Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014)
© 2016. American Geophysical Union. All Rights Reserved. In this study, we examined the interannual variability of net community production (NCP) in the Western Antarctic Peninsula (WAP) using in situ O2/Ar-NCP estimates (2008–2014) and satellite data (SeaWiFS and MODIS-Aqua) from 1997 to 2014. We found that NCP generally first peaks offshore and follows sea-ice retreat from offshore to inshore. Annually integrated NCP (ANCP) displays an onshore-to-offshore gradient, with coastal and shelf regions up to 8 times more productive than offshore regions. We examined potential drivers of interannual variability in the ANCP using an Empirical Orthogonal Function (EOF) analysis. The EOF's first mode explains ∼50% of the variance, with high interannual variability observed seaward of the shelf break. The first principal component is significantly correlated with the day of sea-ice retreat (R = −0.58, p < 0.05), as well as the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) climate indices in austral spring. Although the most obvious pathway by which the day of sea-ice retreat influences NCP is by controlling light availability early in the growing season, we found that the effect of day of sea-ice retreat on NCP persists throughout the growing season, suggesting that additional controls, such as iron availability, are preconditioned or correlated to the day of sea-ice retreat.
Li, Z; Cassar, N; Huang, K; Ducklow, H; Schofield, O
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