Intertidal clam settlement in Washington state, USA

This dataset addresses the settlement rates of two non-native intertidal clam species at 8 beaches in Washington state, USA from May to September 2016-2017. Clam species were manila (Ruditapes philippinarum) and eastern soft-shell (Mya arenaria). Settlement was measured at mean tide level on shore every 2-4 weeks in mesh bags (1.5 mm mesh, 10x12 mm) filled with round gravel or crushed shell. Clams were counted that were caught on 250 micron sieve (large settlers) and, in 2016, on 150 micron mesh (small settlers). Also, in June 2017, densities of juvenile clams <20mm were measured at mean tidal elevation at each beach in five samples of 900 cm^2, 5 cm depth. Archived files include site locations and the date, site, position along transect at mean tide level, and counts of each clam species and size class. Data were used to test for spatio-temporal variation in settlement, to relate settlement timing and magnitude to local temperature and salinity, and to relate juvenile densities to settlement the previous year.