Dataset: Number and mass of eelgrass seeds collected from sediment cores in shallow and deep zones at four coastal sites in Massachusetts, USA in 2019

Location description: Four coastal sites in the Gulf of Maine, USA, that sustain continuous eelgrass meadows across a depth gradient of ~1-2 m below MLLW to ~4-5.5 m below MLLW (see Supplemental File "Site List" for site codes used in this dataset and coordinates (lat,lon)).

Divers on SCUBA cored for dispersed eelgrass seeds at four different eelgrass beds in Massachusetts in September 2019, within the same permanent sampling grids established and sampled for shoot density and morphology earlier in the summer. 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), and cores were collected in permanent quadrats previously established in both the shallow and deep zone at each site, defined by proximity to the respective edges of the eelgrass beds. 

Each core was 10 cm in diameter and 10 cm in depth; divers collected cores at 3 locations within each grid at Curlew Beach, and at 4 locations within each grid at the other three field sites (n = 9 or 12 cores per depth). The sediment cores were bagged and kept cold (4ºC) until they could be processed; each core was hand-sieved for intact seeds within three days of collection. We counted all intact seeds encountered and assessed viability by firmness. Seeds that were deemed viable were individually weighed and stored in microfuge tubes and frozen at -80ºC until DNA extraction.

Organism: 
eelgrass, Zostera marina, urn:lsid:marinespecies.org:taxname:495077