a distinct feathery fruiting head in the fall. the lower (female) spike are touching, in the narrowleaf
The plants are very sturdy and standing dead plants often there is a space between the spikes.
persist through the winter. Big cordgrass grows from just Cattails prefer very wet soils and sometimes grow in
above mean high water up to thq upland margin. The standing water. They prefer low salinity waters. Look
plant is most common in brackish and lower salinity for cattails along the upland margin where groundwater
marshes. seepage keeps the soils wet and the salinity low. The
Levels of primary productivity range from 3 to 6 tons vegetative material produced by cattails,, about 2 to 4 tons
per acre in this community'. Primary productivity rates per acre, is not readily accessible to the marine environ-
are similar to saltmarsh cordgrass and higher than most ment.
other species growing above mean high water. However, Some species of birds use cattails as habitat. Marsh
the position of the community at the higher elevations re- wrens and rice rats build nests attached to the plants. The
plant roots are eaten by muskrats.
sults in the transport of the vegetative material being lim-
ited to high spring, wind and storm tides. The cattail community offers little erosion protection
- Various animals use big cordgrass for cover, food or due to the preferred location adjacent to the uplands and
building materials. Muskrats use the material for build- the shallow root system of the plants. However, both of
ing lodges. Geese eat the rhizomes and other birds feed

these characteristics make the community effective as a leaves are shed in the fall, individual stems and seed
sediment trap, particularly from upland runoff. -heads often persist through the winter.
Phragmites usually grows above mean high tide,
Type V11. Arrow Arum - Pickerel Weed
Community. . particularly in brackish areas. The plants will also-in-
The dominant plants of this community are arrow vade the drier areas of disturbed sites. Primary produc-
arum (Peltandra virginica) and pickerelweed (Ponted- tivity rates range from 4 to 6 tons per acre, but the
eria cordata). The plants may grow in association with relatively high elevation occupied by the community re-
sedges, smartweeds, cattails and pond lily. Both spe- sults in little transport of vegetated material.
cies have dark green fleshy leaves and grow in clumps There is little evidence of wildlife use of this com-
about 3 feet high. Arrow arum has leaves shaped like munity. The vegetation may provide cover for some
birds and small mammals. Where Phragmites invades
arrowheads, with a prominent midvein. Arrow arum
blooms from May to July, but the flowers. are concealed disturbed sites, there may be a detrimental effect on
wildlife use due to the decrease of vegetative species
in a sheath called a spathe. Pickerelweed has heart-
shaped leaves with parallel v .eins.. The plants bloom which are important to wildlife.
from May to October and the showy purple flowers are The sturdy nature of the grass makes for a good
borne on flowering spikes up to 4 inches long. shoreline erosion deterrent. Due to the ability to invade
Arrow arum and pickerelweed can be found in non- dry, disturbed areas, this species is often found growing
on dredge material acting to stabilize the material.
tidal freshwater wetlands as well as low salinity and
tidal freshwater wetlands. In tidal waters, the commu- Type IX. Yellow Pond Lily Community.
nity grows from'about mean sea level to about mean Yellow pond lily (Nuphar luteum) grows in fresh-
high tide in low salinity and freshwater marshes. This water and may be associated with arrow arum and pick-
is the same landscape position occupied by saltmarsh erelweed. The large saucer shaped leaves float on the
cordgrass in higher saline waters. water surface at high tide. The plants flower from June
About 2 to 4 tons per acre of vegetative material is to September and have a large yellow flower. The
produced in this community. The organic material is leaves and flowers of the 2 to 4 foot tall plants are emer-
readily available to the marine system. Unlike many gent at low tide,
other common welland plants such as the marsh The floating leaves of one plant occupy several
grasses, these species decompose quickly and com- square feet so plant densities are generally low. Pri-
pletely in the fall. mary productivity approaches one ion per acre. Vegeta-
The soft, unconsolidated intertidal muds are suscep- tive material enters the marine environment, but the
tible to erosion. Without a dense network of roots and contribution is small compared to other marsh species.
rhizomes, the plants can serve to stabilize the shoreline Yellow pond lily is found in river stretches associ-
only during the year when the leaves can act to baffle ated with spawning striped bass, white perch and river
wave energy. Due to the complete -die back of -the vege- herring. The plants provide attachment sites for algae
tation each fall there is -no standing dead material to pro- and aquatic animals. Wading herons, egrets and other
tect the shoreline from erosion in the winter. The large waterbirds forage on the small fish and invertebrates
leaves of the vegetation can slow tidal waters and among the floating leaves. Finfish also forage in the
waves to allow some sediment deposition. yellow pond lily. A resident of freshwater marshes, the
Type VI I[I. Reed Grass Community. eastern painted turtle may be found feeding here as
This community is dominated by reed grass well.
(Phragmites communis). This grass often grows in While lacking stiff stems and leaves, the large
pure stands, but may be found growing with saltbush leaves do provide some baffling of wave energy. By re-
ducing wave action, the community provides some
and switchgrass. Phragmites is a tall stiff grass reach-
ing 6 to 10 fe .et in height. The plants bloom in July and shoreline protection and allows fo Ir the settling of some
August and have a large, feathery seed head. After the water borne sediments.

