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.

Metabolism of DMSP, DMS and DMSO by the cultivable bacterial community associated with the DMSP-producing dinoflagellate Scrippsiella trochoidea

Abstract: Bacterial species associated with the dimethylsulfoniopropionate (DMSP)-producing phytoplankton Scrippsiella trochoidea were cultured and identified, with the aim of establishing their ability to metabolise DMSP, dimethylsulfide (DMS) and dimethylsulfoxide (DMSO). Results demonstrate that of the cultivable bacteria only α-Proteobacteria were capable of producing DMS from DMSP. The concentration of DMSP was shown to affect the amount of DMS produced. Lower DMSP concentrations (1.5 μmol dm−3) were completely assimilated, whereas higher concentrations (10 μmol dm−3) resulted in increasing amounts of DMS being produced. By contrast to the restricted set of bacteria that metabolised DMSP, ~ 70% of the bacterial isolates were able to ‘consume’ DMS. However, 98-100% of the DMS removed was accounted for as DMSO. Notably, a number of these bacteria would only oxidise DMS in the presence of glucose, including members of the γ-Proteobacteria and Bacteroidetes. The observations from this study, coupled with published field data, identify DMS oxidation to DMSO as a major transformation pathway for DMS, and we speculate that the fate of DMS and DMSP in the field are tightly coupled to the available carbon produced by phytoplankton.

Effect of P and N addition to oligotrophic Eastern Mediterranean waters influenced by near-shore waters: A microcosm experiment

Abstract: Phosphate (P), nitrate (N) or P+N added in a microcosm experiment to oligotrophic waters of the Eastern Mediterranean influenced by near-shore waters triggered a range of responses in the autotrophic and heterotrophic compartments of the system. Chlorophyll a increased in all treatments, including the no-addition control, implying that nutrients became available also from internal sources (recycling). Larger and faster biomass increase as well as a larger P utilization took place in the P+N treatments. Diatoms bloomed in the P+N treatments whereas coccolithophores bloomed following the addition of P ultimately reaching N-limitation. Bacterial activity responded with a transient peak to both low P-alone and N-alone additions (0.01 and 1 μM, respectively). For reasons not well understood, no such response was observed at higher P-alone additions (0.05 and 0.5 μM), whereas at the two highest P+N additions the positive response was delayed. We therefore were unable to conclude conclusively on bacterial limitation. In most cases, the increase in bacterial activity was not matched by an increase in abundance, suggesting a tight top-down control of the biomass. Instead, heterotrophic nanoflagellate and ciliate abundances increased in all treatments. A slightly elevated orthophosphate turnover-time (Tt) (32 h) in the initial waters did not give a clear indication of P-limitation, although the system could absorb the lowest P-addition (0.01 μM) without increase in Tt. N alone lead to a reduction in Tt as would be expected in an N-limited system consuming existing surplus P after N-addition. The response of the near-shore influenced system used in this study was in accord with the ‘classical’ response to nutrient introduction—increase in chlorophyll a and in large size phytoplankton. In contrast, in the ultraoligotrophic Cyprus Eddy [Krom, Thingstad, Carbo, Drakopoulos, Fileman, Flaten, Groom, Herut, Kitides, Kress, Law, Liddicoact, Mantoura, Pasternak, Pitta, Polychronaki, Psarra, Rassoulzadegan, Skjoldal, Spyres, Tanaka, Tselepides, Wassmann, Wexels-Riser, Woodward, Zodiatis, Zohary, 2005. Overview of the CYCLOPS P addition lagrangian experiment in the Eastern Mediterranean. Deep-Sea Research II, this volume.], the short Tt (<4 h) indicated P-limitation, the combined addition of P and N (as ammonium) induced a bloom of picocyanobacteria [Zohary, Herut, Krom, Mantoura, Pitta, Psarra, Rasssoulzadegan, Stambler, Tanaka, Thingstad, Woodward, 2005. P-limited bacteria but N&P co-limited phytoplankton in the Eastern Mediterranean—a microcosm experiment. Deep-Sea Research II, this volume.] and the in situ P alone addition led to a decrease in chlorophyll.

Biogeochemical significance of transport exopolymer particles in the Indian Ocean

Abstract: The behavior of Transparent Exopolymer Particles (TEP), produced by biochemical processes, was studied for the North Indian Ocean, an area of global biogeochemical significance, during 1996 southwest monsoon. Very different behavior of TEP was found between waters of the Arabian Sea and the Bay of Bengal. The TEP concentrations were lower in the Bay of Bengal due to faster scavenging from water column because of interaction with mineral particles. They were higher and occurred even in intense sub-oxic layers in the Arabian Sea. Our results support the mineral ballast theory in the Bay of Bengal and also reveal the hitherto not noticed organic matter reservoir, which seems to be in surplus, to meet the higher carbon demand by bacteria in denitrifying waters of the Arabian Sea.

Growth, protein and carbohydrate contents in Ulva rigida and Gracilaria bursa-pastoris integrated with an offshore fish farm

Abstract: Low-technology practices are generally the rule when cultivating marine macroalgae, and they do not necessarily comply with sustainability requirements. When integrated with other marine organisms in land-based setups, seaweed culture can be sustainable also providing environmental benefits. Major challenges of such integrated aquaculture systems, however, are in sea-based setups. The current study examined the growth rates of Ulva rigida and Gracilaria bursa-pastoris, as well as their protein and carbohydrate contents, when exposed to different distances from an offshore, fed-fish cage system. Nutrient levels in seawater were consistently high downstream from the fish cages, significantly enhancing the specific growth rates and cellular contents of starch and soluble protein in these two seaweeds. Specifically, daily maximal growth rates were 17 % day−1 for U. rigida and 10 % day−1 for G. bursa-pastoris, maximal starch contents were 22 and 21 %, respectively, and maximal protein contents were on a dry weight basis 7 and 13 %, respectively. When repositioned at low ambient nutrient levels for 48 h, the starch and the carbohydrate levels increased by 129 and 131 % for U. rigida and by 198 and 150 % for G. bursa-pastoris, respectively. Altogether, this study supports implementing future viable mean of sustainable macroalgae cultivation by taking advantage of excessive nutrients released from an offshore fish farm.