Anoxic conditions could be behind reduction in fish population along Goan coast: NIO
Stating that the gradual reduction in fish population along the Goan coast could not be attributed to the December 2004 tsunami due to the lack of scientific evidence, the director of National Institute of Oceanography, Dr S W A Naqvi on Wednesday said the phenomenon is certainly related to hydrography,
and one of the reasons for the same could be creation of anoxic conditions in these waters, especially after the monsoon season.
“This condition is annually intensifying and driving away the fishes from the Goan coast,” he added.
The annual marine fish catch in Goa from 2001 to 2011 had reached its peak in the year 2005, with the fish haul that year standing at 1,03,087 tonne. Subsequently, the fish haul was reduced the following years by nearly 27 per cent, and stabilised between 85,000 and 90,000 tonne. The department of fisheries had ascribed this drop to tsunami, stating that the related changes in the basin of the Indian Ocean, has affected the aquatic life.
Dr Naqvi said that any effect of the tsunami on the aquatic life would be short-timed, and there must be other reasons for drop in the quantity of fish caught along the Goan coast. “The distribution of oxygen to the water is an important factor for presence of fish in that water,” he observed, pointing out that anoxic conditions may be responsible for less fish population along Goan waters.
Anoxia means a total depletion in the level of oxygen, which is an extreme form of hypoxia or ‘low oxygen’. The anoxic waters are areas of seawater, freshwater or groundwater, which are depleted of dissolved oxygen. This condition is generally found in areas that have restricted water exchange. The anoxic conditions will occur if the rate of oxidation of organic matter by bacteria is greater than the supply of dissolved oxygen. These conditions result from several factors such as stagnation conditions, density stratification, inputs of organic material, and strong thermoclines.
Dr Naqvi was addressing a press conference on the eve of a two-day workshop on ‘Marine geosciences research in India: Current status and future directions’, to be inaugurated at the NIO Cardium, on February 21 in commemoration of the golden jubilee of Indian Geophysical Union, one of the oldest and reputed geosciences organisation of the country.
The workshop is aimed towards enabling understanding amongst students about some of the fundamental processes governing the formation of several marine minerals as well as to understand the oceanic processes and past climate change. The president of the Indian Geophysical Union, Dr V P Dimri and the convenor of the workshop, Dr Rajiv Nigam were also present for the briefing.
The member of the National Disaster Management Authority, Dr Harsh Gupta, who will inaugurate the workshop, told the pressmen that following the December 2004 tsunami, the Indian government acted fast and within next 30 months, set up the state-of-the-art Tsunami Warning System.
“The best part of this system is that it gives no false alarms,” he added, informing that the department of ocean development has installed ocean bottom pressure recorders close to two zones – from Java Sumatra to Andaman Nicobar and at the Makaran coast in the Arabian Sea – in the Indian Ocean that are most likely to generate earthquakes.
Dr Gupta also said that India is in the forefront in ocean sciences and its work in the Arctic region as well as in the Antarctica falls in the sphere of ocean sciences. “In fact, around 150 microbes have been discovered at Antarctica, till date, with more than half of them being discovered by Indian scientists,” he announced, stating that unfortunately, 70 per cent of the requirements for such works as carried out by our scientists, are imported.
The member of the National Disaster Management Authority also informed that Indian marine scientists have done lot of work on gas hydrates found on the seafloor, in ocean sediments.
“Gas hydrates form no more a futuristic resource and we should exploit the same,” he concluded.
Dr Dimri said that a series of conferences have been organised around the country to celebrate the golden jubilee of Indian Geophysical Union.
The two-day workshop at the NIO is expected to have participation of more than 200 participants, including masters’ students, research scholars and early career scientists from earth science departments all over the country. [NT]