Densities and cover data for intertidal organisms from an LTREB project in the Gulf of Maine, USA, from 1996 to 2023.

Experimental clearings in macroalgal (Ascophyllum nodosum) stands were made in 1996 to determine if mussel beds and macroalgal stands on protected intertidal shores in New England represent alternative community states. Uncleared control plots and four sizes of circular clearings (1m, 2m, 4m and 8m in diameter), which mimicked ice scour events, were established in A. nodosum stands at 12 sites on Swan’s Island, Maine, USA. The purpose of these datasets is to provide access to data on densities and percentage cover in the 60 experimental plots from 1996 to 2023. Earlier versions of the data prior to 2007 can be found in Ecological Archives ( E087-047 and E089-032). The current EDI version includes corrections of errors in the versions in Ecological Archives. Data include densities of mussels (Mytilus edulis), an herbivorous limpet (Testudinalia testudinalis), herbivorous snails (Littorina littorea, Littorina obtusata), a predatory snail (Nucella lapillus), a barnacle (Semibalanus balanoides), and fucoid algae (Ascophyllum nodosum and Fucus vesiculosus), and percentage cover by mussels, barnacles, fucoids and other sessile organisms. Research was funding by NSF's LTREB program.