Standing stocks and carbon isotopes of live benthic foraminifera from the South Atlantic

• Main Authors: Mackensen, Andreas, Licari, Laetitia
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2004
• Subjects: ANT-IX/4; ANT-VIII/3; Atlantic Ridge; AWI_Paleo; GeoB3703-4; GeoB3705-2; GeoB3706-3; GeoB3708-1; GeoB3711-1; GeoB3712-1; GeoB3713-1; GeoB3715-1; GeoB3725-1; GeoB4904-7; GeoB4906-5; GeoB4909-4; GeoB4913-4; GeoB4915-3; GeoB4916-4; GeoB4917-5; Indian-Antarctic Ridge; M34/2; M41/1; Meteor (1986); MUC; MultiCorer; Northern Cape Basin; northern Congo fan; off Angola; off Gabun; off northern Gabun; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS16; PS16/316; PS16/342; PS1771-4; PS1777-7; PS18; PS18/250; PS18/251; PS18/252; PS18/253; PS18/254; PS18/255; PS18/256; PS2092-1; PS2093-1; PS2094-1; PS2095-1; Antarc*; Antarctic; Antarctica; South Atlantic Ocean; Southern Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.728233; https://doi.org/10.1594/PANGAEA.728233

Live (Rose Bengal stained) and dead benthic foraminifera of surface and subsurface sediments from 25 stations in the eastern South Atlantic Ocean and the Atlantic sector of the Southern Ocean were analyzed to decipher a potential influence of seasonally and spatially varying high primary productivity on the stable carbon isotopic composition of foraminiferal tests. Therefore, stations were chosen so that productivity strongly varied, whereas conservative water mass properties changed only little. To define the stable carbon isotopic composition of dissolved inorganic carbon (d13CDIC) in ambient water masses, we compiled new and previously published d13CDIC data in a section running from Antarctica through Agulhas, Cape and Angola Basins, via the Guinea Abyssal Plain to the Equator. We found that intraspecific d13C variability of all species at a single site is constantly low throughout their distribution within the sediments, i.e. species specific and site dependent mean values calculated from all subbottom depths on average only varied by +/-0.09 per mil. This is important because it makes the stable carbon isotopic signal of species independent of the particular microhabitat of each single specimen measured and thus more constant and reliable than has been previously assumed. So-called vital and/or microhabitat effects were further quantified: (1) d13C values of endobenthic Globobulimina affinis, Fursenkoina mexicana, and Bulimina mexicana consistently are by between -1.5 and -1.0 per mil VPDB more depleted than d13C values of preferentially epibenthic Fontbotia wuellerstorfi, Cibicidoides pachyderma, and Lobatula lobatula. (2) In contrast to the Antarctic Polar Front region, at all stations except one on the African continental slope Fontbotia wuellerstorfi records bottom water d13CDIC values without significant offset, whereas L. lobatula and C. pachyderma values deviate from bottom water values by about -0.4 per mil and -0.6 per mil, respectively. This adds to the growing amount of data on contrasting ...