Type X. Saltwort Community. arrow arum, pickerelweed, smartweeds, wild rice and rice
There are three species of vegetation commonly cutgrass are among the species which may occur in a
called saltwort found in Virginia. The three species are: freshwater mixed community wetland. Because this com-
Salicornia virginica, Salicornia biglovii and Salicornia munity encompasses many vegetative species, each with
europa. Saltworts are leafless succulents. with thick a preferred elevation, the community may be found grow-
green, edible stems. S. europa and S. biglovii are dif- ing from the subtidal zone to the upper limits of wetlands.
fusely branched, fleshy annuals. Salicorma virginica is a Primary productivity of this community depends
perennial with woody stems and typically grows in dense greatly on the species present. An average value is 3 to 5
mats, Saltworts grow in saline and higher salinity brack- tons per acre. The vegetative material produced by interti-
ish marshes above mean high tide in pannes and sparsely dal species is readily available to the marine environment.
vegetated areas. The high diversity of the freshwater mixed wetland
Primary productivity is less than 1/2 ton per acre. provides foraging areas, nursery areas and nesting sites
There is some evidence that some ducks eat the stems. for a myriad of wildlife species. These wetlands occur
Wading birds and other marsh birds may forage where along river and creek stretches where striped bass, shad
-small fish and invertebrates get trapped by the receding and river herring spawn. The juvenile fish can find shel-
tide in Salicorma pannes. ter among the intertidal vegetation. Wildrice, arrow arum
The diminutive habit of the leafless plants, the shal- and smartweeds are consumed by native and migratory
low root system and the preferred location of this commu- waterfowl, sora rails, redwinged blackbirds and upland
nity offers little erosion- protection, flood buffering or birds. Insects, amphibians and reptiles are more common
sediment trapping capabilities. than in the brackish and saline marshes.
Type X1. Freshwater Mixed Community. The shoreline erosion deterrent of this community is
This community type applies to freshwater wetlands the same as the arrow arum and pickerelweed community
with a heterogeneous mix of vegetation and no single spe- 'because these species grow at the lower elevations adja-
cies covers more than 50 percent of the site. Bulrushes, cent to the waterways. However, due to-the presence of
grasses, sedges, rushes and a peaty substrate at the higher

Figure 4. Marsh to uplands transition in
a typicalfreshwater marsh.

BIDENS (seasonal)

N N-TIVAL
DEPRESSION

GREENBRIER BUTTON BUSH SEDGES SMARTWEED
RED MAPLE TOUCH-ME-NOT MARSH MALLOW ARROW ARUM
POISON IVY ROYALFER TEARTHUMA PICKEREL WEED
SWEET PEPPERBUSH- CATTAIL 810 CORDGRASS ARROWHEAD
SWAMPROSE- IRONWEED .11- 1 - YELLOW POND LILY
SOUARESTEM SPIKEFIUS SEDGES
MARSH FERN WILD RICE

elevations, the freshwater mixed community is effec- As this community is most often bordered by salt-
tive as a sediment trap and assimilator of flood waters marsh cordgrass, the community provides effective
(Figure 4). shoreline erosion control. Likewise, the attributes of
Type X11. Brackish Water Mixed Community. the commonly, occurring saltmeadow community spe-
This community is comprised of various brackish cies, saltmeadow hay and saltgrass, provide effective
wetlands species. No single species cover more than sediment trapping and flood buffering capabilities
50 percent of the site. This diverse vegetative commu-' (Figure 5).
nity may include saltmarsh cordgrass, saltmeadow hay, Type X111. Intertidal Beach Community.
saltgrass, saltbushes, threesquares, big coidgrass, com- The intertidal beach is nonvegetated. The domi-
mon reed and cattails: This community may extend nant animal species are burrowing invertebrates. Ani-
from the lower limit of saltmarsh cordgrass, about mals that live in the substrate are called infauna.
mean sea level, to the upland margin. Wandering species and nonmobile species attached to
Primary productivity of the brackish mixed com- hard substrates are called epifauna. There is some vafi-
munity ranges from 3 to 5 tons per acre. The detritus of ability between species commonly found on bay
the intertidal species is available to the marine food beaches and those most often associated with ocean
web. beaches. On the ocean beach, mole crabs, donax clams
As is the case with the freshwater mixed wetlands, and haustorid amphipods are common. Amphipods are
a wide diversity of vegetation provides a variety of also common on bay beaches as are oligochaete worms
wildlife food and shelter. Many species of waterfowl and sand fleas. These animals occur in large numbers;
feed on the seed heads. Shorebirds and wading birds in the summer there may be as many as 5000 individu-
forage for plentiful invertebrates. Fiddler crabs and als per square meter-
marsh crabs are common. Raccoons forage for crabs Lacking the macrophytes, large plants, of the vege-
and shellfish. Small mammals such as the meadow tated wetlands, primary production is relatively low.
vole and rice rat, feed on the vegetation and inverte- The primary producers of the nonvegetated wetlands
brates. Foxes are attracted by the small mammals, are microscopic plants including algae and phytoplank-
marsh birds and invertebrates.

