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Amal Jayakumar - About Me

My research interest is centered on microbially mediated nitrogen transformations in oceanic oxygen minimum zones. Although low oxygen conditions below the mixed layer is a common feature in most of the world oceans, only in ~2% of the ocean (by volume) the dissolved oxygen concentration gets low enough to induce anaerobic metabolism. Major regions of the world oceans, where such Oceanic Oxygen Minimum Zones (OMZ) persists are the Eastern Tropical North and South Pacific and the Arabian Sea.

For the last decade or so I have been involved in research, investigating the microbial communities that are responsible for the nitrogen transformations in OMZs, by targeting their signature genes to link it to the rates of geochemical transformations in these environments.   

One of the key questions that have been the focus my research is to investigate the microbes involved in nitrogen removal process and relate it to the rate of the removal process. For this, I have been studying the diversity and community dynamics of microbes involved in the classical denitrification pathway and the more recently discovered anammox pathway.

Results from these studies show that denitrifying bacteria are diverse in the OMZ and undergo classical bloom dynamics.   When there is a supply of high organic carbon to these OMZ environments, the denitrifying community goes from a high diversity low abundance community to high abundance low diverse community, resulting in the bloom of a dominant denitrifying organism. This bloom is associated with high nitrogen removal from these systems. Our studies also show that the dominant pathway for nitrogen removal in the Arabian Sea is denitrification and this happens immediately following seasons of high primary productivity. The anammox process is also expected to occur, as the bacteria that are responsible to carry out this process is also present in this OMZ. The anammox process is less important during times of high organic carbon input and is carried out by a low diversity, less abundant group of bacteria. The abundance and distributions of denitrifiers and anammox bacteria from the ETSP region are similar to that of the Arabian Sea, however, data published so far from ETSP suggests the dominance of the anammox pathway in nitrogen removal. Whether denitrification would become dominant during seasons of high productivity in the ETSP needs to be investigated in future.