Abstract.

A third or more of the fixed nitrogen lost from the oceans as N2 is removed by anaerobic microbial processes in open ocean oxygen minimum zones. These zones have expanded over the past decades, and further anthropogenically induced expansion could accelerate nitrogen loss. However, in the Bay of Bengal there has been no indication of nitrogen loss, although oxygen levels are below the detection level of conventional methods (1 to 2 μM). Here we quantify the abundance of microbial genes associated with N2 production, measure nitrogen transformations in incubations of sampled seawater with isotopically labelled nitrogen compounds and analyse geochemical signatures of these processes in the water column. We find that the Bay of Bengal supports denitrifier and anammox microbial populations, mediating low, but significant N loss.

Source: Nature Geoscience
Authors: L. A. Bristow et al.
DOI: 10.1038/ngeo2847

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The low oxygen conditions slow shrimp growth, leading to fewer and more expensive large shrimp.

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"Long treated as a bottomless resource pit, over-exploitation of the ocean, pollution and rising sea levels are having a catastrophic impact on life in the bay."

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