Mitigating Shore Erosion Along Sheltered Coasts (2007) / Chapter Skim
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4 Mitigating Eroding Sheltered Shorelines: A Trade Off in Ecosystem Services
4 Mitigating Eroding Sheltered Shorelines: A Trade Off in Ecosystem Services
Pages 78-97
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From page 78... ...
. This chapter focuses on the trade-off of ecosystem services associated with shoreline protection methods, i.e., the loss of ecosystem services of natural coastal communities along sheltered coasts that are being protected from further erosion and the gain of ecosystem services associated with man-made structures built to protect the shoreline from erosion.
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From page 79... ...
. The current trend of enhanced shoreline erosion and subsequent shoreline protection (see Tables 4-1 and 4-2)
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From page 80... ...
ECOSYSTEM SERVICES PROVIDED BY NATURAL COASTAL SYSTEMS This consideration of coastal systems focuses on those that are subject to erosion on sheltered shorelines. These are either constructional coastal features such as beaches, dunes, mudflats, and vegetated communities (both intertidal and subtidal)
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From page 81... ...
FIGURE 4-1 Conceptual diagram of a beach emphasizing its importance along sheltered coasts and outlining processes that occur on beaches. Habitat These sheltered coastal environments provide habitat for a variety of organisms.
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From page 82... ...
Recreation This is one of the most socially important services provided by beaches and dunes. Many sheltered shorelines, especially in estuaries, are close to urban areas, and large numbers of people take advantage of beaches and public access opportunities.
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From page 83... ...
. However, the placement of erosion control measures frequently have unintended consequences in reducing the ecosystem services provided both by proximal and distant beaches and dunes.
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From page 84... ...
, and salt marsh (next page) emphasizing their importance along sheltered coasts and outlining processes commonly observed in these communities.
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From page 85... ...
in the associated plant and animal communities. Ecosystem services of mudflats 4-2c and vegetated communities include: Habitat Marshes, mangroves, seagrasses and macroalgae serve as habitat for a large diversity of organisms from bacteria to mammals (e.g., sea otters in kelp beds)
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From page 86... ...
MITIGATING SHORE EROSION ALONG SHELTERED COASTS Food Production Coastal plant communities fuel the food web in shallow waters. Macroalgae are often directly consumed by organisms, such as sea urchins and herbivore fishes.
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From page 87... ...
If plant communities are allowed to erode, most of the ecosystem services they provide will be lost. Marshes Natural coastal wetlands provide a broad range of ecosystem services.
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From page 88... ...
. The ecosystem services provided by these restored or created habitats include all of those listed for natural systems, but it takes time for the systems to mature.
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From page 89... ...
As a result, ecosystem services have not been adequately documented, but are likely to include: Habitat Bluff habitat varies depending on differences in substrates, rainfall, wind exposure, and other physical factors. Bluffs, particularly forested bluffs, provide many unique and important habitat features.
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From page 90... ...
Overhanging vegetation can shade beach or marsh substrates and nearshore waters, reducing and regulating temperatures. This can have a significant affect on species living in the shaded habitat.
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From page 91... ...
The Impact of Shoreline Stabilizing Structures on Bluffs One of the major impacts of bluff stabilizing structures will be on the services provided by bluffs to downstream ecosystems, such as beaches and marshes. Bluffs are a source of groundwater, nutrients, sediments, and organic debris (i.e., leaves and trees)
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From page 92... ...
A summary of ecosystem services provided by the major types of shoreline protection structures is presented below and presented in Table 4-3. Bulkhead The location of the bulkhead is essential in determining its effect on its environment.
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From page 93... ...
Please note that the ecosystem services assigned to techniques to mitigate shoreline erosion are best estimates. Extensive research is still needed to determine the ecosystem services provided by these techniques.
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From page 94... ...
In summary, breakwaters may provide some ecosystem services related to fish, oyster, and plant habitat, and may contribute to primary production although to a limited degree. Breakwaters may also increase spatial biodiversity although this ecosystem service may not always be welcomed (i.e., introduction of new
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From page 95... ...
CUMULATIVE AND SECONDARY IMPACTS OF TECHNIQUES TO MITIGATE SHORELINE EROSION As in many instances of mitigation (NRC, 2001) , the cumulative effects of multiple shoreline structures or protection measures are rarely addressed.
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From page 96... ...
A large number of nearby structures can disrupt natural barriers (e.g., extensive sand beaches serve as a barrier for the dispersion of organisms associated with rocky shores) enhancing the dispersal of species characteristic of rocky shores in regions that were naturally poorly connected.
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From page 97... ...
need to be considered when developing a regional shoreline protection plan. FINDINGS • A general lack of information exists about the ecosystem services provided by structures to mitigate shoreline erosion.
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