Intertidal eelgrass (Zostera marina) resilience traits in oyster aquaculture, US west coast

In spring and summer 2020-2022, intertidal sites differing in elevation, sediment conditions, and presence of oyster aquaculture were surveyed for eelgrass (Zostera marina) in estuaries along the U.S. west coast (Samish Bay, Hood Canal, Grays Harbor, Willapa Bay, Tillamook Bay, Humboldt Bay, Tomales Bay). Each bay included 1-6 sites. Each site included positions that differed in amount of eelgrass and presence of off-bottom or ground-cultured oysters. Each position was surveyed with 20 quadrats (0.25 m2) and by collection of up to 50 terminal shoots. At the quadrat level, data were recorded for vegetative and flowering shoot count and terminal shoot length. At the shoot level, data were recorded for shoot and sheath length, sheath width, above-ground dry mass, rhizome dry mass per length, internode length, and branching frequency at the four most recent rhizome nodes. All data are georeferenced in WGS84 datum.