National Institute of Oceanography, India

About: National Institute of Oceanography, India is a facility organization based out in Panjim, Goa, India. It is known for research contribution in the topics: Monsoon & Population. The organization has 4713 authors who have published 6927 publications receiving 174272 citations.

Offshore Frontal Part of the Makran Accretionary Prism: The Chamak Survey (Pakistan)

Abstract: The Makran accretionary prism developed in the north-western part of the Indian Ocean as a consequence of the subduction of the Arabian Sea since Late Cretaceous times. It extends from southern Iran to the Baluchistan region of Pakistan where it joins the Chaman-Ornach-Nal left-lateral strike-slip fault systems to the north and the Owen Fracture Zone-Murray Ridge transtensional (right-lateral) system to the south in a complex triple junction near the city of Karachi. In September to October of 2004, we surveyed most of the accretionary complex off Pakistan with R/V Marion Dufresne. We achieved a nearly continuous bathymetric mapping of the prism and the subduction trench from 62°30′E to the triple junction near 62°30′E together with nearly 1000 km of seismic reflection (13 lines) and we took 18 piston cores in different geological settings. One of the main results is that the frontal part of the Makran accretionary prism is less two-dimensional than previously expected. We interpret the along-strike tectonic variation as a consequence of lateral variations in sediment deposition as well as a consequence of the under-thrusting of a series of basement highs and finally of the vicinity to the triple junction.

High new production in the Bay of Bengal: Possible causes and implications

Abstract: [1] We report the first measurements of new production (15N tracer technique), the component of primary production that sustains on extraneous nutrient inputs to the euphotic zone, in the Bay of Bengal. Experiments done in two different seasons consistently show high new production (averaging around 4 mmol N m−2 d−1 during post monsoon and 5.4 mmol N m−2 d−1 during pre monsoon), validating the earlier conjecture of high new production, based on pCO2 measurements, in the Bay. Averaged over annual time scales, higher new production could cause higher rate of removal of organic carbon. This could also be one of the reasons for comparable organic carbon fluxes observed in the sediment traps of the Bay of Bengal and the eastern Arabian Sea. Thus, oceanic regions like Bay of Bengal may play a more significant role in removing the excess CO2 from the atmosphere than hitherto believed.

Tides in the Mandovi and Zuari estuaries, Goa, west coast of India

Abstract: Mandovi and Zuari are two estuaries located in Goa, west coast of India. Variation of water level in the estuaries was monitored for a month at 13 locations using tide-poles during March–April 2003. Analysis of this data has provided for the first time, characteristics of how tidal constituents vary in the narrow and shallow estuaries, typical of those found along the west coast of India. At a distance of 45 km from the mouth the tidal range increased in both estuaries by approximately 20%. The tidal range at the upstream end of the two channels at the stations dropped sharply because of the increase in elevation of the channels.

Contribution of mono and polysaccharides to heterotrophic N2 fixation at the eastern Mediterranean coastline.

Abstract: N2 fixation should be a critical process in the nitrogen-poor surface water of the eastern Mediterranean Sea. Despite favorable conditions, diazotroph abundance and N2 fixation rates remains low for reasons yet explained. The main goal of this study was to investigate the limiting nutrients for diazotrophy in this oligotrophic environment. Hence, we conducted dedicated bottle-microcosms with eastern Mediterranean Sea water that were supplemented with mono and polysaccharides as well as inorganic nitrogen and phosphorous. Our results indicate that the diazotrophic community expressing nifH was primarily represented by heterotrophic Proteobacteria. N2 fixation and heterotrophic bacterial activity increased up-to tenfold following two days of dark incubations, once seawater was supplemented with organic carbon substrate in the form of glucose (monosaccharides) or gum-xanthan (polysaccharide surrogate). Furthermore, our results point that carbon-rich polysaccharides, such as transparent exopolymer particles, enhance heterotrophic N2 fixation, by forming microenvironments of intense metabolic activity, high carbon: nitrogen ratio, and possibly low O2 levels. The conclusions of this study indicate that diazotrophs in the eastern Mediterranean coast are primarily limited by organic carbon substrates, as possibly in many other marine regions.