DRS at CSIR-National Institute of Oceanography
https://drs.nio.res.in:443/drs
The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.2024-03-29T00:56:29ZMorphotectonics of the Raman-Panikkar-Wadia seamount chain in the Laxmi Basin, Eastern Arabian Sea
http://drs.nio.res.in/drs/handle/2264/9185
Morphotectonics of the Raman-Panikkar-Wadia seamount chain in the Laxmi Basin, Eastern Arabian Sea
Savio, J.J.; Yatheesh, V.; Bijesh, C.M.; Mahender, K.; Aswini, K.K.; Badesab, F.K.; Shuhail, M.; Sriram, G.; Twinkle, D.; Kumar, Raj
The Laxmi Basin, which is a deep ocean basin situating adjoining to the northwestern continental margin of India, contains a linear seamount chain consisting of the Raman Seamount, Panikkar Seamount and the Wadia Guyot, located over the axial basement high in the Laxmi Basin representing the Panikkar Ridge. The geomorphology of this seamount chain was studied by earlier researchers; however, its characteristic geophysical signatures, possible genesis and age of formation remains to be clearly established. We attempted for a detailed understanding of the morphological characteristics and the geophysical signatures over the spatial extent of these seamounts using a fresh set of multibeam bathymetry data and sea-surface gravity and magnetic anomalies, complemented by the existing seismic reflection sections. Based on the seafloor and basement topography signatures observed together from the multibeam bathymetry data and the seismic reflection sections, we infer that all the three seamounts are associated with the presence of surface/subsurface secondary peaks on their central parts. The free-air gravity anomaly maps show that the seamounts are associated with a very short wavelength gravity high, superimposed on the short wavelength gravity low representing the Panikkar Ridge. The magnetic anomaly maps suggest that all these seamounts are associated with complex magnetic signatures. Based on the presence of morphological features that are generally associated with the volcanic activity and by considering the above complex geophysical signatures and the updated magnetic isochron map of the Laxmi Basin, we support multiphased volcanic origin for the Raman-Panikkar-Wadia seamount chain, emplaced at an age younger to 63.28 Ma.
IF(JCR2023) = 3
2024-01-01T00:00:00ZBeneficial properties of mucus in coral adaptations and ecological interactions
http://drs.nio.res.in/drs/handle/2264/9184
Beneficial properties of mucus in coral adaptations and ecological interactions
Bhagwat, P.V.; Ravindran, C.; Lawrance, I.
Coral mucus secreted by mucocytes provides a protective physicochemical and physiological barrier between coral tissue and external environmental threats. The biomolecules and nutrients of the secreted mucus are derived from endosymbionts, coral polyps and support coral functions, such as feeding, sediment clearing and protection, against numerous biotic and abiotic stressors. The surface mucus layer also houses a diverse community of beneficial microorganisms that defend against pathogens. Enzymes including peptidases, esterases, and glycosidases were observed and described in mucus. Most importantly, the presence of phenoloxidase, an intracellular enzyme in secretory mucus, generally triggers melanin synthesis, providing fast-acting components of invertebrate immunity in disease resistance. However, the purpose and the mechanism of mucus release, effects of mucus components on defense properties, and functional roles in intra- and interspecific interactions are not well described. Thus, the present review aims to understand the mucus components and the complex roles played by mucus in microbial associations, feeding, and resilience that influence coral health.
IF(JCR2023) = 2.4
2024-01-01T00:00:00ZAntimicrobial activity of coral-associated beneficial bacteria against coral disease-causing microbial pathogens
http://drs.nio.res.in/drs/handle/2264/9183
Antimicrobial activity of coral-associated beneficial bacteria against coral disease-causing microbial pathogens
Lawrance, I.; Ravindran, C.; Haritha, P.R.
Microbial infection of immune-compromised corals influences disease severity, resulting in coral mortality. However, coral-associated beneficial bacteria are known to produce antimicrobial compounds that prevent the growth of potential pathogens and invading microbes. Hence, beneficial bacteria associated with coral Porites lutea were isolated and antimicrobial protein and bioactive secondary metabolites were extracted and tested for their antimicrobial activity against putative prokaryotic and eukaryotic coral pathogens. Bioactive secondary metabolites exhibited remarkable antagonism against various coral pathogens such as Serratia marcescens, Vibrio species, and Aspergillus sydowii. Besides, the metabolites of Cobetia marina, Cobetia amphilecti, Pseudoalteromonas neustonica, and Virgibacillus halodenitrificans manifested notable inhibition against the protozoan ciliates (Uronema marinum, Holosticha diademata, Cohnilembus verminus, and Euplotes vannus) and zooplankton that are known to be involved in the secondary pathogenesis in coral diseased lesion progression. Thus, the present study may benefit in understanding coral-associated beneficial bacteria for their antagonistic interactions with microbial pathogens, as well as their potential involvement in reducing coral disease severity.
IF(JCR2023) = 3.1
2024-01-01T00:00:00ZExport of particulate organic carbon and nitrogen to the northern Indian Ocean by the monsoonal rivers of India
http://drs.nio.res.in/drs/handle/2264/9181
Export of particulate organic carbon and nitrogen to the northern Indian Ocean by the monsoonal rivers of India
Krishna, M.S.; Prasad, M.H.K.; Naidu, S.A.; Srikanth, G.; Reddy, N.P.C.; Sarma, N.S.
This study analyses particulate organic carbon (POC) and particulate nitrogen (PN) export from Indian monsoonal rivers to the north Indian Ocean. Indian monsoonal rivers export approximately 1.2 Tg yr?1 (1Tg?=?1012 g) of POC and 0.14 Tg yr?1 of PN, with about two-thirds entering the Bay of Bengal (0.8 and 0.1 Tg yr?1, respectively) and the remaining reaches to the Arabian Sea (0.4 and 0.04 Tg yr?1, respectively). Remarkably, just four rivers from northwest India�s black soil-dominated regions contribute about half of the total POC and PN exports (0.64 and 0.06 Tg yr?1, respectively). This is due to substantial erosion in these catchments, resulting in suspended matter concentrations averaging 596?�?252 mg L?1, significantly higher than catchments dominated by red sandy, red loamy and alluvial soils (54?�?56 mg l?1). In contrast, rivers originating from catchments with heavy precipitation, a tropical wet climate, red loamy soils (with peaty and marshy characteristics), rich tropical wet evergreen and moist deciduous forests, and higher soil organic carbon content yield more POC and PN (1704?�?383 kgC km?2 yr?1 and 261?�?56 kgN km?2 yr?1, respectively) than the other rivers of India (951?�?508 kgC km?2 yr?1 and 120?�?57 kgN km?2 yr?1, respectively). These findings stress that the export flux and yield of POC and PN from the Indian monsoonal rivers are primarily influenced by the interplay of hydrological, lithological, environmental, and climatic conditions within the catchment, rather than river size. Moreover, this study highlights the significant impact of incorporating POC data from medium-sized rivers worldwide, as it reveals that yield is independent of river size. This calls for a re-evaluation of global POC export fluxes, taking into account hydrological, lithological, environmental, and climatic factors.
IF(JCR2023) = 5.8
2023-01-01T00:00:00Z