Can benthic foraminiferal morpho-groups be used as indicators of paleomonsoonal precipitation?

Nigam, R.; Khare, Neloy; Borole, D.V.

doi:10.1016/s0272-7714(05)80060-5

Cited by 18 publications

(17 citation statements)

References 25 publications

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“…The fluctuations in riverine influx are related to the changes in monsoon intensity in the adjacent areas (Durand et al 2011). Therefore, we suggest that changes in relative abundance of AABF and RSBF can be effectively used for the paleomonsoon reconstruction and freshwater intensity reconstruction from the core collected from the northwestern Bay of Bengal, as previously applied in the Arabian Sea and central Bay of Bengal (Nigam et al 1992;Nigam and Khare 1994;Rana and Nigam 2009).…”

Section: Discussionmentioning

confidence: 72%

“…Nonions being round in shape, can survive in high energy environment as they are found in the inner shelf region (0-100 m water depth) (Murray 1991;Nigam et al 1992;Nigam and Khare 1994). According to Murray (2006), the salinity preference of Nonions ranges from 32-35 psu.…”

Section: Discussionmentioning

confidence: 99%

“…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%

“…Different colonization stages can be observed in these unique micro-environments wherein foraminifera respond with an opportunistic strategy (Fontanier et al 2002(Fontanier et al , 2008Mojtahid 2009;Goineau et al 2011Goineau et al , 2012. The unique environmental conditions with a combination of enhanced productivity combined with low oxygen conditions in the riverine influx region thus result in reduced species diversity and predominance of a single species or a morpho-group (Severin 1983;Nigam et al 1992Nigam et al , 2000Nigam andKhare 1994, 1999;Jayaraju and Reddy 1997;Rana and Nigam 2009). Utilizing the presence of characteristic fauna in river-dominated marginal marine regions, the ratio of angular asymmetrical to rounded symmetrical benthic foraminifera, was suggested as a tool to reconstruct past monsoon intensity (Nigam et al 1992).…”

Section: Introductionmentioning

confidence: 99%

“…The unique environmental conditions with a combination of enhanced productivity combined with low oxygen conditions in the riverine influx region thus result in reduced species diversity and predominance of a single species or a morpho-group (Severin 1983;Nigam et al 1992Nigam et al , 2000Nigam andKhare 1994, 1999;Jayaraju and Reddy 1997;Rana and Nigam 2009). Utilizing the presence of characteristic fauna in river-dominated marginal marine regions, the ratio of angular asymmetrical to rounded symmetrical benthic foraminifera, was suggested as a tool to reconstruct past monsoon intensity (Nigam et al 1992). The method has the advantage of circumventing the need to identify all the benthic foraminifera up to species level, which is required when benthic foraminiferal species assemblages are used to reconstruct past monsoon.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 72%