Summertime Interaction between the Chesapeake Bay and the Lower Choptank RiverEstuary: 1986-1987

摘要

Moored continuous sensors and semiweekly hydrographic surveys were operated insummer 1986 and 1987 in the lower Choptank River and adjacent Chesapeake Bay to: (1) determine the extent of low dissolved oxygen (DO) and possible impacts on oyster populations; (2) investigate the connection between low DO and the intrusion of saline water from the lower layer of the Chesapeake Bay; and (3) to examine the dynamics of lower layer intrusion. Intrusions of high salinity-low DO water into the lower Choptank from the sub-pycnocline Chesapeake Bay occur as wind-driven internal surges typically last 3-4 days. Intrusive pulses are driven primarily by tilting of the Bay pycnocline, when high salinity water is upwelled on the eastern side of the Bay following southerly wind stress. Advected low DO was not a problem for oyster populations in the lower Choptank during the low freshwater inflow years 1986-1987. The oyster bars were in areas too shallow to be directly affected by deep water intrusions; in wetter years, low DO water might be advected into shallower waters. Wind-forced transport of lower layer water from the Bay is a major source of saline, hypoxic, nutrient-rich water to the Choptank River estuary during summer.