Coastal inundation is affected not only by rising mean sea level but also by changing tides. A numerical model is developed to investigate how sea level rise and coastline changes may impact tides in two coastal‐plain estuaries, Chesapeake Bay and Delaware Bay. Despite their different tidal characteristics, the two estuaries display similar responses to the sea level rise and shoreline management scenarios. When hypothetic sea walls are erected at the present coastline to prevent low‐lying land from flooding, tidal range increases, with greater amplification in the upper part of the two estuaries. When low‐lying land is allowed to become permanently inundated by higher sea level, however, tidal range in both estuaries decreases. Analyses of the tidal energy budget show that the increased dissipation over the shallow water and newly inundated areas compensates for the reduced dissipation in deep water, leading to smaller tidal range. The changes in the tidal range are not proportional to the changes in the mean sea level, indicating a nonlinear tidal response to sea level rise. The ratio of tidal range change to sea level rise varies between −0.05 and 0.1 in Chesapeake Bay and between −0.2 and 0.25 in Delaware Bay. The model results suggest a potential adaptation strategy that uses inundation over low‐lying areas to reduce tidal range at up‐estuary locations.

Secular tidal trends are present in many tide gauge records, but their causes are often unclear. This study examines trends in tides over the last century in the Chesapeake and Delaware Bays. Statistical models show negative M2 amplitude trends at the mouths of both bays, while some upstream locations have insignificant or positive trends. To determine whether sea level rise is responsible for these trends, we include a term for mean sea level in the statistical models and compare the results with predictions from numerical and analytical models. The observed and predicted sensitivities of M2 amplitude and phase to mean sea level are similar, although the numerical model amplitude is less sensitive to sea level. The sensitivity occurs as a result of strengthening and shifting of the amphidromic system in the Chesapeake Bay and decreasing frictional effects and increasing convergence in the Delaware Bay. After accounting for the effect of sea level, significant negative background M2 and S2 amplitude trends are present; these trends may be related to other factors such as dredging, tide gauge errors, or river discharge. Projected changes in tidal amplitudes due to sea level rise over the 21st century are substantial in some areas, but depend significantly on modeling assumptions.

Tropical and extratropical storms commonly occur in the Northwest Atlantic Ocean, sometimes causing catastrophic losses to coastal fisheries. Still, their influence on fish movements and range shifts is poorly known. We coupled biotelemetry observations of black sea bass in the U.S. Mid-Atlantic Bight with numerical modelling of the coastal ocean to evaluate the influence of Hermine (3–8 September 2016) on cold pool thermal destratification and fish evacuation. Spring through fall, black sea bass is a sedentary species, with movements focused on structure where they support important commercial and recreational fisheries. During summer 2016, we characterized the movements of 45 acoustically tagged black sea bass at three sites deploying acoustic receivers moored in shelf waters 18–31 km east of Ocean City, Maryland, and at depths 20–32 m in the southern Mid-Atlantic Bight. On 3 September 2016, cyclonic winds of Hermine caused rapid destratification of the water column. At experimental sites, bottom temperatures rose from 13 to 23°C in 10 h. An oceanographic model and observing data showed that the effects of this destratification dominated large portions of the Mid-Atlantic Bight and had long term effects on seasonal evolution of the shelf temperature. Nearly half of remaining black sea bass on 3 September (40%) permanently evacuated the experimental sites. Those that remained showed long-term depressed activity levels. Although the cause of this incomplete evacuation is unknown, it exemplifies partial migration, which may buffer black sea bass to regional impacts of changed timing or increased incidence of tropical storms.

Near‐inertial currents (NICs) were observed on the Mid‐Atlantic Bight (MAB) during the passage of Hurricane Arthur (2014). High‐frequency radars showed that the surface currents were weak near the coast but increased in the offshore direction. The NICs were damped out in 3–4 days in the southern MAB but persisted for up to 10 days in the northern MAB. A Slocum glider deployed on the shelf recorded two‐layer baroclinic currents oscillating at the inertial frequency. A numerical model was developed to interpret the observed spatial and temporal variabilities of the NICs and their vertical modal structure. Energy budget analysis showed that most of the differences in the NICs between the shelf and the deep ocean were determined by the spatial variations in wind energy input. In the southern MAB, energy dissipation quickly balanced the wind energy input, causing a rapid damping of the NICs. In the northern MAB, however, the dissipation lagged the wind energy input such that the NICs persisted. The model further showed that mode‐1 waves dominated throughout the MAB shelf and accounted for over 70% of the current variability in the NICs. Rotary spectrum analyses revealed that the NICs were the largest component of the total kinetic energy except in the southern MAB and the inner shelf regions with strong tides. The NICs were also a major contributor to the shear spectrum over an extensive area of the MAB shelf and thus may play an important role in producing turbulent mixing and cooling of the surface mixed layer.

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