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GCE III - Key Finding in 2014

    Large-scale climate drivers are linked to river discharge

    Freshwater delivery is an important factor determining estuarine characteristics and may be influenced by large-scale climate oscillations. J. Sheldon and Burd (2014) investigated the effects of seven climate signals on the precipitation and river discharge patterns of the Altamaha River watershed, which provides most of the freshwater to the GCE site. They found statistical linkages between three climate signals (the Bermuda High, the ENSO cycle, and the Atlantic Multidecadal Oscillation), precipitation and river discharge. Additional analyses revealed that the complex, seasonally alternating pattern of climate signals that affects precipitation and river discharge in the Altamaha River watershed also extends to the neighboring Ogeechee, Satilla, and St. Marys watersheds (Fig 1). Thus, changes in large-scale climate signals as well as the interplay among them have the potential to affect the amount and seasonality of freshwater entering these estuaries, which in turn will affect downstream ecosystems. This connection was borne out by Wieski and Pennings (2014) who showed that river discharge was the most important driver of S. alterniflora net primary production at almost all GCE sites, with high primary production in years following high river discharge. The next step will be to assess relationships between climate signals, salinity, and survey data for shrimp and crabs.

    2014_Accomplishments_Fig1

    Fig. 1 Monthwise correlations between climate signals and river discharge into 4 Georgia riverine estuaries. In each square, the left triangle is the Southern Oscillation Index (ENSO), the top is the Bermuda High Index, and the bottom is the Atlantic Multidecadal Oscillation. The intensity of the triangle color denotes the strength of the correlation (weak: 0.1 < |r| < 0.3, moderate: 0.3 < |r| < 0.5, strong: |r| > 0.5), and negative correlations are indicated by a dot within the triangle. From Sheldon and Alber (2013) and Sheldon and Burd (2014).



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This material is based upon work supported by the National Science Foundation under grants OCE-9982133, OCE-0620959, OCE-1237140 and OCE-1832178. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.