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RV Sindhu Sankalp completes hundred cruises
Research Vessels are floating laboratories and are crucial for the development of ocean sciences in any country. Research Vessel, RV Sindhu Sankalp, owned and operated by the CSIR-National Institute of Oceanography, completed 100 oceanographic cruises successfully, in the seas around India, including the Arabian Sea, Bay of Bengal and the Andaman Sea. Scientists of the CSIR-NIO acquired invaluable data and samples, to understand the ocean processes and map seafloor and water column variables.
Dr. P. S. Rao, Head of Research Vessels Management, CSIR-NIO and Leader of the 100th cruise, informed that the 56.3 meters long RV Sindhu Sankalp, originally built as a Training Vessel by the Japanese Government, was acquired by the CSIR-NIO in 2008 and has been modified in 2009 as an oceanographic research vessel by creating laboratories and fitting with several scientific equipments such as CTD system, multibeam bathymetric system, echosounder and sub-bottom profiler. Besides, the vessel has deck facilities such as winches, cranes and ‘A’ frame to support deployment and retrieval of instrumented moorings, towing of sensors and sampling of water column and seafloor.
Dr. Prasanna Kumar, Acting Director, says that the seafloor information from high resolution mapping and sampling with RV Sindhu Sankalp helped in identifying suitable areas for offshore developments and mineral prospecting including petroleum hydrocarbons. Experiments were conducted to understand the importance of sedimentary processes in the burial of organic matter and sequestering of atmospheric carbon dioxide in marine sediments which play a significant role in global carbon budget. The vessel has been extensively used to deploy and recover instrumented mooring which record continuous data of various water column parameters, such as temperature, salinity, currents, nutrients etc., which are essential to understand ocean environment and associated ecosystem, including fisheries. Besides, RV Sindhu Sankalp contributed significantly for industrial development, especially in the Krishna-Godavari Basin by conducting seabed geophysical and environmental surveys. Recently, RV Sindhu Sankalp completed environmental survey for evaluating ecological status in the coastal waters off Mumbai, around the sunken ship MV Rak Carrier.
For the 100th cruise, RV Sindhu Sankalp sailed from Visakhapatnam Port on 2nd March 2017 with an objective to map mapped part of Eastern Continental Margin of India, especially in the region off Visakhapatnam with multi-beam sonar system to unravel the seafloor morphology. Dr. P.S. Rao, Leader of the present cruise, observed that this cruise is significant in many ways not only because it is 100th cruise, a landmark in the history of any research vessel, but also for its scientific achievements. Way back in 1963, Prof. E.C. LaFond of US Navy Electronics Laboratory, who was carrying out marine studies at Andhra University at that time, noted the presence of three canyons with the help of an echogram (record of seafloor depth profile along a cruise track), collected onboard American vessel Anton Bruun and named them as (i) Andhra Canyon, after the Andhra University; (ii) Mahadevan Canyon in the name of the Late Prof. C. Mahadevan, former Principal and founder of Geology Department at Andhra University; and (iii) Krishna Canyon, after the Late Vice-Chancellor of Andhra University, who was responsible for start of Marine Sciences at Andhra University . Since then no serious attempts were made to map these canyons. During this cruise, we could map the canyons in great detail and found that these three canyons join at about 1000 m to form major canyon system, which we may tentatively call AMK (Andhra-Mahadevan-Krishna) Canyon System. Further, Prof. La Fond also noted the presence of three small “V” shaped canyons (unnamed) south of Andhra Canyon. Our efforts revealed that these canyons also join in deeper waters to form another major canyon system, as large as the ABK Canyon System. We intend to call this canyon system as “Visakha Canyon”, after the famous Port City Visakhapatnam. During this cruise, we have also discovered a new canyon north of Krishna Canyon, which we wish to name Sankalp Canyon in recognition of 100th cruise of RV Sindhu Sankalp, following due procedure.
Although several theories were proposed to explain the origin of canyons, there is a general agreement that turbidity currents play a major role in the formation of canyons. Yet again, there are several factors which may cause turbidity currents. Detailed processing and analysis of data collected may provide evidence of the factors responsible for the formation of the canyons, off Visakhapatnam. However, from the preliminary observations of the multibeam bathymetry, it appears that sediment failure at the shelf break acted as triggering mechanism.
Study of submarine canyons is important for several reasons. Submarine canyons are steep walled valleys that incise continental margins and are major pathways for the transport of sediment (and associated pollutants and organic carbon) from land to the deep ocean. Sediments thus transported and deposited form lobes, which are considered conducive for petroleum hydrocarbon accumulation. Canyons may cause slope failures damaging seafloor cables, pipelines and deep offshore installations. Because of their peculiar topography, currents, upwelling, nutrient availability and episodic flushing, the water column conditions in the canyons are different from the surrounding regions and support diverse ecosystem.
The CSIR-NIO developed long-term plan to study the canyons of Eastern Continental Margin of India to highlight key geological and sedimentary features and understand the processes that are responsible for origin and evolution of the canyons. An integrated approach, combining geological, oceanographic and biological and ecological observations, aided by time-series insitu measurements is required on priority. The results are expected to have potential implications for three main areas : 1) petroleum hydrocarbons — predicting variations in vertical connectivity and lateral extent of sandy deposits in deep-water channel systems will lead to a better understanding of heterogeneity within sedimentary strata, 2) geohazards—predicting the catastrophic effects and flow processes of large gravity flows and slope instabilities will help to reduce potential damage to continental margin infrastructures, and 3) benthic ecosystems- as there is great variability in environmental characteristics that determine the diversity and the ecology of their fauna both within individual canyon systems and between different canyons.
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