Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay

Abstract

Climate change represents an increasing stressor on estuarine and coastal ecosystems. A series of simulations were run using the Integrated Compartment Water Quality Model to determine the magnitude of various mechanisms controlling the effect of climate warming on dissolved oxygen (DO) in the Chesapeake Bay. The results suggested that the average hypoxic volume in the summer would increase by 9% (410 Mm3) from 1995 to 2025 as air temperature increases by 1.06°C and water temperature by 0.9°C. The change in DO solubility contributes 55% of the total climate warming effect, biological rates 33%, and stratification 11%. The Rappahannock Shoal, a hydraulic control point, plays a major role in determining the effect of climate warming on DO in the Bay. Due to the abrupt change in bathymetry, the convergence between seaward‐moving freshwater and landward‐moving saltwater causes downwelling and enhanced vertical mixing which introduces surface water of higher temperature to the deep channel and accelerates organic matter remineralization and oxygen consumption in deep waters. Surface water DO concentrations will decrease under climate warming conditions due to lower DO solubility, reducing DO flux to the deep channel and contributing to hypoxia development. These findings provide critical information for future management decision making regarding the effects of climate warming on DO in Chesapeake Bay and other estuaries.

Spatial differences in estuarine utilization by seasonally resident species in Mid‐Atlantic Bight, USA

“…For seasonal estuarine residents, the combination of distributional shifts, faster spring warming, and earlier spring onset may result in seasonal migrations that bypass Chesapeake Bay in favor of a more northern estuary. Furthermore, the lowered solubility of dissolved oxygen in warmer water temperatures is expected to cause an increase in the frequency, volume, and onset of hypoxia in this estuary (Irby et al, 2018;Najjar et al, 2010;Tian et al, 2021).…”

“…The Atlantic Ocean has been disproportionately impacted by warming (Cheng et al, 2020; Levitus et al, 2005), with temperatures increasing on the northwestern Atlantic shelf at rates nearly three times the global average (Saba et al, 2016). Adjacent estuaries along the East Coast of the United States also have been impacted by climate change, with systemic warming documented in Narragansett Bay (Collie et al, 2008; Langan et al, 2021; Oviatt, 2004), Long Island Sound (Howell & Auster, 2012), and Chesapeake Bay (Ding & Elmore, 2015; Hinson et al, 2021; Tian et al, 2021).…”

“…For seasonal estuarine residents, the combination of distributional shifts, faster spring warming, and earlier spring onset may result in seasonal migrations that bypass Chesapeake Bay in favor of a more northern estuary. Furthermore, the lowered solubility of dissolved oxygen in warmer water temperatures is expected to cause an increase in the frequency, volume, and onset of hypoxia in this estuary (Irby et al, 2018; Najjar et al, 2010; Tian et al, 2021). This phenomenon has been suggested as a critical factor driving distributional shifts in other ecosystems (Deutsch et al, 2015; Pörtner & Knust, 2007), and fish hypoxia avoidance behaviors have been documented within Chesapeake Bay (Buchheister et al, 2013) and elsewhere (Eby & Crowder, 2002).…”

Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia

“…Despite the relatively small magnitude of Chesapeake Bay watershed climate impacts on estuarine hypoxia compared to previous evaluations of other climate impacts, like atmospheric warming over the Bay (Irby et al, 2018;Ni et al, 2019;Tian et al, 2021), the relative contributions of ESM and downscaling effects to the total uncertainty are large and are also likely to expand the range of outcomes for other climate sensitivity studies in this region. This suggests that, when attempting to determine a likely range of ecosystem outcomes, selecting additional downscaling techniques and hydrological model responses should be considered in addition to the more common practice of only selecting multiple ESMs.…”

“…Future estimates of coastal hypoxia have increased substantially over the past decade, likely influenced by increased access to biogeochemical modeling tools and regional climate projections needed for finer scale modeling and analyses (Fennel et al, 2019). The majority of coastal hypoxia climate impact studies have focused on a select few coastal locations including the Baltic Sea (Meier et al, 2011a,b;Meier et al, 2012;Neumann et al, 2012;Ryabchenko et al, 2016;Saraiva et al, 2019a,b;Wåhlström et al, 2020;Meier et al, 2021;Meier et al, 2022), Chesapeake Bay (Wang et al, 2017;Irby et al, 2018;Ni et al, 2019;Testa et al, 2021;Tian et al, 2021;Cai et al, 2021), and the Gulf of Mexico (Justić et al, 1996;Justić et al, 2007;Lehrter et al, 2017;Laurent et al, 2018). Other projected changes to dissolved oxygen (O2) levels have been documented in nearshore environments including the North Sea (Meire et al, 2013;Wakelin et al, 2020), Arabian Sea (Lachkar et al, 2019), California Current System (Dussin et al, 2019;Siedlecki et al, 2021;Pozo Buil et al, 2021), and coastal waters surrounding China (Hong et al, 2020;Yau et al, 2020;Zhang et al, 2021;.…”