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Pamlico Sound, a large back‐barrier estuary in North Carolina, is under threat of climate change due to increased storm activity and sea level rise. The response of this system is investigated by considering what has already happened during changes in sea level over the late Holocene epoch. The hydrodynamic changes that occurred in response to geomorphic evolution are simulated using a 3‐D numerical model for four distinct “time‐slice” scenarios. To accomplish this, the present‐day bathymetry was obtained from a high‐resolution digital elevation model, and paleobathymetric grids were developed from sediment cores and seismic observations. Using the same hydrodynamic forcing for each geomorphic scenario, the models are compared to assess the combined response to: different inlets connecting the back‐barrier estuary to the ocean, changes in basin geomorphology due to sedimentation, and sea level rise. The results indicate that these factors have a considerable effect on hydrodynamics, waves, and salinity in the estuary. The time‐averaged tidal ranges were up to 3 times as high for the past environments in comparison with present‐day water level elevations, and maximum current velocities were over 3 times higher in regions close to paleo‐inlets. The simulations for each time slice suggest that the salinity distribution in Pamlico Sound is strongly influenced by the hydraulic connectivity with other estuaries and the number and size of tidal inlets through the barrier island system. The results indicate that changes to barrier systems induce strong, nonuniform, and complex responses in back‐barrier estuaries with regime shifts in hydrodynamic energy and water mass properties. A modeling approach is developed for simulating the response of an estuary to different geomorphological conditions over a long time scaleGeological observations were used to define inlet locations, basin morphology, and sea levels in the hydrodynamic modelThe results indicate controls on the water levels, current velocities, and salinity distributions in paleo‐estuarine environments

Research on benthic foraminifera during the Cenozoic era suggests a trial establishment period for originating species of up to two or three million years. However, extinction likelihood for species outlasting this trial period is the same despite differences in distribution-abundance-occurrance.

Recent benthic foraminifera distribution patterns form the basis of much palaeoenvironmental (particularly palaeobathymetric) interpretation used by geologists. We have recently summarized the distribution of recent benthic foraminifera on the Atlantic continental margin of North America1,2and report here the results of an analysis of all published data from the Gulf of Mexico. To obtain a synthesis of foraminiferal distribution in the Gulf of Mexico, a computerized catalogue of all published occurrences (presence or absence data) was compiled. Cluster analysis of these data isolated four large, marginally overlapping areas or provinces exhibiting a spatial correlation with Gulf of Mexico water masses. A fifth, smaller, discrete area (biofacies) was found at the mouth of the Mississippi delta.