Use of settlement patterns and geochemical tagging to test population connectivity of eastern oysters Crassostrea virginica

Freshwater-dominated estuaries experience large fluctuations in their physical and chemical environments which may influence larval dispersal, settlement, connectivity of populations with pelagic stages. We used settlement patterns natural tagging along numerical hydrodynamic model results to assess among oysters across the freshwater-dominated Mobile Bay-eastern Mississippi Sound (MB-EMS) system. Specifically, we (1) tested how freshwater inputs associated environmental attributes influenced during high low discharge conditions 2014 2016, respectively, (2) analyzed trace element (TE) ratios incorporated into multiple shell types (larval settled spat adult shells) determine if shells collected situ incorporate temporally stable site-specific signatures. also assessed TE compared between (TE natal signature proxy) could infer connectivity. Larval was 4× higher than when oyster larvae only salinity regions (EMS). Spat that varied from weeks months. Connectivity (May-June 2016 only) suggest EMS is an important source lower MB. While were able probable using shells, more study needed utility as proxies for natal-location Results provide a baseline measuring future distribution changes MB-EMS Biological geochemical data demonstrate potential identify spatiotemporally mediate dynamic systems.