Responses and Recovery of Salt Marsh Vegetation and Birds in Southeastern Massachusetts to Two Hydrologic Events: a Tidal Restoration and an Inundation Event

Abstract

Allens Pond, a coastal lagoon in southeastern Massachusetts, was subjected to two major hydrological events in the 2000s. The first was a culvert widening to increase tidal flushing in an attempt to stop the spread of the invasive plant, Phragmites australis. The second, four years later, was a complete inundation of the surrounding salt marsh due to the closure of a tidal inlet. The effect of these events on salt marsh vegetation was monitored using transects and on the marsh avian community using point counts. The inundation event, although limited to one growing season, had a more pronounced negative effect on marsh organisms than the restoration. Saltmarsh cordgrass, Spartina alterniflora, took approximately three years to recover to pre-inundation abundance. Salt marsh hay, Spartina patens, had still not recovered five years after the inundation. This supports the idea that this high marsh plant is particularly sensitive to prolonged inundation. There was no measurable effect of either the hydrological restoration or the inundation event on P. australis. Saltmarsh sparrows declined 79% in the years immediately following the inundation, then recovered to their pre-inundation level in about eight years. Seaside sparrows declined 49% immediately following the inundation event and recovered after eight years, although there was a great deal of variation. Willets were only affected in the year immediately after the inundation. Our results from this flooding incident at Allens Pond provide insight into the potential impact of rising sea levels on estuarine plant and avian communities.