A Spatial Ecological Study Based on Benthic Foraminifera off Central West Coast of India: An Approach through Cluster Analysis with Special Reference to Oxygen Minimum Zone

2020 ◽  
Author(s):  
Abhijit Mazumder ◽  
Rajiv Nigam
Keyword(s):  
Cluster Analysis ◽  
Special Reference ◽  
West Coast ◽  
Benthic Foraminifera ◽  
Ecological Study ◽  
Oxygen Minimum Zone ◽  
West Coast Of India ◽  
Minimum Zone ◽  
Oxygen Minimum

scholarly journals I/Ca ratios in benthic foraminifera from the Peruvian oxygen minimum zone: analytical methodology and evaluation as proxy for redox conditions

2014 ◽  
Vol 11 (7) ◽  
pp. 11635-11670 ◽  
Author(s):  
N. Glock ◽  
V. Liebetrau ◽  
A. Eisenhauer
Keyword(s):  
Benthic Foraminifera ◽  
Oxygen Minimum Zone ◽  
Individual Variability ◽  
Redox Conditions ◽  
Positive Trend ◽  
Analytical Methodology ◽  
Foraminiferal Species ◽  
Minimum Zone ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

Abstract. In this study we explore the correlation of I/Ca ratios in three calcitic and one aragonitic foraminiferal species. I/Ca ratios are evaluated as possible proxies for changes in ambient redox conditions across the Peruvian oxygen minimum zone to the ambient oxygen concentrations in the habitat of the foraminiferal species studied. We test cleaning and measurement methods to determine I/Ca ratios in benthic foraminifera from the Peruvian oxygen minimum zone. All species show a positive trend in their I/Ca ratios as a function of higher oxygen concentrations and these trends are all statistically significant except for the aragonitic species Hoeglundina elegans. The most promising species appears to be Uvigerina striata which shows a highly statistically significant correlation between I/Ca ratios and bottom water (BW) oxygenation (I/Ca = 0.032(± 0.004)[O2]BW + 0.29(± 0.03), R2 = 0.61, F = 75, P < 0.0001). Although I/Ca ratios in benthic foraminifera might prove to be a valuable proxy for changing redox-conditions the iodine volatility in acidic solutions, the species dependency ofI/Ca–[O2]BW correlations, and the individual variability of single tests severely interfere with the observed I/Ca–[O2]BW relationship.

scholarly journals Benthic Foraminifera from Middle to Late Pleistocene, coastal upwelling sediments of ODP Hole 686B, Pacific Ocean, off Peru

1991 ◽  
Vol 9 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Kathryn A. Malmgren ◽  
Brian M. Funnell
Keyword(s):  
Late Pleistocene ◽  
Surface Waters ◽  
Benthic Foraminifera ◽  
Bottom Water ◽  
Coastal Upwelling ◽  
Oxygen Minimum Zone ◽  
Water Oxygen ◽  
Minimum Zone ◽  
Water Depths ◽  
Oxygen Minimum

Abstract. Benthic Foraminifera from middle to late Pleistocene, (c. 600ka to 0ka), sediments of ODP Hole 686B, off Peru, show highest abundances and diversities during periods of cooler surface waters, (inferred from the Uk37 index), and enhanced upwelling, (inferred from the peridinacean/gonyaulacacean dinoflagellate cyst ratio). During the latest Pleistocene, (c. 160ka to 0ka), these periods are characterised by higher organic carbon contents in the bottom sediments, and occur during the odd-numbered, interglacial_18O stages. The benthic Foraminifera indicate deposition in 120 to 250 metres water depth for the earlier part of the record, (c. 600ka to c. 200ka), within the oxygen-minimum zone, with bottom water oxygen contents of <0.5 to 0.2 ml/l, (inferred from the dominance of Bolivinellina humilis). Deposition in water depths approaching those of the present day, (c. 450 metres), is indicated from c. 160ka onwards, with better oxygenated bottom water conditions, probably corresponding to the lower part of the oxygen-minimum zone.

scholarly journals The role of benthic foraminifera in the benthic nitrogen cycle of the Peruvian oxygen minimum zone

2012 ◽  
Vol 9 (12) ◽  
pp. 17775-17817 ◽  
Author(s):  
N. Glock ◽  
J. Schönfeld ◽  
A. Eisenhauer ◽  
C. Hensen ◽  
J. Mallon ◽  
...  
Keyword(s):  
Benthic Foraminifera ◽  
Oxygen Minimum Zone ◽  
Substantial Contribution ◽  
Individual Species ◽  
Intermediate Water ◽  
Near Surface ◽  
Nitrate Loss ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. The discovery that foraminifera are able to use nitrate instead of oxygen as energy source for their metabolism has challenged our understanding of nitrogen cycling in the ocean. It was evident before that only prokaryotes and fungi are able to denitrify. Rate estimates of foraminiferal denitrification were very sparse on a regional scale. Here, we present estimates of benthic foraminiferal denitrification rates from six stations at intermediate water depths in and below the Peruvian oxygen minimum zone (OMZ). Foraminiferal denitrification rates were calculated from abundance and assemblage composition of the total living fauna in both, surface and subsurface sediments, as well as from individual species specific denitrification rates. A comparison with total benthic denitrification rates as inferred by biogeochemical models revealed that benthic foraminifera account for the total denitrification on the shelf between 80 and 250 m water depth. They are still important denitrifiers in the centre of the OMZ around 320 m (29–56% of the benthic denitrification) but play only a minor role at the lower OMZ boundary and below the OMZ between 465 and 700 m (3–7% of total benthic denitrification). Furthermore, foraminiferal denitrification was compared to the total benthic nitrate loss measured during benthic chamber experiments. Foraminiferal denitrification contributes 1 to 50% to the total nitrate loss across a depth transect from 80 to 700 m, respectively. Flux rate estimates ranged from 0.01 to 1.3 mmol m−2 d−1. Furthermore we show that the amount of nitrate stored in living benthic foraminifera (3 to 705 µmol L−1) can be higher by three orders of magnitude as compared to the ambient pore waters in near surface sediments sustaining an important nitrate reservoir in Peruvian OMZ sediments. The substantial contribution of foraminiferal nitrate respiration to total benthic nitrate loss at the Peruvian margin, which is one of the main nitrate sink regions in the world oceans, underpins the importance of previously underestimated role of benthic foraminifera in global biochemical cycles.

Live (Rose Bengal stained) and dead benthic foraminifera from the oxygen minimum zone of the Pakistan continental margin (Arabian Sea)

2007 ◽  
Vol 62 (1) ◽  
pp. 45-73 ◽  
Author(s):  
Stefanie Schumacher ◽  
Frans J. Jorissen ◽  
Delphine Dissard ◽  
Kate E. Larkin ◽  
Andrew J. Gooday
Keyword(s):  
Continental Margin ◽  
Rose Bengal ◽  
Benthic Foraminifera ◽  
Arabian Sea ◽  
Oxygen Minimum Zone ◽  
Minimum Zone ◽  
Oxygen Minimum
Sign in / Sign up

Export Citation Format

Share Document