Figure 5. Marsh to uplands transition in
a typical saltwater marsh.

---------- TRANSITION ZONE -----------

SALTMARSH BULRUSH
ALOM FRIF"ATER STREAMETS

A...

PINE GROUNDSEL TRE MARSH ELDE BLACK NEEDLERUSH
GREENBRIER SEA OXEYE RA
SALTMEADOW HA SPARTINA ALTERNIFLORA
RED CEDAR FOXTAIL GRASS SALTMEAD HAY Short form
WAX MYRTLE GREENBRIER SALT GRASS Tall form
GOLDENROD

ton. The production of animals, or secondary production, population densities are generally higher than sand or
is very high. mud flats and range from 5300 to 8300 individuals per
The large numbers of invertebrates are important square meter.
food for shorebirds. At high tide, finfish and blue crabs Primary production is similar to sand flats. How-
also forage for food. The areas above high tide are used ever, the smaller particle size and high organic matter con-
as nesting sites for terns, plovers and skimmers. tent, means greater microbial activity. Bacteria and
The low slope of the beach makes it a natural wave fungi, fundamental to the breakdown of detritus, are
dissipator. The dissipation of wave energy reduces the found in higher numbers in sediments containing small
potential for shoreline erosion. The beach interacts with grain size particles. Nutrient cycling activity is greater
dunes, offshore bars and adjacent shoreline in the distribu- than on the sand flat.
tion of sand. Shorebirds and wading birds feed on the invertebrate
Type XIV. Sand Flat Community. populations of the sand/mud flat. Waterfowl are attracted
Sand flats are populated by various surface dwelling by the mollusks. Blue crabs and fish use the area for for-
and burrowing animals. Sandworms, bloodworms, am- aging and shelter. This community often borders a vege-
phipods and clams are all found on the sand flat. Animal tated marsh which may increase the role of both
densities range from 300 to 3000 individuals per square 'communities as wildlife habitat. The marsh provides
meter. habitat variety and organic material to support nutrient cy-
Most of the animals complete their life cycle in one cling and food webs.
or two years. High rates of production and predation re- Shoreline erosion control is similar to sand flats.
sults in a rapid turnover of individuals. High predation Type XVI. Mud Flat Community.
acts as a control on the size of the animals, in general indi- Mud flat animal populations are dominated by
viduals are small. spionid- worms, mud snails, razor clams and bloodworms.
Primary productivity by microscopic plants ranges These animals are mostly surface dwelling or shallow bur-
from 100 to 200 grams per square meter. Primary con- rowers. The instable, anoxic mud limits the presence of
sumers graze on the small plants incorporating the vegeta- deep burrowers and deters species other than surface detri-
tive material into the food web. This community has a tal feeders. Animal -populations are highly variable. Gen-
reduced role in nutrient cycling due to the low percentage erally lower than sand/mud flats but higher than sand
of organics and the large particle size of the sand. flats, densities range from 50 to 5000 animals per square
. Sand flats are used as foraging areas, by shorebirds, meter.*
finfish and blue crabs. Juvenile blue crabs and finfish Of the nonvegetated wetlands, mud flats probably
seek shelter in the shallow waters where larger aquatic have the highest primary productivity. Mud flats interact
animals cannot go. Some sand flats support high shellfish with adjacent vegetated areas in nutrient cycling. The
populations. marshes provide organic material to the animal popula-
Like the intertidal beach, the low slope of this co in- tions of the mud flats which breakdown and transform the
munity acts as a natural dissipator of wave energy reduc- organic material.
ing the potential for shoreline erosion. Foraging wildlife are attracted by the invertebrate
Type XV. Sand/Mud Mixed Flat Community. populations. Waterfowl, wading birds, finfish and blue
crabs all feed on the mud flats.
Hard clams, soft clams, mud snails, parchment
worms and polychaetes are commonly associated with in- Mud flats occur frequently in quiescent areas and
tertidal flats composed of sand and mud. The animals-are have a limited opportunity to control shoreline erosion. -
surface dwellers, burrowers and some build permanent However, the gradual slope of the mud flat acts like the
tubes. Variability in particle size allows some overlap of other nonvegetated wetlands in the dissipation of wave en-
species common to sand flats and mud flats. As a result, ergy-

NOAA COAST
ly

12
862 P

Type XVII..Intertidal Oyster Reef Community. The nooks and crannies of the reef offer niches for
Oysters are the dominant- animal, but there is great manyaquatic animals. Small finfish find shelter among
diversity in the attached and associated organisms. the shells, larger fish forage on the reef. Blue crabs
Hard clams, mud crabs, sand w'orms, barnacles and feed on the reefs extensively. Oystercatchers and other
sponges are.associated with oyster reefs. When oyster birds also forage on the reefs.
reefs are managed by man, the oysters are most com- The rigid structure of the permanently attached
mon. In a natural state, fouling organisms are d 'omi- shells are resistant to erosion and may dissipate wave
nant. Populations are very variable, but are generally energy.
greater than flat communities.

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