Seasonal controls on nearshore dissolved oxygen variability and hypoxia in a coastal embayment

Walter, Ryan; Huie, Stephen Alexander; Abraham, Jon Christian P.; Pasulka, Alexis L.; Davis, Kristen A.; Thomas, P. Connolly; Mazzini, Piero L. F.; Robbins, Ian

doi:10.1016/j.ecss.2022.108123

Cited by 3 publications

(5 citation statements)

References 74 publications

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“…Extreme events (MHWs/MCSs) can drive the decline of ecosystem engineers like giant kelp forests, drive range expansion of species, and lead to changes in primary productivity 15 , 47 – 49 . These events can also lead to multi-stressor systems whereby extreme temperature anomalies co-exist with biogeochemical extremes due to conditions (e.g., harmful algal blooms, eutrophication, upwelling and stratification) that can exacerbate coastal ocean acidification and hypoxia (OAH) risk in nearshore habitats 50 , 51 . Despite the threat to valuable ecosystems, there are limited studies of the drivers of extreme events in the very shallow nearshore region of EBUS 28 .…”

Section: Discussionmentioning

confidence: 99%

“…Despite the threat to valuable ecosystems, there are limited studies of the drivers of extreme events in the very shallow nearshore region of EBUS 28 . Moreover, it is expected that MHW/MCS exposure in different nearshore environments is likely to be highly variable due to the presence of marine microclimates, where variations in oceanographic conditions and species response to extreme events can be strikingly different over just a few kilometers 33 , 50 , 51 . Collectively, this study highlights the critical role that both basin-scale climate modes and regional upwelling play in predicting extreme events and shaping nearshore resilience in EBUS.…”

Section: Discussionmentioning

confidence: 99%

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Effects of basin-scale climate modes and upwelling on nearshore marine heatwaves and cold spells in the California Current

Dalsin,

Walter,

Mazzini

2023

Sci Rep

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Marine heatwaves and cold spells (MHWs/MCSs) have been observed to be increasing globally in frequency and intensity based on satellite remote sensing and continue to pose a major threat to marine ecosystems worldwide. Despite this, there are limited in-situ based observational studies in the very shallow nearshore region, particularly in Eastern Boundary Current Upwelling Systems (EBUS). We analyzed a unique dataset collected in shallow waters along central California spanning more than four decades (1978–2020) and assessed links with basin-scale climate modes [Pacific Decadal Oscillation (PDO) and El Niño (MEI)] and regional-scale wind-driven upwelling. We found no significant increase/decrease in MHW/MCS frequency, duration, or intensity over the last four decades, but did observe considerable interannual variability linked with basin-scale climate modes. Additionally, there was a decrease in both MHW/MCS occurrence during the upwelling season, and the initiation of individual MHWs/MCSs coincided with anomalous upwelling. Most notably, the co-occurrence of warm (cold) phases of the PDO and MEI with negative (positive) upwelling anomalies strongly enhanced the relative frequency of positive (negative) temperature anomalies and MHW (MCS) days. Collectively, both basin-scale variability and upwelling forcing play a key role in predicting extreme events and shaping nearshore resilience in EBUS.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of basin-scale climate modes and upwelling on nearshore marine heatwaves and cold spells in the California Current

Dalsin,

Walter,

Mazzini

2023

Sci Rep

Self Cite

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“…A DO threshold of 4.6 mg L −1 (147

μ

mol L −1 ) was chosen based on the results of a meta‐analysis that indicated biological effects are first apparent at this level (Vaquer‐Sunyer and Duarte 2008). It is important to note that these conditions are not universally stressful to all organisms, but the summary statistics provide insight into geographic and temporal variability in exposure to potentially stressful conditions relevant to a wide range of marine organisms in the California current system (Gray et al 2002; Mattiasen et al 2020; Walter et al 2022). Thus, these analyses provide a heuristic process for characterizing exposure to extreme conditions in a spatially and temporally variable environment.…”

Section: Methodsmentioning

confidence: 99%

“…For example, DO concentrations at the surface may primarily be driven by source waters in areas of intense, persistent upwelling (and therefore linked to pH). In contrast, DO concentrations may be primarily driven by sea surface temperature in areas of weaker upwelling where the DO in upwelled waters has time to equilibrate with the atmosphere at the surface (Levin 2018; Walter et al 2022). The difference in gas exchange rates between oxygen vs. CO 2 can lead to a quicker equilibration of oxygen with the atmosphere and a decoupling of pH and DO.…”

mentioning

confidence: 99%

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Exposure to extremes in multiple global change drivers: Characterizing pH, dissolved oxygen, and temperature variability in a dynamic, upwelling dominated ecosystem

Kroeker

Donham

Vylet

et al. 2023

Limnology & Oceanography

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In upwelling systems, fluctuations in seawater pH, dissolved oxygen (DO), and temperature can expose species to extremes that differ greatly from the mean conditions. Understanding the nature of this exposure to extremes, including how exposure to low pH, low DO concentrations, and temperature varies spatiotemporally and in the context of other drivers, is critical for informing global change biology. Here, we use a 4-yr time series of coupled pH, DO, and temperature observations at six nearshore kelp forest sites spanning the coast of California to characterize the variability and covariance among these drivers. We further compare observed properties to those derived from a high-resolution coupled physical-biogeochemical simulation for the central California current system. We find the intensity, duration, and severity of exposure to extreme conditions beyond heuristic, biologically relevant pH T (< 7.7), and DO (< 4.6 mg L À1 ) values were greatest at sites with strong upwelling. In contrast, sites with relatively weaker upwelling had little exposure to pH or DO conditions below these heuristic values but had higher and more variable temperature. The covariance between pH, DO, and temperature was highest in sites with strong upwelling and weakest in sites with limited upwelling. These relationships among pH, DO, and temperature at the observation locations were mirrored in the model, and model output highlighted geographic differences in exposure regimes across the California marine protected area network. Together, these results provide important insight into the conditions marine ecosystems are exposed to relevant to studies of global change biology.

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Compound marine cold spells and hypoxic events in a nearshore upwelling system

Walter,

Dalsin,

Mazzini

et al. 2024

Estuarine, Coastal and Shelf Science

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Seasonal controls on nearshore dissolved oxygen variability and hypoxia in a coastal embayment

Cited by 3 publications

References 74 publications

Effects of basin-scale climate modes and upwelling on nearshore marine heatwaves and cold spells in the California Current

Effects of basin-scale climate modes and upwelling on nearshore marine heatwaves and cold spells in the California Current

Exposure to extremes in multiple global change drivers: Characterizing pH, dissolved oxygen, and temperature variability in a dynamic, upwelling dominated ecosystem

Compound marine cold spells and hypoxic events in a nearshore upwelling system

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