Quadrat-based measurements of eelgrass shoot density and above-ground biomass for plants growing in shallow and deep zones at four coastal sites in Massachusetts, USA in 2019

This dataset includes quadrat-based measurements of eelgrass shoot density and above-ground biomass for plants growing in shallow and deep zones at four different sites in Massachusetts, USA in 2019. The four sites were West Beach in Beverly (N 42.55921, W 70.80578), Curlew Beach in Nahant (N 42.42009, W 70.91553), Lynch Park in Beverly (N 42.54488, W 70.85842), and Niles Beach in Gloucester (N 42.59711, W 70.65592). Like many marine foundation species, eelgrass often spans strong environmental gradients over relatively small spatial scales - this data set provides information on phenotypic differentiation across the depth gradient at multiple sites in the Gulf of Maine.