Modern Benthic Foraminifera “Phylum Foraminifera (D’Orbigny 1826)” of the Panama Bight: A Census Report Based on Thanatocoenoses from the Continental Slope

Living benthic foraminifera (>63 µm) were studied to characterize the continental slope of the Potiguar Basin (SW Atlantic). Foraminifers from the surface (0–2 cm), subsurface (2–5 cm), and integrated (0–5 cm) sediment layers were analyzed to verify their contribution to environmental characterization. It was also estimated if and which changes occur when the subsurface is added. Sampling stations were distributed in five transects in four isobaths (150, 400, 1000, and 2000 m). Sediment samples were fixed with 4% buffered formaldehyde and stained with Bengal rose. Were recorded 396 species in the surface layer, 228 in the subsurface, and 449 in integrating both layers. This study did not include tubular agglutinated species. The assemblages from 150 m isobath indicated the upper slope, from 400 m indicated the middle slope and the ones from the 2000 m indicated the lower slope. The surface layer’s assemblage at 1000 m isobath was more similar to the middle slope; in contrast, its subsurface layer´s assemblage had more similarity with the lower slope. Rarefaction curves, Permanova, and NMDS routines indicated a high resemblance between surface and integrated layers. Therefore, the first two centimeters were sufficient to characterize this region based on living benthic foraminifera.

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BENTHIC FORAMINIFERA IN THE LATE QUATERNARY SEDIMENTS ON THE EASTERN CONTINENTAL SLOPE OF KAMCHATKA (CORE SO201-2-12KL)

Journal of Oceanological Research ◽

10.29006/1564-2291.jor-2018.46(1).4 ◽

2018 ◽

Vol 46 (1) ◽

pp. 39-55

Author(s):

Kh.M. Saidova ◽

Keyword(s):

Continental Slope ◽

Benthic Foraminifera ◽

Late Quaternary ◽

Quaternary Sediments

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The distribution of living benthic foraminifera on the continental slope and rise off southwest Norway

Marine Micropaleontology ◽

10.1016/0377-8398(85)90001-5 ◽

1985 ◽

Vol 9 (4) ◽

pp. 275-306 ◽

Cited By ~ 197

Author(s):

A. Mackensen ◽

H.P. Sejrup ◽

E. Jansen

Keyword(s):

Continental Slope ◽

Benthic Foraminifera

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Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian Margin (Arabian Sea)

Biogeosciences Discussions ◽

10.5194/bgd-10-15305-2013 ◽

2013 ◽

Vol 10 (9) ◽

pp. 15305-15335 ◽

Cited By ~ 1

Author(s):

A. J. Enge ◽

U. Witte ◽

M. Kucera ◽

P. Heinz

Keyword(s):

Continental Slope ◽

Benthic Foraminifera ◽

Arabian Sea ◽

Isotope Labeling ◽

Oxygen Depletion ◽

Food Delivery ◽

Short Term ◽

Important Species ◽

Minimum Zone ◽

Species Specific

Abstract. Benthic foraminifera in sediments on the Indian margin of the Arabian Sea where the oxygen minimum zone (OMZ) impinges on the continental slope are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L−1 (4.5 μmol L−1), an in situ isotope labeling experiment (13C, 15N) was performed at the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 ind. 10 cm−2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminifera population at 0–1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up the labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m−2 (17.5% of the total added carbon). The uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m−2 (2% of the total added nitrogen) and showed the successful application of 15N as tracer in foraminiferal studies. The short-term response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest that the observed species-specific differences are related to individual biomass of species and to specific feeding preferences. The high numbers of living foraminifera and their rapid response to deposited fresh phytodetritus demonstrate the importance of foraminifera in short-term carbon cycling under oxygen-depleted conditions. We propose that foraminifera at the studied site benefit from unique adaptations in their metabolisms to nearly anoxic conditions as well as from the exclusion of macrofauna and the resulting relaxation of competition for food and low predation pressure.

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