Global declines in oceanic nitrification rates as a consequence of ocean acidification
- 20 December 2010
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 108 (1), 208-213
- https://doi.org/10.1073/pnas.1011053108
Abstract
Ocean acidification produced by dissolution of anthropogenic carbon dioxide (CO2) emissions in seawater has profound consequences for marine ecology and biogeochemistry. The oceans have absorbed one-third of CO2 emissions over the past two centuries, altering ocean chemistry, reducing seawater pH, and affecting marine animals and phytoplankton in multiple ways. Microbially mediated ocean biogeochemical processes will be pivotal in determining how the earth system responds to global environmental change; however, how they may be altered by ocean acidification is largely unknown. We show here that microbial nitrification rates decreased in every instance when pH was experimentally reduced (by 0.05–0.14) at multiple locations in the Atlantic and Pacific Oceans. Nitrification is a central process in the nitrogen cycle that produces both the greenhouse gas nitrous oxide and oxidized forms of nitrogen used by phytoplankton and other microorganisms in the sea; at the Bermuda Atlantic Time Series and Hawaii Ocean Time-series sites, experimental acidification decreased ammonia oxidation rates by 38% and 36%. Ammonia oxidation rates were also strongly and inversely correlated with pH along a gradient produced in the oligotrophic Sargasso Sea (r2 = 0.87, P < 0.05). Across all experiments, rates declined by 8–38% in low pH treatments, and the greatest absolute decrease occurred where rates were highest off the California coast. Collectively our results suggest that ocean acidification could reduce nitrification rates by 3–44% within the next few decades, affecting oceanic nitrous oxide production, reducing supplies of oxidized nitrogen in the upper layers of the ocean, and fundamentally altering nitrogen cycling in the sea.Keywords
This publication has 45 references indexed in Scilit:
- Will ocean acidification affect marine microbes?The ISME Journal, 2010
- Nitrosopumilus maritimus genome reveals unique mechanisms for nitrification and autotrophy in globally distributed marine crenarchaeaProceedings of the National Academy of Sciences of the United States of America, 2010
- TESTING THE EFFECTS OF OCEAN ACIDIFICATION ON ALGAL METABOLISM: CONSIDERATIONS FOR EXPERIMENTAL DESIGNS1Journal of Phycology, 2009
- Nutrient Cycles and Marine Microbes in a CO2-Enriched OceanOceanography, 2009
- Physical and biogeochemical modulation of ocean acidification in the central North PacificProceedings of the National Academy of Sciences of the United States of America, 2009
- Dynamic patterns and ecological impacts of declining ocean pH in a high-resolution multi-year datasetProceedings of the National Academy of Sciences of the United States of America, 2008
- Impacts of ocean acidification on marine fauna and ecosystem processesICES Journal of Marine Science, 2008
- Ammonium regeneration and nitrification rates in the oligotrophic Atlantic Ocean: Implications for new production estimatesLimnology and Oceanography, 2008
- Genomic analysis of the uncultivated marine crenarchaeote Cenarchaeum symbiosumProceedings of the National Academy of Sciences of the United States of America, 2006
- The Oceanic Sink for Anthropogenic CO 2Science, 2004