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Chapter 2 - Coastal EcosystemsShoreline armoring of all types (groins, bulkheading,rip rap, gambion, etc.) often causes direct loss of habitat,most often impacting adjacent properties (Nordstrom etal. 2003). There are legislative protections against dredging,filling, and bulkheading vegetated wetlands and/orsandy ocean beaches in some states. However, there isless protective legislation preventing the future armoringof shorelines in the sheltered coast. By their very nature,rocky shorelines are already hardened and more stable.With few exceptions, rocky coasts have been less subjectedto anthropogenic shoreline armoring, and when presentthese structures have less of an ecological impact thanthey do when they are constructed on more geologicallydynamic shoreline types.Oil SpillsOil spills are a significant threat to both marine and terrestrialwildlife along the shore. The potential threat oflarge-scale oil spills is related to the proximity of largeshipping, storage, and/or oil and gas exploration operations.Appropriate regulations and precautions can beused to mitigate the potential for harmful spills in areaswhere the drilling and transport of oil occurs. ESI mapsfeatures sensitive to oil spills to facilitate rapid response.Invasive SpeciesNew exotic marine species can have major impacts on marineand coastal systems through competition with nativespecies, predation (e.g. green crabs on clams), or actualhabitat impacts. By the time they are detected, marineinvasive species are virtually impossible to eradicate. Theecological consequences of recent marine invasions in thisregion are uncertain. Global shipping and aquaculture arethe main vectors for introduction of exotic marinespecies and marine disease invasions. In salt marshes, theEuropean genotype of common reed (Phragmites australis)is an aggressive competitor capable of forming densemonocultures that crowd out native salt-tolerant plantcommunities.Sea Level RiseAccelerated sea level rise due to global warming is a threatto all coastal targets. An in-depth look at this topic is addressedin the following section.Seagrass MeadowsThe mechanisms of seagrass loss can be characterizedas direct or indirect. Examples of direct mechanisms includethe uprooting of plants while harvesting shellfish,destruction of plants when motorized boats run aground,and a species-specific “wasting disease” which decimatedmany eelgrass beds in the last century. There is more uncertaintyin the assessment of indirect threats to seagrass,some of which are correlated with each other and are likelyto have cumulative and synergistic impacts, such as thedirect physiological impacts of increased nutrient loadingand the consequences of shading by chronic algal bloomsand excessive siltation. Threats which characteristicallyimpact the grasses’ key ecological attributes include eutrophication,algal blooms, alterations to water temperatureregime, benthic organism harvest methods, boating activities,shoreline armoring and impediments to naturalsediment movements, barrier island and inlet stabilizationapproaches, invasive species (especially green crabs), toxins,excessive macroalgae, altered seed predation regime,dredging, decreased abundance of native shellfish, disease,and herbivory.Nearshore ShellfishFive critical threats to nearshore shellfish assemblages inthe Northwest Atlantic region were identified:OverharvestEvidence of harvest of oysters, bay scallops, hard clams,and softshell clams, all valuable commercial species today,precedes written history. Despite management by stateagencies, many historic populations have been exploitedto levels too low for successful regeneration. For oysters,long-term harvest reports show that landings may havepeaked for some regions as early as the 1880s (Stanleyand Sellers 1986; Kirby 2004). Recent data show oysterlandings on the United States East Coast at a mere 2% ofhistoric highs (Eastern Oyster Biological Review Team2-42Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report