Signorini Sergio R.

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Signorini
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Sergio R.
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  • Article
    Understanding, characterizing, and communicating responses to ocean acidification : challenges and uncertainties
    (The Oceanography Society, 2015-06) Busch, D. Shallin ; O’Donnell, Michael J. ; Hauri, Claudine ; Mach, Katharine J. ; Poach, Matthew ; Doney, Scott C. ; Signorini, Sergio R.
    Over the past decade, ocean acidification (OA) has emerged as a major concern in ocean science. The field of OA is based on certainties—uptake of carbon dioxide into the global ocean alters its carbon chemistry, and many marine organisms, especially calcifiers, are sensitive to this change. However, the field must accommodate uncertainties about the seriousness of these impacts as it synthesizes and draws conclusions from multiple disciplines. There is pressure from stakeholders to expeditiously inform society about the extent to which OA will impact marine ecosystems and the people who depend on them. Ultimately, decisions about actions related to OA require evaluating risks about the likelihood and magnitude of these impacts. As the scientific literature accumulates, some of the uncertainty related to single-species sensitivity to OA is diminishing. Difficulties remain in scaling laboratory results to species and ecosystem responses in nature, though modeling exercises provide useful insight. As recognition of OA grows, scientists’ ability to communicate the certainties and uncertainties of our knowledge on OA is crucial for interaction with decision makers. In this regard, there are a number of valuable practices that can be drawn from other fields, especially the global climate change community. A generally accepted set of best practices that scientists follow in their discussions of uncertainty would be helpful for the community engaged in ocean acidification.
  • Article
    Surface ocean pCO2 seasonality and sea-air CO2 flux estimates for the North American east coast
    (John Wiley & Sons, 2013-10-16) Signorini, Sergio R. ; Mannino, Antonio ; Najjar, Raymond G. ; Friedrichs, Marjorie A. M. ; Cai, Wei-Jun ; Salisbury, Joseph E. ; Wang, Zhaohui Aleck ; Thomas, Helmuth ; Shadwick, Elizabeth H.
    Underway and in situ observations of surface ocean pCO2, combined with satellite data, were used to develop pCO2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO2 and sea-air CO2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NS+GB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO2. Estimates of the sea-air CO2 flux were derived from the available pCO2 data, as well as from the pCO2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GB+NS, MAB, and SAB regions are net sinks of atmospheric CO2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO2 by eastern North American continental shelf waters is found to be between −3.4 and −5.4 Tg C yr−1 (areal average of −0.7 to −1.0 mol CO2 m−2 yr−1) over the period 2003–2010.
  • Article
    Carbon budget of tidal wetlands, estuaries, and shelf waters of eastern North America
    (John Wiley & Sons, 2018-04-04) Najjar, Raymond G. ; Herrmann, Maria ; Alexander, Richard ; Boyer, Elizabeth W. ; Burdige, David J. ; Butman, David ; Cai, Wei-Jun ; Canuel, Elizabeth A. ; Chen, Robert F. ; Friedrichs, Marjorie A. M. ; Feagin, Russell A. ; Griffith, Peter C. ; Hinson, Audra L. ; Holmquist, James R. ; Hu, Xinping ; Kemp, William M. ; Kroeger, Kevin D. ; Mannino, Antonio ; McCallister, S. Leigh ; McGillis, Wade R. ; Mulholland, Margaret R. ; Pilskaln, Cynthia H. ; Salisbury, Joseph E. ; Signorini, Sergio R. ; St-Laurent, Pierre ; Tian, Hanqin ; Tzortziou, Maria ; Vlahos, Penny ; Wang, Zhaohui Aleck ; Zimmerman, Richard C.
    Carbon cycling in the coastal zone affects global carbon budgets and is critical for understanding the urgent issues of hypoxia, acidification, and tidal wetland loss. However, there are no regional carbon budgets spanning the three main ecosystems in coastal waters: tidal wetlands, estuaries, and shelf waters. Here we construct such a budget for eastern North America using historical data, empirical models, remote sensing algorithms, and process‐based models. Considering the net fluxes of total carbon at the domain boundaries, 59 ± 12% (± 2 standard errors) of the carbon entering is from rivers and 41 ± 12% is from the atmosphere, while 80 ± 9% of the carbon leaving is exported to the open ocean and 20 ± 9% is buried. Net lateral carbon transfers between the three main ecosystem types are comparable to fluxes at the domain boundaries. Each ecosystem type contributes substantially to exchange with the atmosphere, with CO2 uptake split evenly between tidal wetlands and shelf waters, and estuarine CO2 outgassing offsetting half of the uptake. Similarly, burial is about equal in tidal wetlands and shelf waters, while estuaries play a smaller but still substantial role. The importance of tidal wetlands and estuaries in the overall budget is remarkable given that they, respectively, make up only 2.4 and 8.9% of the study domain area. This study shows that coastal carbon budgets should explicitly include tidal wetlands, estuaries, shelf waters, and the linkages between them; ignoring any of them may produce a biased picture of coastal carbon cycling.
  • Article
    Ocean and coastal acidification off New England and Nova Scotia
    (The Oceanography Society, 2015-06) Gledhill, Dwight K. ; White, Meredith M. ; Salisbury, Joseph E. ; Thomas, Helmuth ; Mlsna, Ivy ; Liebman, Matthew ; Mook, Bill ; Grear, Jason S. ; Candelmo, Allison C. ; Chambers, R. Christopher ; Gobler, Christopher J. ; Hunt, Christopher W. ; King, Andrew L. ; Price, Nichole N. ; Signorini, Sergio R. ; Stancioff, Esperanza ; Stymiest, Cassie ; Wahle, Richard A. ; Waller, Jesica D. ; Rebuck, Nathan D. ; Wang, Zhaohui Aleck ; Capson, Todd L. ; Morrison, J. Ruairidh ; Cooley, Sarah R. ; Doney, Scott C.
    New England coastal and adjacent Nova Scotia shelf waters have a reduced buffering capacity because of significant freshwater input, making the region’s waters potentially more vulnerable to coastal acidification. Nutrient loading and heavy precipitation events further acidify the region’s poorly buffered coastal waters. Despite the apparent vulnerability of these waters, and fisheries’ and mariculture’s significant dependence on calcifying species, the community lacks the ability to confidently predict how the region’s ecosystems will respond to continued ocean and coastal acidification. Here, we discuss ocean and coastal acidification processes specific to New England coastal and Nova Scotia shelf waters and review current understanding of the biological consequences most relevant to the region. We also identify key research and monitoring needs to be addressed and highlight existing capacities that should be leveraged to advance a regional understanding of ocean and coastal acidification.