Primary productivity and nitrogen uptake in the eastern tropical Pacific Ocean

Margaret R Mulholland, Old Dominion University, Ocean and Earth Sciences, Norfolk, United States, Corday Selden, Cuernavaca, Mexico, Peter W Bernhardt, Old Dominion University, Department of Ocean and Earth Sciences, Norfolk, United States and Brittany Widner, Woods Hole Oceanographic Institution, Marine Chemistry & Geochemistry, Woods Hole, MA, United States
Abstract:
The eastern tropical Pacific Ocean harbors two of the world’s most expansive oxygen deficient zones. While these areas have recently been targeted as zones where dinitrogen fixation might be favored, subsequent observations suggest that rates are actually low there and restricted primarily to surface waters. The eastern tropical North and South Pacific Oceans have contrasting productivity regimes however, there are few reported rate measurements for primary productivity and dissolved inorganic nitrogen uptake to support this. Here we report rate measurements of primary productivity and dissolved inorganic nitrogen uptake in surface waters above and adjacent to these oxygen deficient waters. These rate measurements provide important observational data to ground-truth satellite chlorophyll observations and derived productivity estimates for the region.