Impacts on Estuarine Ecosystem from Climate Changes Based on Modeling Experiments within Delaware Bay

Abstract

Coastal regions concentrate ecological behaviors, have more observations, permit high-resolution modeling, and serve as a good climate-changing sensor. For the Delaware Bay, a high-resolution hydro-dynamical model (ROMS) was tailored, validated and applied to hindcast its largely unrecorded physical environment, to investigate the roles of the physical environment influencing oyster diseases, and to inquire into the future fate of the bay in response to climate changes. Sensitivity studies suggested that 50-100-cm sea-level rise (SLR) in approximately 50-100 years may occur and salinize the Delaware Bay mainly through weakening salinity gradient and salt advection due to the intensified mixing induced by the widened bay. Highly correlating to mixing and therefore changing salt advection, the width of the bay mattered to salt intrusion distance more than the depth of the bay did. This conclusion is differenet than that from the classic theories that emphasize the depth in influencing the salt intrusion distance via the steady shear dispersion. The SLR-induced salinization may not be offset by intensified river flow input, but may be substantially mitigated by fixing the coastline (or width). Climate warming may warm the shallow and thermally sensitive bay. The warm and salty conditions would compromise freshwater resource in the upper bay and be generally unfavorable to oysters by promoting oyster diseases (i.e., MSX and Dermo). Salinization might occur in other similar estuaries of narrow geometry, shallow depth, and small volume.