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Chapter 2 - Coastal Ecosystemsstreams across the state found that “no segment of streamin Connecticut with > 12% Impervious Cover upstreamof the sampling location was able to meet ConnecticutWater Quality Standard for aquatic life” (CTDEP 2009).In contrast, the averages of proportion of developed landin Mid-Atlantic and Gulf of Maine watersheds are both9% and their average impervious surface only 2 and 3%respectively. The Mid-Atlantic, however, has much moreagriculture in most of its coastal watersheds. However,within each CMECS class and subregion there are someCSUs in very natural condition and others that are muchmore developed.A comparison with the NOAA National EstuarineEutrophication Assessment in some cases corroboratesand parallels the watershed land cover characterization,but not in all cases. For example, Massachusetts Bay, classifiedby NOAA as moderate to high overall eutrophication,has one of the highest percentages of impervious surface,23.7%. In contrast, the Neuse Riverine CSU in theMid-Atlantic is classified as having high overall eutrophicationalthough it is not among the highest in developed/agricultural land or impervious surface (Figure 2-19).Nearshore Shellfish DistributionFigure 2-9, 2-10, 2-11, and 2-12 show the reported 1995regional distribution of oysters, hard clams, softshellclams, and bay scallops, respectively. Recent landingsversus historic maxima are shown as shaded areas. Bluemussels and ribbed mussels are distributed throughout theregion, but spatial data are not available.With respect to shellfish species viability, we cautiously assertthat regional patterns of weak recent harvests relativeto benchmarks indicate low-density populations at riskof spawning failure in some areas. In particular, Easternoyster landings are < 10% of historic highs in eight of 11reporting states, and bay scallop landings are < 10% inall six reporting states. Hard clam landings are < 10% infour states and < 25% in three other states, also suggestingspawning limitations. Softshell clam populations may bein slightly better condition, with only five of 10 states reportingrecent landings < 25% of maxima.Human InteractionsNatural Shoreline CommunitiesMost of the coastal areas in the northern half of the regionwere covered with ice less than 20,000 years ago. Thisreality speaks to the adaptability and resilience of many ofthe plants and animals now using these habitats. Today,however, a variety of pressures, including oil spills, climatechange, invasive species introductions, eutrophication, andthe impending squeeze between the rising sea and humandevelopment are rapidly threatening the biological andhuman communities which rely upon our coasts andestuaries.Coastal DevelopmentThe squeeze of coastal habitats between human coastaldevelopment and sea level rise is and will continue tobe a major threat, as long as there is a societal desire toengineer less stable shoreline types in an effort to protectvulnerable real estate from inundation and erosion.Coastal development also brings with it increased inputsof nutrients and toxins, alterations of tidal flow, and overlandfreshwater input, all of which can impact shorelinesystems.Shoreline Stabilization, Altered SedimentRegimesBarrier islands and riverine deltas are the habitat typesprobably threatened most by storms and erosion, as theyare the most geologically unstable and therefore likely tobe impacted directly and indirectly by engineering thatalters natural sediment supplies. Alteration of sedimentdynamics by creation and maintenance of inlets to embayments,coastal salt ponds, and lagoons also impacts tidalamplitudes, residence times, temperature, and salinity, aswell as the export and import of dissolved and particulatenutrients for entire systems. At a smaller scale, channeldredging can impact adjacent shores as sediments accumulatein the deeper channels rather than near the adjacentshores. Similarly, nearshore sand mining can starvesome beaches of their natural sand supply in an attempt tonourish other beaches.2-40Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report