be the cause of widespread loss of pioneer marshes in
southeast England. The impact of storms along the coast
of the Gulf of Mexico has been identified as one of the
main reasons for the increased rate of wetland loss in the
United States in the period 2004-2009 when compared
with the previous five years (Dahl and Stedman, 2013).
The loss of salt marshes is particularly concerning as they
provide natural coastal protection and other valuable ecosystems services.
Bibliography
Dahl, T. E., and Stedman, S. M., 2013. Status and Trends of Wetlands in the Coastal Watersheds of the Conterminous United
States 2004 to 2009. U.S. Department of the Interior, Fish and
Wildlife Service and National Oceanic and Atmospheric Administration, National Marine Fisheries Service, 46 p.
Doody, J. P., 2012. Coastal squeeze and managed realignment in
southeast England, does it tell us anything about the future?
Ocean
&
Coastal
Management,
doi:10.1016/j.
ocecoaman.2012.05.008.
French, F. W., 1997. Coastal and Estuarine Management. London:
Routledge.
Hughes, R. G., and Paramor, O. A. L., 2004. On the loss of
saltmarshes in south-east England and methods for their restoration. Journal of Applied Ecology, 41, 440–448.
Pennings, S. C., and Calloway, R. M., 1992. Salt marsh plant zonation: the relative importance of competition and physical factors.
Ecology, 73, 681–690.
Pontee, N., 2013. Defining coastal squeeze: a discussion. Ocean &
Coastal Management, 84, 204–207.
COASTAL WETLANDS
Jorge R. Rey
Florida Medical Entomology Laboratory, University of
Florida – IFAS, Vero Beach, FL, USA
Definition
Coastal wetlands are habitats in close proximity to oceanic
or estuarine waters that are directly influenced by tides and
are covered permanently or periodically with salt or brackish water. In the broad sense, they include submerged
seagrass communities, tidal flats, and emerged salt
marshes and mangrove forests.
Coastal wetlands
Tidal flats are ecotonal areas between land and sea and can
extend from the subtidal through the intertidal and into
the supratidal zones. Although they often appear barren,
they can be highly productive and support large animal
populations. They occur throughout the world in areas
with significant fine-grained sediment deposition.
Seagrasses are submerged flowering plants occurring in
protected shallow estuaries generally with soft sediments.
They can form extensive beds that are important habitat
for a large number of animal species and play an important
ecological role in the nearshore estuarine environment.
See Tidal Flat for more details. Below we consider emergent salt marshes and mangroves.
We distinguish between coastal wetlands (situated
at or near the coast with direct influence of seawater
salinity) and tidal wetlands which can include freshwater
areas a considerable distance from the ocean but whose
hydrology is still influenced by tidal phenomena
that can propagate substantial distances upland (Rey
et al., 2012a). More or less distinct vegetation zones dictated principally by tidal inundation are common in
coastal wetlands, but vegetation mosaics and mixes are
also widespread, and sharp transitions often occur in
response to slight environmental gradients (Marani
et al., 2013).
The structure and function of coastal wetlands are
determined by many interconnected processes and feedback loops that operate at varying temporal and spatial
scales (Berger et al., 2008). Top-down constraints such
as landform and climate interact with bottom-up effects
such as local competition and individual plant photosynthesis to affect the structure and function of a given
wetland. Twilley and Rivera-Monroy (2005) divided these
processes into three types: regulators (non-resource
factors such as salinity, climate, etc.), resources (factors
used by organisms for growth such as nutrients, sunlight,
and space), and hydroperiod (the duration, frequency,
and depth of flooding).
The hydrological pattern of coastal wetlands is the dominant factor affecting their structure and function (Mitsch
and Gosselink, 2007). Hydrology affects many biotic and
abiotic processes which in turn may modify hydrology.
Examples of these include primary and secondary productivity, soil and water chemistry including anaerobiosis,
nutrient cycling, salinity, biological diversity, carbon
cycling, sedimentation dynamics, and microbial metabolism. In addition to climate and basin morphology, tidal
flooding and flow through tidal creeks and channels
(Perillo, 2009) are often the most important components
of coastal wetland hydrological dynamics. Other important
factors include subsurface composition, precipitation, surface flows, ground water flows, and evapotranspiration.
Sedimentation dynamics, which includes production,
transport, and sediment storage and is heavily influenced
by hydrology, also plays a critical role in wetland function
and maintenance (D’Alpaos et al., 2012).
The modification and transport of chemicals through
coastal wetland ecosystems (biogeochemical cycling)
result from a complex matrix of chemical, physical, and
biological processes, again, with numerous feedback
mechanisms, and give rise to many of the well-known
wetland functions such as carbon sequestration/export,
nutrient exports, and many others. Biogeochemical
cycling interacts with marsh hydrology and geomorphology to determine physical and biological conditions
within a given wetland. Major chemical cycles in coastal
wetlands include those of nitrogen, sulfur, iron, manganese, carbon, and phosphorous.
