ANNUAL REPORT ON ESTUARINE RESTORATION AT EAST HARBOR (TRURO, MA), CAPE COD NATIONAL SEASHORE, 2009
Technical Report NPS/NER/NRTR—2010/146

Stephen M. Smith, Kelly C. Medeiros,
Krista D. Lee, Sophia E. Fox,
and Holly K. Bayley

National Park Service
Cape Cod National Seashore, Wellfleet, MA

August 2010

U.S. Department of the Interior
National Park Service
Northeast Region
Philadelphia, Pennsylvania
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INTRODUCTION

To provide background and context for this report, which is the latest in a series of annual reports on East Harbor tidal restoration monitoring, the following has been excerpted from (Portnoy et al. 2008):

East Harbor, a 720-acre back-barrier lagoon comprised of Moon Pond, Pilgrim Lake and Salt Meadow, was artificially isolated from the Cape Cod Bay marine environment in 1868 with the filling of the original 1000-ft wide inlet at the northwest end of the system. A drainage system was installed at the south end of the embayment in 1894 to allow freshwater to escape. The exclusion of tides caused salinity to decline from a likely natural condition of 25-30 parts per thousand (ppt) to nearly freshwater conditions, at least by the time of the first documented fish survey in 1911. By this time the native estuarine fauna were largely extirpated; the State Survey of Inland Waters (1911) recorded “German carp and very few eels and shiners”. The blockage of tides apparently caused water quality to decline rapidly along with salinity: surveys from 1911 to the 1970s reported low salinity (4-10 ppt), high turbidity, probably due to carp feeding and cyanobacterial blooms (Mozgala 1974), nuisance chironomid midge breeding and chronic summertime dissolved oxygen stress (Emery & Redfield 1969, Cape Cod National Seashore 2002).

An oxygen depletion and fish kill in September 2001 prompted Truro and Cape Cod National Seashore officials to open the clapper valves in the 4-ft diameter drainage pipe connecting the southeast end of the system (Moon Pond) with Cape Cod Bay (Fig. A) in hopes of restoring some tidal exchange and increasing aeration. These valves have been cabled open almost continuously from November 2002 to the present. Despite limits on tidal exchange imposed by the pipe’s small diameter, and the distance that it travels under ground, we have observed an> impressive response in the recovery of salinity and estuarine biota.

This report is a summary of monitoring results from 2009 on hydrology, water quality, submerged and emergent vegetation, and nekton (fish and decapod crustaceans). No benthic invertebrate sampling was done in 2009. For more details on monitoring methodologies and results, please refer to previous reports (Portnoy et al. 2005-2008) – now available online at: http://www.nps.gov/caco/naturescience/east-harbor-tidal-restoration-project-page.htm .

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