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  • 1
    Publication Date: 2022-05-26
    Description: Author Posting. © Association for the Sciences of Limnology and Oceanography, 2013. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 58 (2013): 1329–1343, doi:10.4319/lo.2013.58.4.1329.
    Description: Based on noninvasive eddy correlation measurements at a marine and a freshwater site, this study documents the control that current flow and light have on sediment–water oxygen fluxes in permeable sediments. The marine sediment was exposed to tidal-driven current and light, and the oxygen flux varied from night to day between −29 and 78 mmol m−2 d−1. A fitting model, assuming a linear increase in oxygen respiration with current flow, and a photosynthesis–irradiance curve for light-controlled production reproduced measured fluxes well (R2 = 0.992) and revealed a 4-fold increase in oxygen uptake when current velocity increased from ∼ 0 to 20 cm s−1. Application of the model to a week-long measured record of current velocity and light showed that net ecosystem metabolism varied substantially among days, between −27 and 31 mmol m−2 d−1, due to variations in light and current flow. This variation is likely typical of many shallow-water systems and highlights the need for long-term flux integrations to determine system metabolism accurately. At the freshwater river site, the sediment–water oxygen flux ranged from −360 to 137 mmol m−2 d−1. A direct comparison during nighttime with concurrent benthic chamber incubations revealed a 4.1 times larger eddy flux than that obtained with chambers. The current velocity during this comparison was 31 cm s−1, and the large discrepancy was likely caused by poor imitation by the chambers of the natural pore-water flushing at this high current velocity. These results emphasize the need for more noninvasive oxygen flux measurements in permeable sediments to accurately assess their role in local and global carbon budgets.
    Description: Support for this study was provided by the following National Science Foundation grants: OCE-0420575, OCE- 0536431, and OCE-1061364.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 2
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Long, M. H., Rheuban, J. E., McCorkle, D. C., Burdige, D. J., & Zimmerman, R. C. Closing the oxygen mass balance in shallow coastal ecosystems. Limnology and Oceanography, 64(6), (2019): 2694-2708, doi: 10.1002/lno.11248.
    Description: The oxygen concentration in marine ecosystems is influenced by production and consumption in the water column and fluxes across both the atmosphere–water and benthic–water boundaries. Each of these fluxes has the potential to be significant in shallow ecosystems due to high fluxes and low water volumes. This study evaluated the contributions of these three fluxes to the oxygen budget in two contrasting ecosystems, a Zostera marina (eelgrass) meadow in Virginia, U.S.A., and a coral reef in Bermuda. Benthic oxygen fluxes were evaluated by eddy covariance. Water column oxygen production and consumption were measured using an automated water incubation system. Atmosphere–water oxygen fluxes were estimated by parameterizations based on wind speed or turbulent kinetic energy dissipation rates. We observed significant contributions of both benthic fluxes and water column processes to the oxygen mass balance, despite the often‐assumed dominance of the benthic communities. Water column rates accounted for 45% and 58% of the total oxygen rate, and benthic fluxes accounted for 23% and 39% of the total oxygen rate in the shallow (~ 1.5 m) eelgrass meadow and deeper (~ 7.5 m) reef site, respectively. Atmosphere–water fluxes were a minor component at the deeper reef site (3%) but a major component at the shallow eelgrass meadow (32%), driven by diel changes in the sign and strength of atmosphere–water gradient. When summed, the measured benthic, atmosphere–water, and water column rates predicted, with 85–90% confidence, the observed time rate of change of oxygen in the water column and provided an accurate, high temporal resolution closure of the oxygen mass balance.
    Description: This work was substantially improved by comments from two anonymous reviewers. We thank Victoria Hill, David Ruble, Jeremy Bleakney, and Brian Collister for assistance in the field and the staff of the Bermuda Institute of Ocean Sciences and the Anheuser‐Busch Coastal Research Center for logistical support. This work was supported by NSF OCE grants 1657727 (to M.H.L. and D.C.M.), 1635403 (to R.C.Z. and D.J.B.), and 1633951 (to M.H.L.).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Rheuban, J. E., Doney, S. C., McCorkle, D. C., & Jakuba, R. W. Quantifying the effects of nutrient enrichment and freshwater mixing on coastal ocean acidification. Journal of Geophysical Research-Oceans, 124, (2019): 9085-9100, doi: 10.1029/2019JC015556.