160
COASTAL WETLANDS
southeast England. The impact of storms along the coast
of the Gulf of Mexico has been identified as one of the
main reasons for the increased rate of wetland loss in the
United States in the period 2004-2009 when compared
with the previous five years (Dahl and Stedman, 2013).
The loss of salt marshes is particularly concerning as they
provide natural coastal protection and other valuable ecosystems services.
Bibliography
Dahl, T. E., and Stedman, S. M., 2013. Status and Trends of Wetlands in the Coastal Watersheds of the Conterminous United
States 2004 to 2009. U.S. Department of the Interior, Fish and
Wildlife Service and National Oceanic and Atmospheric Administration, National Marine Fisheries Service, 46 p.
Doody, J. P., 2012. Coastal squeeze and managed realignment in
southeast England, does it tell us anything about the future?
Ocean
&
Coastal
Management,
doi:10.1016/j.
ocecoaman.2012.05.008.
French, F. W., 1997. Coastal and Estuarine Management. London:
Routledge.
Hughes, R. G., and Paramor, O. A. L., 2004. On the loss of
saltmarshes in south-east England and methods for their restoration. Journal of Applied Ecology, 41, 440–448.
Pennings, S. C., and Calloway, R. M., 1992. Salt marsh plant zonation: the relative importance of competition and physical factors.
Ecology, 73, 681–690.
Pontee, N., 2013. Defining coastal squeeze: a discussion. Ocean &
Coastal Management, 84, 204–207.
COASTAL WETLANDS
Jorge R. Rey
Florida Medical Entomology Laboratory, University of
Florida – IFAS, Vero Beach, FL, USA
Definition
Coastal wetlands are habitats in close proximity to oceanic
or estuarine waters that are directly influenced by tides and
are covered permanently or periodically with salt or brackish water. In the broad sense, they include submerged
seagrass communities, tidal flats, and emerged salt
marshes and mangrove forests.
Coastal wetlands
Tidal flats are ecotonal areas between land and sea and can
extend from the subtidal through the intertidal and into
the supratidal zones. Although they often appear barren,
they can be highly productive and support large animal
populations. They occur throughout the world in areas
with significant fine-grained sediment deposition.
Seagrasses are submerged flowering plants occurring in
protected shallow estuaries generally with soft sediments.
They can form extensive beds that are important habitat
for a large number of animal species and play an important
ecological role in the nearshore estuarine environment.
See Tidal Flat for more details. Below we consider emergent salt marshes and mangroves.
We distinguish between coastal wetlands (situated
at or near the coast with direct influence of seawater
salinity) and tidal wetlands which can include freshwater
areas a considerable distance from the ocean but whose
hydrology is still influenced by tidal phenomena
that can propagate substantial distances upland (Rey
et al., 2012a). More or less distinct vegetation zones dictated principally by tidal inundation are common in
coastal wetlands, but vegetation mosaics and mixes are
also widespread, and sharp transitions often occur in
response to slight environmental gradients (Marani
et al., 2013).
The structure and function of coastal wetlands are
determined by many interconnected processes and feedback loops that operate at varying temporal and spatial
scales (Berger et al., 2008). Top-down constraints such
as landform and climate interact with bottom-up effects
such as local competition and individual plant photosynthesis to affect the structure and function of a given
wetland. Twilley and Rivera-Monroy (2005) divided these
processes into three types: regulators (non-resource
factors such as salinity, climate, etc.), resources (factors
used by organisms for growth such as nutrients, sunlight,
and space), and hydroperiod (the duration, frequency,
and depth of flooding).
The hydrological pattern of coastal wetlands is the dominant factor affecting their structure and function (Mitsch
and Gosselink, 2007). Hydrology affects many biotic and
abiotic processes which in turn may modify hydrology.
Examples of these include primary and secondary productivity, soil and water chemistry including anaerobiosis,
nutrient cycling, salinity, biological diversity, carbon
cycling, sedimentation dynamics, and microbial metabolism. In addition to climate and basin morphology, tidal
flooding and flow through tidal creeks and channels
(Perillo, 2009) are often the most important components
of coastal wetland hydrological dynamics. Other important
factors include subsurface composition, precipitation, surface flows, ground water flows, and evapotranspiration.
Sedimentation dynamics, which includes production,
transport, and sediment storage and is heavily influenced
by hydrology, also plays a critical role in wetland function
and maintenance (D’Alpaos et al., 2012).
The modification and transport of chemicals through
coastal wetland ecosystems (biogeochemical cycling)
result from a complex matrix of chemical, physical, and
biological processes, again, with numerous feedback
mechanisms, and give rise to many of the well-known
wetland functions such as carbon sequestration/export,
nutrient exports, and many others. Biogeochemical
cycling interacts with marsh hydrology and geomorphology to determine physical and biological conditions
within a given wetland. Major chemical cycles in coastal
wetlands include those of nitrogen, sulfur, iron, manganese, carbon, and phosphorous.
160
COASTAL WETLANDS