The competing impacts of climate change and nutrient reductions on dissolved oxygen in Chesapeake Bay

Irby, Isaac D.; Friedrichs, Marjorie A. M.; Da, Fei; Hinson, Kyle E.

doi:10.5194/bg-2017-416

Cited by 22 publications

(63 citation statements)

References 42 publications

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“…Despite the differences among the three RCM projections, the projected increases in hypoxia in this eutrophic estuary are similar. This increase of 10–30% in the hypoxic and anoxic volumes is larger than the increases obtained from the model runs that considered simplified changes from climate model projections (Irby et al, ; Wang et al, ), suggesting possible nonlinear synergistic effects among different climate change factors.…”

Section: Discussionmentioning

confidence: 63%

“…The simplified climate change numerical experiments by Wang et al () and Irby et al () showed that sea level rise amplifies the estuarine transport and leads to stronger import of higher‐O 2 coastal water to the hypoxic region in the mid‐Bay. The net effect of sea level rise on estuarine hypoxia ultimately depends on the competition between the stronger vertical stratification and stronger inflows and is the subject of an ongoing model intercomparison study.…”

Section: Discussionmentioning

confidence: 99%

“…Summer anoxic volume was estimated to increase by 1.4% due to warming, but sea level rise resulted in a 12% reduction in the anoxic volume. In addition to warming and sea level rise, Irby et al () considered the effects of altered river flows. They found that warming reduced oxygen solubility year around, changes in precipitation and river flow fueled increased primary production, and sea level rise increased bottom‐water O 2 but decreased O 2 at mid‐depths.…”

Section: Introductionmentioning

confidence: 99%

“…They found that warming reduced oxygen solubility year around, changes in precipitation and river flow fueled increased primary production, and sea level rise increased bottom‐water O 2 but decreased O 2 at mid‐depths. Irby et al () found that the overall impact of climate change will be to lower O 2 in Chesapeake Bay, but its potential impact is significantly smaller than the improvement in O 2 due to planned nutrient reductions.…”

Section: Introductionmentioning

confidence: 99%

“…This multimodel projection would generate probabilistic and practical impact assessment. However, this approach has not yet been implemented in Chesapeake Bay; previous studies were only based on sensitivity analyses to individual climate change factors or their combined effects (Irby et al, ; Wang et al, ). They cannot be directly used to make projections for estuarine hypoxia for the future climate.…”

Section: Introductionmentioning

confidence: 99%

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Large Projected Decline in Dissolved Oxygen in a Eutrophic Estuary Due to Climate Change

Ross

et al. 2019

JGR Oceans

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Climate change is known to cause deoxygenation in the open ocean, but its effects on eutrophic and seasonally hypoxic estuaries and coastal oceans are less clear. Using Chesapeake Bay as a study site, we conducted climate downscaling projections for dissolved oxygen and found that the hypoxic and anoxic volumes would increase by 10-30% between the late 20th and mid-21st century. A budget analysis of dissolved oxygen in the bottom water revealed differing physical and biogeochemical responses to climate change. Sea level rise and larger winter-spring runoff led to stronger stratification and large reductions in the vertical oxygen supply to the bottom water. On the other hand, warming led to earlier initiation of hypoxia, accompanied by weaker summer respiration and more rapid termination of hypoxia. Decreasing solubility due to warming accounted for about 50% of the reduction in the bottom-water oxygen content.

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Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Large Projected Decline in Dissolved Oxygen in a Eutrophic Estuary Due to Climate Change

Ross

et al. 2019

JGR Oceans

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Bayesian mechanistic modeling characterizes Gulf of Mexico hypoxia: 1968–2016 and future scenarios

Giudice

Matli

Obenour

2019

Ecological Applications

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The hypoxic zone in the northern Gulf of Mexico is among the most dramatic examples of impairments to aquatic ecosystems. Despite having attracted substantial attention, management of this environmental crisis remains challenging, partially due to limited monitoring to support model development and long‐term assessments. Here, we leverage new geostatistical estimates of hypoxia derived from nearly 150 monitoring cruises and a process‐based model to improve characterization of controlling mechanisms, historic trends, and future responses of hypoxia while rigorously quantifying uncertainty in a Bayesian framework. We find that November–March nitrogen loads are important controls of sediment oxygen demand, which appears to be the major oxygen sink. In comparison, only ~23% of oxygen in the near‐bottom region appears to be consumed by net water column respiration, which is driven by spring and summer loads. Hypoxia typically exceeds 15,600 km2 in June, peaks in July, and declines below 10,000 km2 in September. In contrast to some previous Gulf hindcasting studies, our simulations demonstrate that hypoxia was both severe and worsening prior to 1985, and has remained relatively stable since that time. Scenario analysis shows that halving nutrient loadings will reduce hypoxia by 37% with respect to 13,900 km2 (1985–2016 median), while a +2°C change in water temperature will cause a 26% hypoxic area increase due to enhanced sediment respiration and reduced oxygen solubility. These new results highlight the challenges of achieving hypoxia reduction targets, particularly under warming conditions, and should be considered in ecosystem management.

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Dermal mycobacteriosis and warming sea surface temperatures are associated with elevated mortality of striped bass in Chesapeake Bay

Groner

Hoenig

Pradel

et al. 2018

Ecology and Evolution

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Temperature is hypothesized to alter disease dynamics, particularly when species are living at or near their thermal limits. When disease occurs in marine systems, this can go undetected, particularly if the disease is chronic and progresses slowly. As a result, population‐level impacts of diseases can be grossly underestimated. Complex migratory patterns, stochasticity in recruitment, and data and knowledge gaps can hinder collection and analysis of data on marine diseases. New tools enabling quantification of disease impacts in marine environments include coupled biogeochemical hydrodynamic models (to hindcast key environmental data), and multievent, multistate mark–recapture (MMSMR) (to quantify the effects of environmental conditions on disease processes and assess population‐level impacts). We used MMSMR to quantify disease processes and population impacts in an estuarine population of striped bass (Morone saxatilis) in Chesapeake Bay from 2005 to 2013. Our results supported the hypothesis that mycobacteriosis is chronic, progressive, and, frequently, lethal. Yearly disease incidence in fish age three and above was 89%, suggesting that this disease impacts nearly every adult striped bass. Mortality of diseased fish was high, particularly in severe cases, where it approached 80% in typical years. Severely diseased fish also had a 10‐fold higher catchability than healthy fish, which could bias estimates of disease prevalence. For both healthy and diseased fish, mortality increased with the modeled average summer sea surface temperature (SST) at the mouth of the Rappahannock River; in warmer summers (average SST ≥ 29°C), a cohort is predicted to experience >90% mortality in 1 year. Regression of disease signs in mildly and moderately diseased fish was <2%. These results suggest that these fish are living at their maximum thermal tolerance and that this is driving increased disease and mortality. Management of this fishery should account for the effects of temperature and disease on impacted populations.

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The competing impacts of climate change and nutrient reductions on dissolved oxygen in Chesapeake Bay

Cited by 22 publications

References 42 publications

Large Projected Decline in Dissolved Oxygen in a Eutrophic Estuary Due to Climate Change

Large Projected Decline in Dissolved Oxygen in a Eutrophic Estuary Due to Climate Change

Bayesian mechanistic modeling characterizes Gulf of Mexico hypoxia: 1968–2016 and future scenarios

Dermal mycobacteriosis and warming sea surface temperatures are associated with elevated mortality of striped bass in Chesapeake Bay

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