Salt Marsh Restoration in Connecticut: 20 Years of Science and Management

Warren, R.

In 1980 the State of Connecticut began a tidal marsh restorationprogram targeting systems degraded by tidal restrictions andimpoundments. Such marshes become dominated by common reedgrass (Phragmites australis) and cattail (Typha angustifolia and T.latifolia), with little ecological connection to Long Island Sound. Themanagement and scientific hypothesis was that returning tidal action,reconnecting marshes to Long Island Sound, would set these systemson a recovery trajectory. Specific restoration targets (Le., pre-disturbanceconditions or particular reference marshes) were considered unrealistic.However, it was expected that with time restored tides would returnecological functions and attributes characteristic of fully functioning tidalsalt marshes. Here we report results of this program at nine separatesites within six marsh systems along 110 km of Long Island Soundshoreline, with restoration times of 5 to 21 years. Biotic parametersassessed include vegetation, macroinvertebrates, and use by fish andbirds. Abiotic factors studied were soil salinity, elevation and tidalflooding, and soil water table depth. Sites fell into two categories ofvegetation recovery: slow, ca. 0.5%, or fast, more than 5% of total areaper year. Although total cover and frequency of salt marsh angiospermswas positively related to soil salinity, and reed grass stand parametersnegatively so, fast versus slow recovery rates could not be attributed tosalinity. Instead, rates appear to reflect differences in tidal flooding.Rapid recovery was characterized by lower elevations, greaterhydroperiods, and higher soil water tables. Recovery of other bioticattributes and functions does not necessarily parallel those forvegetation. At the longest studied system (rapid vegetation recovery) thehigh marsh snail Melampus bidentatus took two decades to reachdensities comparable with a nearby reference marsh, whereas theamphipod Orchestia grillus was well established on a slow-recoverymarsh, reed grass dominated after 9 years. Typical fish speciesassemblages were found in restoration site creeks and ditches within 5years. Gut contents of fish in ditches and on the high marsh suggest thatuse of restored marsh as foraging areas may require up to 15 years toreach equivalence with reference sites. Bird species that specialize insalt marshes require appropriate vegetation; on the oldest restorationsite, breeding populations comparable with reference marshland hadbecome established after 15 years. Use of restoration sites by birdsconsidered marsh generalists was initially high and was still nearly twicethat of reference areas even after 20 years. Herons, egrets, and

Salt Marsh Restoration in Connecticut: 20 Years of Science and Management

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