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.

Benthic fluxes in a tropical Estuary and their role in the ecosystem

Abstract: In-situ measurements of benthic fluxes of oxygen and nutrients were made in the subtidal region of the Mandovi estuary during premonsoon and monsoon seasons to understand the role of sediment–water exchange processes in the estuarine ecosystem. The Mandovi estuary is a shallow, highly dynamic, macrotidal estuary which experiences marine condition in the premonsoon season and nearly fresh water condition in the monsoon season. The benthic flux of nutrients exhibited strong seasonality, being higher in the premonsoon compared to the monsoon season which explains the higher ecosystem productivity in the dry season in spite of negligible riverine nutrient input. NH 4 + was the major form of released N comprising 70–100% of DIN flux. The benthic respiration rate varied from −98.91 to −35.13 mmol m −2 d −1 , NH 4 + flux from 5.15 to 0.836 mmol m −2 d −1 , NO 3 − + NO 2 − from 0.06 to −1.06 mmol m −2 d −1 , DIP from 0.12 to 0.23 mmol m −2 d −1 and SiO 4 4− from 5.78 to 0.41 mmol m −2 d −1 between premonsoon to monsoon period. The estuarine sediment acted as a net source of DIN in the premonsoon season, but changed to a net sink in the monsoon season. Variation in salinity seemed to control NH 4 + flux considerably. Macrofaunal activities, especially bioturbation, enhanced the fluxes 2–25 times. The estuarine sediment was observed to be a huge reservoir of NH 4 + , PO 4 3− and SiO 4 4− and acted as a net sink of combined N because of the high rate of benthic denitrification as it could remove 22% of riverine DIN influx thereby protecting the eco system from eutrophication and consequent degradation. The estuarine sediment was responsible for ∼30–50% of the total community respiration in the estuary. The benthic supply of DIN, PO 4 3− and SiO 4 4− can potentially meet 49%, 25% and 55% of algal N, P and Si demand, respectively, in the estuary. Based on these observations we hypothesize that it is mainly benthic NH 4 + efflux that sustains high estuarine productivity in the NO 3 − depleted dry season.

Comparison of wind data from QuikSCAT and buoys in the Indian Ocean

Abstract: The performance of QuikSCAT-derived wind vectors is evaluated using in-situ data from moored buoys over the Indian Ocean. The results show that the mean differences for wind speed and wind direction are 0.37 ms-1 and 5.8°, root mean square deviations are 1.57 ms-1 and 44.1° and corresponding coefficients of correlation are 0.87 and 0.75, respectively. The matching between in-situ and satellite estimates seems to be better in the North Indian Ocean than in the Equatorial Indian Ocean. The effects of sea surface temperature and air-sea temperature difference on wind residuals were also investigated. In general, QuikSCAT is found to overestimate the winds. It is speculated that low wind speed during rain-free conditions and high wind speed, normally associated with rain, may be the reason for the less accurate estimation of the wind vector from QuikSCAT over the Indian Ocean.

Trace metal content in deep-water sharks from the eastern Mediterranean Sea

Abstract: Trace metals were analyzed in the muscle and other organs from several species of deep-water sharks (particularly Centrophorus granulosus and Galeus melastomus) from 1280 to 1500 m depth in the eastern Mediterranean between 1985 and 1991. As has been shown with other pelagic fish, there was a significant correlation between specimen size and the mercury concentration in the muscle as well as in the liver and kidneys. For a given size, the level of mercury in sharks from the eastern Mediterranean was considerably higher compared with the same species caught off the west coast of Italy. There was no significant correlation between the concentrations of Cd, Cu, Zn and Fe in the muscle (or other organs) and body size. The overall trace metal content was considerably higher in the specimens from the eastern Mediterranean compared with the same species from the N. E. Atlantic. It is suggested that these higher-than-expected trace metal levels might be due to a relatively high trace metal content in the waters of the region or to the unusual physiology of these fish, possibly related to the extreme oligotrophic conditions in the area.

Sediment redistribution during simulated benthic disturbance and its implications on deep seabed mining

Abstract: A benthic disturbance experiment was conducted in the Central Indian Basin to evaluate the possible effects of sediment redistribution on marine ecosystem during deep-sea mining. The analyses of disturbance features on the seafloor and particle resettlement indicate that the most intense impact is created within the experiment site, and some of the resuspended sediments that remain in the near-bottom water after the disturbance are transported away from the site, changing the physico-chemical conditions in the area. Resedimentation is observed on either side of the disturbance zone, with an increase in suspended particles by 300% (from 49 to 150 mg/m 2 /day) during the disturbance and a reduction by 33% (to 95 mg/m 2 /day) immediately after the experiment. Higher collection of particles as well as an increase in organic carbon in seafloor sediments S–SW of the disturbance zone indicates directional migration of suspended material and redeposition in the adjacent areas. The implications of increase in turbidity and sedimentation rates in the near bottom water column due to sediment re-suspension, as well as lateral migration of sediment, on the benthic ecosystem have been discussed. These parameters provide important inputs in ascertaining long-term effects of deep-sea mining.