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-15-2649-2018

Cited by 110 publications

(157 citation statements)

References 55 publications

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“…Specifically we predict to see the largest increase in cumulative hypoxic volume between oxygen concentrations of 2 and 5 mg l −1 [12], which is too hypoxic for many marine species to inhabit [13]. This flux of hypoxic water that typically occurs midsummer is expected to occur earlier in the year as well [12].…”

Section: Introductionmentioning

confidence: 90%

In the face of climate change and exhaustive exercise: the physiological response of an important recreational fish species

Crear¹,

Brill²,

Averilla

et al. 2020

R. Soc. open sci.

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Cobia (Rachycentron canadum) support recreational fisheries along the US mid-and south-Atlantic states and have been recently subjected to increased fishing effort, primarily during their spawning season in coastal habitats where increasing temperatures and expanding hypoxic zones are occurring due to climate change. We therefore undertook a study to quantify the physiological abilities of cobia to withstand increases in temperature and hypoxia, including their ability to recover from exhaustive exercise. Respirometry was conducted on cobia from Chesapeake Bay to determine aerobic scope, critical oxygen saturation, ventilation volume and the time to recover from exhaustive exercise under temperature and oxygen conditions projected to be more common in inshore areas by the middle and end of this century. Cobia physiologically tolerated predicted mid-and end-of-century temperatures (28-32°C) and oxygen concentrations as low as 1.7-2.4 mg l −1 . Our results indicated cobia can withstand environmental fluctuations that occur in coastal habitats and the broad environmental conditions their prey items can tolerate. However, at these high temperatures, some cobia did suffer post-exercise mortality. It appears cobia will be able to withstand near-future climate impacts in coastal habitats like Chesapeake Bay, but as conditions worsen, catch-and-release fishing may result in higher mortality than under present conditions.

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Section: Introductionmentioning

confidence: 90%

In the face of climate change and exhaustive exercise: the physiological response of an important recreational fish species

Crear¹,

Brill²,

Averilla

et al. 2020

R. Soc. open sci.

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show abstract

“…For warming scenarios, we consider temperature increases consistent with previous studies of climate change in the Gulf (Justi c et al 1996. For scenarios combining nutrient decreases and higher water temperatures, we select +2°C, congruous with other studies of hypoxia under climate change projections (Justi c et al 1996, Del Giudice et al 2018b, Irby et al 2018. Scenarios consider the effect of temperature on both oxygen saturation (O s ) and benthic respiration (D s ) through the mechanisms described above.…”

Section: Scenario Projectionsmentioning

confidence: 99%

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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“…This leads to the question of whether or not these results would stand if climate change impacts were added to the analysis. Although this study demonstrated that the current regulatory nutrient reductions are likely to eventually produce the required DO improvements under the present climate, it is not clear that the established nutrient loads will be adequate under near-term future climate conditions that include rising temperature and sea level along with changes in precipitation patterns (Irby et al 2018).…”

Section: Discussionmentioning

confidence: 77%

Evaluating Confidence in the Impact of Regulatory Nutrient Reduction on Chesapeake Bay Water Quality

Irby

Friedrichs

2018

Estuaries and Coasts

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Excess nutrients derived from anthropogenic activity have resulted in the degradation of coastal water quality and an increase in low-oxygen and hypoxic events worldwide. In an effort to curb these impacts and restore water quality in the Chesapeake Bay, a maximum load of nutrients has been established based on a framework of regulatory standards and models. This research aims to evaluate the projected changes in water quality resulting from the implementation of these nutrient reductions by applying the regulatory methodology to two different models that have been previously shown to have similar model skill. Results demonstrate that although the two models differ structurally and produce a different degree of absolute change, they project a similar relative improvement in water quality along the main stem of the Chesapeake Bay and the lower reaches of the tributaries. Furthermore, the models largely agree on the attainment of regulatory water quality standards as a result of nutrient reduction, while also establishing that meeting water quality standards is relatively independent of hydrologic (wet/dry) conditions. By developing a Similarity Index that compares model results across habitat, time, and methodology, this research identifies the locations and causes of greatest uncertainty in modeled projections of water quality. Although there are specific locations and times where the models disagree, overall this research lends support and increased confidence to the appropriateness of the nutrient reduction levels and in the general impact of nutrient reduction on Chesapeake Bay water quality under current environmental conditions.

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

Cited by 110 publications

References 55 publications

In the face of climate change and exhaustive exercise: the physiological response of an important recreational fish species

In the face of climate change and exhaustive exercise: the physiological response of an important recreational fish species

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

Evaluating Confidence in the Impact of Regulatory Nutrient Reduction on Chesapeake Bay Water Quality

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