Niche occupation of anammox bacteria in the eastern tropical North Pacific
Abstract
[Author's abstract] Nitrogen is a limiting nutrient controlling oceanic primary production and important to the global carbon cycle. Consequently the nitrogen cycle is important to understanding how the oceans will react to climate change in respect to the biological pump. Oxygen Minimum Zones (OMZs) are areas of the ocean characterized by low oxygen levels and areas with high rates of nitrogen removal. OMZs are expected to grow in the future, possibly increasing nitrogen removal from the ocean (Paulmier and Ruiz-Pino. 2008). The OMZ in the Eastern Tropical North Pacific (ETNP) is the largest OMZ in the world, running from 0°-25° N with a core ranging in depths from 280m to 850m (Paulmier and Ruiz-Pino. 2008). Anaerobic ammonium oxidizing (anammox) bacteria are of particular interest in the OMZs because of their ability to autotrophically convert fixed nitrogen in the form of ammonia (NH4+) and nitrite (NO2-) into N2 gas, which is a state unavailable to most biology. Anammox bacteria were found on 0.2ìm and 30ìm filters, suggesting the ability of anammox bacteria to live within anoxic microniches of particles and also as free floating bacteria in the ETNP.