• Vijaya

      Articles written in Journal of Earth System Science

    • Fine-scale responses of phytoplankton to freshwater influx in a tropical monsoonal estuary following the onset of southwest monsoon

      Suraksha M Pednekar S G Prabhu Matondkar Helga Do R Gomes Joaquim I Goes Sushma Parab Vijaya Kerkar

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      In May of 2007, a study was initiated by the National Institute of Oceanography (NIO), Goa, India, to investigate the influence of monsoonal rainfall on hydrographic conditions in the Mandovi River of India. The study was undertaken at a location ∼2 km upstream of the mouth of this estuary. During the premonsoon (PreM) in May, when circulation in the estuary was dominated by tidal activity, phytoplankton communities in the high saline (35–37 psu) waters at the study site were largely made up of the coastal neritic species Fragilaria oceanica, Ditylum brightwellii and Trichodesmium erythraeum. During the later part of the intermonsoon (InterM) phase, an abrupt decline in salinity led to a surge in phytoplankton biomass (Chlorophyll 𝑎 ∼14 mg m−3), of a population that was dominated by Thalassiosira eccentricus. As the southwest monsoon (SWM) progressed and the estuary freshened salinity and Chlorophyll 𝑎 (Chl 𝑎) concentrations decreased during the MoN, Skeletonema costatum established itself as the dominant form. Despite the low biomass (Chl 𝑎 > 2 mg m−3), the phytoplankton community of the MoN was the most diverse of the entire study. During the postmonsoon (PostM), the increase in salinity was marked by a surge in dinoflagellate populations comprising of Ceratium furca, Akashiwo sanguinea, and Pyrophacus horologium.

    • Stratigraphic status of coal horizon in Tatapani–Ramkola Coalfield, Chhattisgarh, India

      Archana Tripathi Vijaya Srikanta Murthy B Chakarborty D K Das

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      The palynostratigraphic data given here are based on the explored borecores (TRBD-2, TRBD-3 and TROD-1), by Geological Survey of India. The Permian strata worked-out is about 1174.00 m thick and comprises from base to top – Talchir, Barakar and Barren Measures formations. The palynological content enables delimitation of five palynological assemblages. (i) Scheuringipollenites barakarensis, (ii) Faunipollenites varius, (iii) Gondisporites raniganjensis, (iv) Densipollenites magnicorpus, and (v) Krempipollenites indicus in ascending order from the subsuface rock strata. The lithologically identified strata Talchir Formation in borecores TRBD-2 and TRBD-3 is palynologically dated late Early Permian in having the Scheuringipollenites barakarensis and the Faunipollenites varius palynozones. Subsequently, the part of Barakar strata in these borecores corroborates with Barakar Formation. In borecore TRBD-3, the Barren Measures rocks do not match with the palynological dates, and are affiliated with the palynoflora of the Raniganj Formation. In TROD-1, the strata identified as Barakar Formation is dated Late Permian in having Gondisporites ranigangensis Palynozone; while that of Barren Measures Formation is palynologically dated Early Triassic having Krempipollenites indicus Palynozone. The palynology has helped in the precise dating of the Lower Gondwana succession of Odari and Bartikhurd blocks in Tatapani–Ramkola Coalfield of South Rewa Gondwana Basin.

    • Palynostratigraphy and age correlation of subsurface strata within the sub-basins in Singrauli Gondwana Basin, India

      Vijaya Archana Tripathi A Roy Saibal Mitra

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      In the study area, changes in the facies of sediments and spores-pollen content appear to be all causally linked with the depositional set-up. Here, the qualitative and quantitative changes observed in the spores-pollen assemblages have led to recognize 10 Assemblage-zones representing from that earliest Permian in the Talchir Formation to that latest Late Triassic in the Parsora Formation. These sporespollen assemblages are obtained from the wider parts in the Singrauli Gondwana Basin that includes (i) Moher sub-basin (boreholes SSM-1 and 2), and (ii) Singrauli main sub-basin (boreholes SMJS-2, 3 and SMBS-1). The progressively changing spores-pollen content infer the hiatuses of varied magnitude in the sedimentary sequences during the extended time interval of Permian and Triassic.

    • Artificial coastal defence structures – A surrogate of natural rocky structure to enhance coastal biodiversity


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      The world's 40% of the population lives in coastal areas ( <150 km from the sea), and this is set to increase in upcoming years. This urban sprawl leads to the proliferation of artificial coastal defence structures along the coasts to save the populace from coastal erosion, storms, and hurricanes. Deployment of artificial coastal defence structures has direct or indirect impacts on the local and global scenario, but the ecology of artificial habitats was studied poorly. Therefore, the current study aimed to focus on the role of artificial coastal defence structures in enhancing the coastal biodiversity. A total of 228 epibiotic species associated with the artificial coastal defence structures were identified. The study recorded high species richness and diversity of epibenthos in artificial habitats compared to natural habitats. Among various types of artificial habitats, assemblage pattern of epibiotic species in sandstone surfaces differs from non-sandstone surfaces. Apart from the structure surface, local epibenthic biodiversity also plays a significant role in determining the artificial structure assemblages. The length, vertical height, and age of the structures are the major deciding factors in species composition of the structures. The overall study concluded that the artificial coastal defence structures could act as a surrogate surface for epibiotic assemblages. The input of coastal biodiversity component while designing the artificial coastal defence structures can be an added advantage.

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