Modeling hypoxia and its ecological consequences in Chesapeake Bay

Abstract

The Chesapeake Bay is a valuable recreational, ecological and economic resource that is subject to environmental hazards, such as harmful algal bloom (HAB) and hypoxia, which can degrade the Bay's health and jeopardize the viability of this important natural resource. As a step toward developing the capability to forecast such hazards, a biogeochemical version of the Chesapeake Bay Regional Ocean Modeling System (ChesROMS) has been developed. The model framework encompasses the physical, biogeochemical and bio-optical effects of river borne sediments, atmospheric deposition, nutrient and dissolved organic matter inputs, and benthic interactions throughout the Bay. These influences all contribute to the evolution of dissolved oxygen in the Bay's waters, in particular the consistent annual development of anoxia in the bottom waters of the mid-Bay region. Here, we report on the performance of a newly developed, mechanistic dissolved oxygen formulation that has been incorporated into the ChesROMS model with the motivation to realistically resolve seasonally developing hypoxia/anoxia in the Bay. Insights into various biophysical interactions and biogeochemical processes of the Bay gained from these numerical experiments are considered, and the application of the ChesROMS model fields in short-term ecological forecast applications is discussed.