Rapid switch in monsoon-wind induced surface hydrographic conditions of the eastern Arabian Sea during the last deglaciation

Singh, Arun D.; Jung, Simon; Anand, Pallavi; Kroon, Dick; Ganeshram, Raja S.

doi:10.1016/j.quaint.2018.03.027

Cited by 26 publications

(16 citation statements)

References 52 publications

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“…The advantage of this palaeo-productivity proxy is that it is unaffected by dissolution artefacts in the sediment, as both species are equally sensitive to dissolution (Cullen & Prell, 1984;Conan et al 2002). Hence, G. bulloides / G. ruber ratio is a robust proxy and this has been used previously for palaeoceanographic reconstructions in the EAS (Singh et al 2006(Singh et al , 2011(Singh et al , 2018.…”

Section: B Analytical Methodsmentioning

confidence: 98%

“…Therefore, planktic foraminiferal assemblages in sediment have great potential for reconstructing past surface ocean conditions (e.g. Ravelo et al 1990;Kroon et al 1991;Singh et al 2006Singh et al , 2018. We examined variations of foraminiferal proxies (absolute abundances of ecologically sensitive species and mixed layer eutrophic and oligotrophic species abundance ratio) to understand the temporal variability of the surface water hydrography, viz.…”

Section: B Analytical Methodsmentioning

confidence: 99%

“…Clemens et al 1991;Anderson & Prell, 1993;Vénec-Peyré et al 1995;Naidu & Malmgren, 1996;Reichart et al 1998;Schulz et al 1998;von Rad et al 1999;Schulte & Müller, 2001;Jung et al 2002;Gupta et al 2003;Ivanova et al 2003;Ivanochko et al 2005). Earlier studies suggested that fossil planktic foraminiferal assemblages in the eastern Arabian Sea (EAS) record primarily winter monsoon induced changes in surface water oceanographic conditions (Singh et al 2006(Singh et al , 2011(Singh et al , 2018, because winter monsoon winds play a dominant role in surface hydrography and biological productivity. Most of the previous palaeoceanographic reconstructions based on planktic foraminiferal assemblages and geochemical proxies (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the previous palaeoceanographic reconstructions based on planktic foraminiferal assemblages and geochemical proxies (e.g. stable isotopes and Mg/Ca-based sea surface temperature (SST)) from the EAS mainly focused on the last glacial-interglacial cycle (Cayre & Bard, 1999;Thamban et al 2001;Ivanova et al 2003;Pattan et al 2003;Banakar et al 2005;Chodankar et al 2005;Guptha et al 2005;Singh et al 2006Singh et al , 2011Singh et al , 2018Anand et al 2008). However, no record of millennial-to orbital-scale variations from this region is currently available extending beyond the last glacial-interglacial cycle, particularly for the early Pleistocene, which has been suggested as a period when a major reorganization of atmospheric circulation from a weak to a strong zonal Walker circulation took place (Etourneau et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Monsoon-induced changes in surface hydrography of the eastern Arabian Sea during the early Pleistocene

2019

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Upper water column dynamics in the eastern Arabian Sea were reconstructed in order to investigate changes in the activity of the South Asian / Indian monsoon during the early Pleistocene (c. 1.5–2.7 Ma). We used planktic foraminiferal assemblage records combined with isotopic (δ18O and δ13C) data, Mg/Ca-based sea surface temperatures and seawater δ18O records to estimate changes in surface water conditions at International Ocean Discovery Program (IODP) Site U1457. Our records indicate two distinct regimes of monsoon-induced changes in upper water structure during the periods c. 1.55–1.65 Ma and c. 1.85–2.7 Ma. We infer that a more stratified upper water column and oligotrophic mixed layer conditions prevailed during the period 1.85–2.7 Ma, which may be due to overall weaker South Asian / Indian winter (NE) and summer (SW) monsoon circulations. The period 1.55–1.65 Ma was characterized by enhanced eutrophication of the mixed layer, which was probably triggered by intensified winter (NE) monsoonal winds. The long-term trend in hydrographic changes during 1.55–1.65 Ma appears to be superimposed by short-term variations, probably reflecting glacial/interglacial changes. We suggest that an intensification of the South Asian / Indian winter monsoon circulation occurred between ∼1.65 Ma and 1.85 Ma, which is most likely due to the development of strong meridional and zonal atmospheric circulations (i.e. Walker Circulation and Hadley Circulation) because of strong equatorial East–West Pacific temperature gradients.

