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Providing evidence to improve practice

Individual study: Molluscan community recovery following partial tidal restoration of a New England estuary, U.S.A.

Published source details

Thelen B.A. & Thiet R.K. (2009) Molluscan community recovery following partial tidal restoration of a New England estuary, U.S.A. Restoration Ecology, 17, 695-703


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Restore coastal lagoons Subtidal Benthic Invertebrate Conservation

A study in 2005 in a lagoon connected to Cape Cod Bay, Massachusetts, USA (Thelen & Thiet 2009 – same experimental set-up as Thiet et al. 2014) found that, three years after restoring its connection to the sea, molluscs had recolonised the lagoon, but molluscan abundance and species richness significantly varied within the lagoon, increasing with salinity and proximity to its connection to the sea. Sixteen molluscan species were recorded across the lagoon. Species richness in Moon Pond (13 species; highest salinity; closest to the sea) was significantly higher than in the central lagoon (9 species; intermediate salinity and distance to the sea) and the northwest cove (2 species, lowest salinity and furthest from the sea). Total mollusc abundance varied spatially within the lagoon, from 0.3 to 3,470 individuals/m2. Abundance of four selected species (softshell clam Mya arenaria; northern quahog Mercenaria mercenaria; blue mussel Mytilus edulis; periwinkle Littorina sp.) followed the same spatial pattern as species richness (see paper for details).  In 2002, tidal flow was partially restored to East Harbor lagoon (dominated by freshwater) by opening a culvert connecting to Cape Cod. Previously, no molluscan species were reported. In summer 2005, locations within three areas of the lagoon were surveyed twice (Moon Pond: 10 locations; central lagoon: 30 locations; northwest cove: 10 locations) using cores (0.79 m2) and quadrats (0.45 m2). Molluscs (>2 mm in cores; >0.64 cm in quadrats) were identified and counted. Salinity was measured at each location.

(Summarised by Anaëlle Lemasson)