    Description: The U.S. Northeast is vulnerable to ocean and coastal acidification because of low alkalinity freshwater discharge that naturally acidifies the region, and high anthropogenic nutrient loads that lead to eutrophication in many estuaries. This study describes a combined nutrient and carbonate chemistry monitoring program in five embayments of Buzzards Bay, Massachusetts to quantify the effects of nutrient loading and freshwater discharge on aragonite saturation state (Ω). Monitoring occurred monthly from June 2015 to September 2017 with higher frequency at two embayments (Quissett and West Falmouth Harbors) and across nitrogen loading and freshwater discharge gradients. The more eutrophic stations experienced seasonal aragonite undersaturation, and at one site, nearly every measurement collected was undersaturated. We present an analytical framework to decompose variability in aragonite Ω into components driven by temperature, salinity, freshwater endmember mixing, and biogeochemical processes. We observed strong correlations between apparent oxygen utilization and the portion of aragonite Ω variation that we attribute to biogeochemistry. The regression slopes were consistent with Redfield ratios of dissolved inorganic carbon and total alkalinity to dissolved oxygen. Total nitrogen and the contribution of biogeochemical processes to aragonite Ω were highly correlated, and this relationship was used to estimate the likely effects of nitrogen loading improvements on aragonite Ω. Under nitrogen loading reduction scenarios, aragonite Ω in the most eutrophic estuaries could be raised by nearly 0.6 units, potentially increasing several stations above the critical threshold of 1. This analysis provides a quantitative framework for incorporating ocean and coastal acidification impacts into regulatory and management discussions.
    Description: We thank Kelly Luis, Michaela Fendrock, Will Oesterich, Sheron Luk, Marti Jeglinksi, and Tony Williams for their help with field sample collection and logistical support and Chris Neill, Lindsay Scott, Rich McHorney, and Paul Henderson for laboratory sample analysis. We also thank the Waquoit Bay National Estuarine Research Reserve for loaning their handheld water quality meters and two anonymous reviewers for their feedback on this manuscript. Financial support for this work was provided by the John D. and Catherine T. MacArthur Foundation (grant no. 14‐106159‐000‐CFP), MIT Sea Grant (subaward 5710004045) and the West Wind Foundation. The data used in this analysis can be found in the NOAA NCEI repository for carbonate chemistry measurements, the Ocean Carbon Data System at the following link: https://www.nodc.noaa.gov/ocads/data/0206206.xml.
    Keywords: Coastal Acidification ; Eutrophication
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-10-26
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gassett, P. R., O’Brien-Clayton, K., Bastidas, C., Rheuban, J. E., Hunt, C., Turner, E., Liebman, M., Silva, E., Pimenta, A., Grear, J., Motyka, J., McCorkle, D., Stancioff, E., Brady, D., & Strong, A. Community science for coastal acidification monitoring and research. Coastal Management, 49(5), (2021): 510-531, https://doi.org/10.1080/08920753.2021.1947131.
    Description: Ocean and coastal acidification (OCA) present a unique set of sustainability challenges at the human-ecological interface. Extensive biogeochemical monitoring that can assess local acidification conditions, distinguish multiple drivers of changing carbonate chemistry, and ultimately inform local and regional response strategies is necessary for successful adaptation to OCA. However, the sampling frequency and cost-prohibitive scientific equipment needed to monitor OCA are barriers to implementing the widespread monitoring of dynamic coastal conditions. Here, we demonstrate through a case study that existing community-based water monitoring initiatives can help address these challenges and contribute to OCA science. We document how iterative, sequential outreach, workshop-based training, and coordinated monitoring activities through the Northeast Coastal Acidification Network (a) assessed the capacity of northeastern United States community science programs and (b) engaged community science programs productively with OCA monitoring efforts. Our results (along with the companion manuscript) indicate that community science programs are capable of collecting robust scientific information pertinent to OCA and are positioned to monitor in locations that would critically expand the coverage of current OCA research. Furthermore, engaging community stakeholders in OCA science and outreach enabled a platform for dialogue about OCA among other interrelated environmental concerns and fostered a series of co-benefits relating to public participation in resource and risk management. Activities in support of community science monitoring have an impact not only by increasing local understanding of OCA but also by promoting public education and community participation in potential adaptation measures.
    Description: AGU Centennial Grant NOAA OAP OFFICE North American Association for Environmental Education Curtis and Edith Munson Foundation Sea Grant programs within the region Senator George J. Mitchell Center for Sustainability Solutions Funding acknowledgment: MIT Sea Grant award NA18OAR4170105 to Bastidas NERACOOS The WestWind foundation (to Rheuban) Woods Hole Sea Grant (NOAA Grant No. NA18OAR4170104)
    Keywords: Ocean acidification ; Community science ; Citizen science ; Total alkalinity ; Water monitoring
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
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    Oceanography Society
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Lima, I.D., Rheuban, J.E. Gender differences in NSF ocean sciences awards. Oceanography 34(4), (2021), https://doi.org/10.5670/oceanog.2021.401.