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Section: B Analytical Methodsmentioning

confidence: 98%

Section: B Analytical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Monsoon-induced changes in surface hydrography of the eastern Arabian Sea during the early Pleistocene

2019

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“…The eastern Arabian Sea sediment records are ideal to investigate winter monsoon variability, as hydrography and productivity in this region is primarily driven by the northeasterly winter monsoon winds. In recent past, some important studies on winter monsoon variation on millennial to orbital time scales have been carried out based on late Quaternary foraminiferal assemblages, Mg/Ca based temperature and stable oxygen isotope records from the central part of eastern Arabian Sea Indian margin (Singh et al, 2011(Singh et al, , 2018Cabarcos et al, 2014;Anand et al, 2008). But, until recently no record was available for the crucial period of climatic transition from the Late Pliocene to the Early Pleistocene, when a major reorganization of atmospheric circulation from a weak to strong zonal and meridional atmospheric circulations took place (eg.…”

Section: Records Of Past Changes In Ocean-climate During the Neogenementioning

confidence: 99%

Recent advances in understanding Neogene climatic evolution: Indian perspective

Singh¹,

Ghosh²,

Mehrotra³

et al. 2020

PINSA

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This article presents an overview of the research work done during 2015-2019 on the South Asian/Indian monsoon climate variability, based on the Neogene terrestrial and marine proxy records. The paleoclimatic and paleoceanographic records provide better insights into our current understanding of timing of initiation/intensification of the Indian monsoon system; its evolution and seasonal variability pattern through time and underlying mechanisms; and impacts on paleobiogeography of terrestrial fauna and flora and physico-chemical and biological processes in the northern Indian Ocean. The Neogene upliftment history of the Himalaya was reconstructed based on detailed analysis of fossil flora from Himalayan sequences and a link between step wise uplift of Himalaya-Tibetan plateau and Indian summer monsoon intensification was established. The rainfall pattern in the northeast India during the Neogene period was quantified; and the new data suggest the presence of rainfall in the region since 11.6 Ma. δ 13 C record of pedogenic nodules in Siwalik succession provides evidence of major shift in vegetation between ~2.8 Ma and 1.1 Ma due to large variation in temperature and precipitation. New results of the multiproxy based paleoceanographic studies carried out on sediment cores collected during recent IODP expeditions in the Arabian Sea and Bay of Bengal, have major implications on the evolution of the Indian monsoon and dynamics of its seasonal variations in the Neogene. The sedimentological and geochemical records from carbonate platform of the Maldives suggest an abrupt onset of modern monsoon circulation at ~ 12.9 Ma, which cannot be entirely explained by the Himalayan tectonics as many believed earlier. It appears that the global climate also controls Indian monsoon circulation, in addition to the tectonics. Record of past changes in the Arabian Sea denitrification driven mainly by monsoon-wind induced productivity and water column ventilation condition, reveals that the Indian monsoon intensified during ~2.8-3.2 Ma. Recently, based on the integrated multiple proxy records it was inferred that seasonal monsoon circulation was weak during 1.85-2.7 Ma, subsequently followed by the intensification of winter monsoon between ~1.65 and 1.85 Ma, attributed to the development of strong zonal and meridional circulations due to enhanced E-W Pacific temperature gradients.

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Gone with the wind: Seasonal distribution and habitat use by the reef manta ray (Mobula alfredi) in the Maldives, implications for conservation

Harris

McGregor

Oates

et al. 2020

Aquatic Conservation

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Reef manta rays (Mobula alfredi) are one of the ocean's largest and most charismatic species. Pressure from targeted and bycatch fisheries coupled with their conservative life‐history traits including slow growth, late maturity, and low fecundity has led to catastrophic declines of the global population. The species is now listed as Vulnerable to Extinction on IUCN Red List of Threatened Species. The global M. alfredi population is widely distributed in highly fragmented subpopulations. The Maldives supports the world's largest known subpopulation that undergoes seasonal migrations which are thought to be linked to peaks in ocean productivity induced by the South Asian Monsoon. Although the species is protected from targeted fisheries in the region, increasing pressures from habitat degradation and unsustainable tourism activities mean their effective conservation relies upon knowledge of the species' habitat use, seasonal distribution, and the environmental influences on such movements. Photo‐ID sighting records collected between 2005 and 2017 were used to identify key aggregation sites throughout the archipelago, and multiple linear regression and prediction analysis identified the environmental variables affecting variations in the intra‐annual sighting frequency of M. alfredi. Mobula alfredi were recorded at 273 different sites, 48 of which, with >100 sightings at each, were classified as key areas of habitat use. South‐west monsoon winds and chlorophyll‐a concentration predominantly affected the monthly percentage of M. alfredi sighted on the down‐current side of the atolls. In a country where climate change and touristic pressure are increasingly threatening this species and its habitat, the identification of key areas of habitat use and temporal changes in the use of these sites highlight the areas that should be prioritized for protection enabling more effective conservation management.

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Rapid switch in monsoon-wind induced surface hydrographic conditions of the eastern Arabian Sea during the last deglaciation

Abstract: Rapid switch in monsoon-wind induced surface hydrographic conditions of the eastern Arabian Sea during the last deglaciation. Quaternary International, 479 pp. 3-11. For guidance on citations see FAQs.

Cited by 26 publications

References 52 publications

Monsoon-induced changes in surface hydrography of the eastern Arabian Sea during the early Pleistocene

Monsoon-induced changes in surface hydrography of the eastern Arabian Sea during the early Pleistocene

Recent advances in understanding Neogene climatic evolution: Indian perspective

Gone with the wind: Seasonal distribution and habitat use by the reef manta ray (Mobula alfredi) in the Maldives, implications for conservation

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