Spatial and Temporal Distribution of Foraminifera in Sediments off the Central West Coast of India and Use of Their Test Morphologies for the Reconstruction of Paleomonsoonal Precipitation

Nigam, R.; Khare, Neloy

doi:10.2307/1486138

Cited by 25 publications

(9 citation statements)

References 3 publications

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“…Temporal changes in benthic foraminiferal morphogroups, in cores collected from shallow marine regions influenced by riverine influx, were suggested as an efficient proxy to reconstruct past monsoon intensity (Nigam et al 1992(Nigam et al , 1995Nigam and Khare 1999). The characteristic benthic foraminiferal assemblages in river dominated ocean margins are the result of the timing and extent of unique biogeochemical processes in both the water column as well as sediment.…”

Section: Introductionmentioning

confidence: 99%

Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

2016

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Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstruct past monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporal variation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we have documented recent benthic foraminiferal distribution from the continental shelf region of the northwestern Bay of Bengal. Based on the external morphology, benthic foraminifera were categorized into rounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, a few other dominant groups were also identified based on test composition (agglutinated, calcareous) and abundance (Asterorotalids and Nonions). The relative abundance of each group was compared with the ambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature. We report that the RSBF are abundant in comparatively warm and well oxygenated waters of low salinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold, hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinated foraminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereas the calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Food availability, as estimated from organic carbon abundance in sediments, has comparatively less influence on faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperature and salinity. We conclude that the factors associated with freshwater influx affect the distribution of benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used to reconstruct past monsoon intensity from the Bay of Bengal.

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Section: Introductionmentioning

confidence: 99%

Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

2016

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“…Boltovskoy and Wright (1976) expressed similar views about the benthic foraminifera in general while stating that under normal condition number of megalospheric specimens always outnumber the microspheric specimens. As the morphological variations of the test, as well as the variation in distribution of benthic foraminifera have previously been applied to infer past climatic variations from the west coast of India (Nigam and Rao, 1989;Nigam and Khare, 1992;Nigam and Khare, 1999) the present study suggests that morphologic variations of E. exigua can also be applied to infer paleoclimatic conditions.…”

Section: Resultsmentioning

confidence: 67%

“…Besides assemblage, isotopic and elemental composition, abundance and morphology of a few foraminiferal species vary with ambient conditions and are used as paleoclimatic proxy (Thiede, 1971;Prell, 1984;Nigam and Rao, 1987;1989;Anderson and Prell, 1993;Nigam and Khare, 1999;Peeters et al 2002;Zaric et al 2005;Saraswat et al 2005a, b). The abundance and morphology of benthic foraminifera is closely associated with the reproduction which depends on the ambient environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Relationship between Abundance and Morphology of Benthic Foraminifera Epistominella exigua: Paleoclimatic Implications

Saraswat

Deopujari

Nigam

et al. 2011

Journal of the Geological Society of India

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The relationship between abundance (relative as well as absolute abundance) and morphology (size of the shell, number of chambers and proloculus size) of benthic foraminifera Epistominella exigua has been studied in a core to understand the influence of changing environmental conditions on its morphology and distribution. A total of 50 samples from the top 100 cm section of a gravity core collected from the southern Bay of Bengal Fan were used. The changes in abundance of E. exigua match well with variation in average proloculus size of E. exigua. An opposite relationship however, is observed between the abundance and size of E. exigua shells. The higher abundance corresponds with smaller E. exigua shells. Similarly, the increased E. exigua abundance matches with a decrease in the number of chambers. The increased abundance of E. exigua shows favourable conditions for its growth and survival. Thus the study indicates that during favourable conditions, while the number of chambers in the shells and the size of the shells of E. exigua decreases, more number of specimens have a larger proloculus. Since asexual reproduction results in megalospheric specimens with larger proloculus, smaller size and less number of chambers, it is inferred that E. exigua prefers an asexual mode of reproduction during favorable conditions. The findings can be used to apply morphological characteristics of E. exigua as a proxy to infer past climatic conditions.

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“…Longitudinally it occurs between 106°E (Pulau Pari, Sumatra [ Tomascik et al , 1997]) and 22.5°E (Queensland, Australia [ Palmieri , 1976]). A. gaimardii is reported by Bhatia [1956] and Nigame and Khare [1999] off the west coast of India and possibly from the Mediterranean [ Murray , 1991]. Pseudorotalia schroeteriana is a relatively rare species (Figure 6) that is present from 22.5°N (Hong Kong [ Li and Yim , 1988]) to 26°S (Queensland, Australia [ Palmieri , 1976]).…”

Section: Resultsmentioning

confidence: 99%

Neogene history of the West Pacific Warm Pool, Kuroshio and Leeuwin currents

et al. 2009

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Foraminiferal analysis of Miocene to recent strata of the Northwest Shelf of Australia is used to chart West Pacific Warm Pool (WPWP) influence. The assemblage is typified by “larger” foraminifera with ingressions of the Indo‐Pacific “smaller” taxa Asterorotalia and Pseudorotalia at around 4 Ma and from 1.6 to 0.8 Ma. A review of recent and fossil biogeography of these taxa suggests their stratigraphic distribution can be used to document WPWP evolution. From 10 to 4.4 Ma a lack of biogeographic connectivity between the Pacific and Indian Ocean suggests Indonesian Throughflow (ITF) restriction. During this period, the collision of Australia and Asia trapped warmer waters in the Pacific, creating a central WPWP biogeographic province from the equator to 26°N. By 3 Ma Indo‐Pacific species migrated to Japan with the initiation of the “modern” Kuroshio Current coinciding with the intensification of the North Pacific Gyre and Northern Hemisphere ice sheet expansion. Indo‐Pacific taxa migrated to the northwest Australia from 4.4 to 4 Ma possibly because of limited ITF. The absence of Indo‐Pacific taxa in northwest Australia indicates possible ITF restriction from 4 to 1.6 Ma. Full northwest Australian biogeographic connectivity with the WPWP from 1.6 to 0.8 Ma suggests an unrestricted stronger ITF (compared to today) and the initiation of the modern Leeuwin Current. The extinction of some Indo‐Pacific species in northwest Australia after 0.8 Ma may be related to the effects of large glacial/interglacial oscillations and uplift of the Indonesian Archipelago causing Indonesian seaway restriction.

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Spatial and Temporal Distribution of Foraminifera in Sediments off the Central West Coast of India and Use of Their Test Morphologies for the Reconstruction of Paleomonsoonal Precipitation

Cited by 25 publications

References 3 publications

Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

Relationship between Abundance and Morphology of Benthic Foraminifera Epistominella exigua: Paleoclimatic Implications

Neogene history of the West Pacific Warm Pool, Kuroshio and Leeuwin currents

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