    Description: In this study, we examine how women’s representation in National Science Foundation Ocean Sciences (NSF-OCE) awards changed between 1987 and 2019 and how it varied across different programs, research topics, and award types. Women’s participation in NSF-OCE awards increased at a rate of approximately 0.6% per year from about 10% in 1987 to 30% in 2019, and the strong similarity between the temporal trends in the NSF-OCE awards and the academic workforce suggests that there was no gender bias in NSF funding throughout the 33-year study period. The programs, topics, and award types related to education showed the strongest growth, achieving and surpassing parity with men, while those related to the acquisition of shared instrumentation and equipment for research vessels had the lowest women’s representation and showed relatively little change over time. Despite being vastly outnumbered by men, women principal investigators (PIs) tended to do more collaborative work and had a more diversified “portfolio” of research and research-related activities than men. We also found no evidence of gender bias in the amount awarded to men and women PIs during the study period. These results show that, despite significant increases in women’s participation in oceanography over the past three decades, women have still not reached parity with men. Although there appears to be no gender bias in funding decisions or amount awarded, there are significant differences between women’s participation in specific research subject areas that may reflect overall systemic biases in oceanography and academia more broadly. These results highlight areas where further investment is needed to improve women’s representation.
    Keywords: Ocean acidification ; Gulf of Maine ; Projection ; Regional simulations ; Species sensitivity ; Warming
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
    Publication Date: 2022-05-26
    Description: Author Posting. © Inter-Research, 2014. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 507 (2014): 1-13, doi:10.3354/meps10843.
    Description: The oxygen flux between benthic ecosystems and the overlying water column is a measure of metabolic status and a commonly used proxy for carbon cycling. In this study, oxygen flux was measured seasonally using the eddy correlation technique in a restored eelgrass (Zostera marina L.) meadow in the Virginia coastal bays (USA). In 5 intensive field campaigns, we covered seasonal variation in oxygen metabolism and biomass with overlap in late summer to observe interannual variability. The high-resolution measurements allowed identification of the drivers of metabolism at multiple timescales: minute to hourly, daily, and monthly to seasonally. There was a strong correlation between nighttime hourly fluxes and current velocity that varied seasonally with seagrass shoot density and temperature. No similar relationship was observed during the day. A hysteresis effect in oxygen flux throughout the day was observed during October and August that was most likely due to increased respiration (R) in the afternoon. In October, net community production was 90% lower in the afternoon than in the morning at the same irradiance. From this hysteresis, we calculated that daytime R may be up to 2.5-fold larger than nighttime R. The magnitudes of daily gross primary production (GPP) and R were well correlated throughout the year with close to a 1:1 ratio that reflected a tight coupling between GPP and R on daily to seasonal timescales. Our results document the dynamic nature of oxygen fluxes that, when integrated over time, translate into highly variable rates of ecosystem metabolism over daily to seasonal timescales. This variation must be incorporated to accurately determine trophic status.
    Description: Support for this study was provided by the University of Virginia and the National Science Foundation through grants from the Chemical Oceanography program (OCE-0536431 and OCE- 1061364) and the Division of Environmental Biology to the Virginia Coast Reserve Long Term Ecological Research Program (DEB-0621014 and DEB-1237733).
    Keywords: Zostera marina L. ; Net ecosystem metabolism ; Oxygen ; Production ; Respiration
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 7
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    Association for the Sciences of Limnology and Oceanography
    Publication Date: 2022-06-17
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Coogan, J., Rheuban, J., & Long, M. Evaluating benthic flux measurements from a gradient flux system. Limnology and Oceanography: Methods, 20, (2022): 222-232, https://doi.org/10.1002/lom3.10482.
    Description: Multiple methods exist to measure the benthic flux of dissolved oxygen (DO), but many are limited by short deployments and provide only a snapshot of the processes occurring at the sediment–water interface. The gradient flux (GF) method measures near bed gradients of DO and estimates the eddy diffusivity from existing turbulence closure methods to solve for the benthic flux. This study compares measurements at a seagrass, reef, and sand environment with measurements from two other methods, eddy covariance and benthic chambers, to highlight the strengths, weaknesses, and uncertainty of measurements being made. The results show three major areas of primary importance when using the GF method: (1) a sufficient DO gradient is critical to use this method and is limited by the DO sensor precision and gradient variability; (2) it is important to use similar methods when comparing across sites or time, as many of the methods showed good agreement but were often biased larger or smaller based on the method; and (3) in complex bottom types, estimates of the length scale and placement of the DO sensors can lead to large sources of error. Careful consideration of these potential errors is needed when using the GF method, but when properly addressed, this method showed high agreement with the other methods and may prove a useful tool for measuring long-term benthic fluxes of DO or other chemical sensors or constituents of interest that are incompatible with other methods.
    Description: This work was supported by NSF OCE grants 1657727 and 2023069.
    Repository Name: Woods Hole Open Access Server
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