Wednesday, 26 July 2017
A research to investigate oxygen depletion in Arabian Sea

A tri-nation ocean research to investigate oxygen depletion in the Arabian Sea will kick off next week with the arrival of an Indian Ocean research vessel, Sagar Kanya here, Manjeev Singh Puri, minister, Indian Embassy informed the media, yesterday.

Oman, India and the USA are collaborating on the Ocean Research Project focusing on the Arabian Sea.

It is in this context that Sagar Kanya will be arriving here next Sunday. The research vessel will be here till next Tuesday, cruising in the Omani waters, carrying out research before returning to India, Manjeev Singh said.

In India the project is being coordinated by the National Institute of Oceanography. Sagar Kanya is operated by the National Centre for Ocean and Antarctic Research of India.

In Oman the Ministry of Agriculture and Fisheries, the Marine Science and Fisheries Centre and Sultan Qaboos University are the collaborating parties. The American scientists participating in the cruise are from Princeton University and Woods Hole Oceanographic Institute. The Arabian Sea is one of the most unusual and interesting parts of the oceans, largely because of its geographical setting — it is surrounded by land masses from three sides. The phenomenon of monsoons — the seasonally reversing winds and surface currents — is unique to this part of the world.

"Associated with this circulation, there occurs extensive fertilisation of surface waters through a process called upwelling which is most intense along the Omani coast.

"This process involves offshore drift of surface waters and their replacement by deep waters which are rich in nutrients such as nitrate and phosphate. This process makes the Arabian Sea in general and the Omani coast in particular very productive. While this sustains rich fisheries, particular along the Omani coast, there are also some deleterious effects of such fertilisation. The most important of these is oxygen depletion in subsurface waters which is caused by the decay of the copious amounts of organic matter produced by plankton. The oxygen poor water can sometimes come close to the surface resulting in fish kills such the one that occurred in the Ras Al Hadd region two weeks ago.

"The oxygen deficiency also causes extremely vigorous production of nitrous oxide (laughing gas) which is an important greenhouse gas that not only contributes to global warming but also to the depletion of ozone in the stratosphere. The Arabian Sea is a globally important producer of this gas," the researchers said.

The present expedition involves joint research by the Omani, Indian and US scientists to investigate aspects of oxygen deficiency in the Arabian Sea. As the oxygen depletion is caused by the organic carbon production and decay, we are measuring rates of carbon production by phytoplankton and its respiration.

"We are focusing on interactions between certain trace metals such as iron and copper with the nitrogen cycle. This is because the availability of these metals in suitable forms regulates the activity and functions of ceratin key enzymes. We are largely concerned with enzymes that affect nitrous oxide cycling, namely nitrite reductase (NIR), one with copper (NirK) in its active centre and the second, which requires iron (NirS). We are investigating the community structure of the bacterial assemblages in the Oxygen Minimum Zone (OMZ) in order to evaluate the possible relationship between the diversity and biogeochemistry and also the distribution of the copper type organism versus iron type in relation to the speciation of copper and iron. This study would involve state of the art molecular biological techniques to investigate relative gene abundance and expression and eventually that would be compared to the denitrification rates in this region and the trace metal speciation," the researchers added.


General contact:   Prof. Sergey Piontkovski
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