Mechanisms of P* Reduction in the Eastern Tropical South Pacific

Mechanisms of P* Reduction in the Eastern Tropical South Pacific

Water masses influenced by oxygen minimum zones (OMZ) feature low inorganic nitrogen (N) to phosphorus (P) ratios. The surplus of P over N is thought to favor non-Redfield primary production by bloom-forming phytoplankton species. Additionally, excess phosphate (P) is thought to provide a niche for nitrogen fixing organisms. In order to assess the effect of low inorganic nutrient ratios on the ...

Aphotic N2 Fixation in the Eastern Tropical South Pacific Ocean

We examined rates of N2 fixation from the surface to 2000 m depth in the Eastern Tropical South Pacific (ETSP) during El Niño (2010) and La Niña (2011). Replicated vertical profiles performed under oxygen-free conditions show that N2 fixation takes place both in euphotic and aphotic waters, with rates reaching 155 to 509 µmol N m(-2) d(-1) in 2010 and 24±14 to 118±87 µmol N m(-2) d(-1) in 2011....

Dolphin Habitats in the Eastern Tropical Pacific

Research-ship surveys by the Southwest Fisheries Center provided information on the distributions of spotted, spinner, striped, and common dolphins in the eastern tropical Pacific. The main surveys were conducted from January to March during 1976,1977,1979, and 1980. 1\\'0 ships were used per survey, and together they overlapped most areas in the eastern Pacific where dolphins and yellowfin tun...

What prevents nitrogen depletion in the OMZ of the Eastern Tropical South Pacific?

What prevents nitrogen depletion in the oxygen minimum zone of the eastern tropical South Pacific?

Local coupling between nitrogen fixation and denitrification in current biogeochemical models could result in runaway feedback in open-ocean oxygen minimum zones (OMZs), eventually stripping OMZ waters of all fixed nitrogen. This feedback does not seem to operate at full strength in the ocean, as nitrate does not generally become depleted in open-ocean OMZs. To explore in detail the possible me...