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Chapter 2 - Coastal EcosystemsNorthwest Atlantic Distributionand CharacterizationMethodsOverviewPrevious terrestrially-focused ecoregional assessmentsby TNC delineated specific beach and dune systems andtidal wetlands of regional importance based on their size,natural condition, and presence of rare nesting birds,plants or exemplary terrestrial natural communities.Unlike these earlier efforts, this assessment is the first tofocus on the coast from a marine perspective. To facilitatecharacterization of the entire coastline and potentialvalues of various subsets of the coast for marine processes,the coast was divided into 62 discrete stretches of shorelineand nearshore habitat (Coastal Shoreline Units, hereafterCSUs). These were stratified by subregions (Gulfof Maine, Southern New England, and the Mid-AtlanticBight), and by estuary type. Each unit in the United Statesportion fits into one of four Coastal Marine EcologicalClassification Standard (CMECS) types (Madden et al.2005) assigned by the Environmental Protection Agency(EPA) (Figure 2-7). The CMECS types of coastal areasare 1) river dominated, 2) lagoon, 3) coastal embayment,and 4) fjord. In addition, the relatively uniform Canadiancoastline within this region was characterized as the Bayof Fundy type. The CSUs of the region sorted into thefollowing categories:• Lagoons (7 examples)• Embayments (10 examples)• River-dominated (20 examples)• Fjords (18 examples)• Bay of Fundy (7 examples)Each discrete CSU delineates a segment of coast linetypically encompassing a large estuary or a set of smallinterconnected estuaries or a barrier beach and lagoon system.Each was characterized by summarizing a variety ofnatural features that have presumed relevance to how thecoastline contributes to marine productivity and biodiversity.These included:• Amount of tidal marshes (both salt and brackishemergent marsh)• Amount of eelgrass beds• Types of shellfish beds• Amount of beaches and dunes• Amount of rocky shores and cliffs• Number of salt ponds• Diversity of natural shoreline habitats• Importance to estuarine-dependent fish species• Importance to diadromous fish species• Importance to coastal breeding or wintering birdsIn addition, the condition of each CSU was summarizedwith respect to the amount of development, man-madeshoreline, and land use. It should be noted that the underlyingdata and methods for these characterizations couldbe applied to any geography, estuarine site classification, orstate for purposes of comparison.CMECS ClassificationThe CMECS classification focuses on the importanceof estuary size, shape, and flushing in dictating processeswithin an estuary and the adjacent coastal area. The classificationvariables are considered to be “natural” characteristicsof the estuary, in both material and energeticterms, meaning those which influence estuarine processingto varying degrees and are not generally controllableor influenced by either stressor or response variables.The types recognized in the CMECS classification are sodistinct in geomorphology and hydrology that they notonly look very different from each other, but also processnutrients in very different ways based on their exchangewith the ocean, fresh water inflow, and residence time.Although other coastal and estuarine classifications existin the region (Engle et al. 2007; Bricker et al. 2007), theCMECS classification brings together many local classificationsvia a standard format. The resultant classesprovide useful descriptors for biological and responsecharacteristics of the environment and are being used inthe forthcoming EPA e-Estuary project which will providea database and tools to support environmental decisionmakingfor estuaries (Detenbeck 2008, personal communication).2-18Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report