TY - JOUR
T1 - Comparison of isotopic composition of planktonic foraminifera in plankton tows, sediment traps and sediments
AU - Erez, Jonathan
AU - Honjo, Susumu
PY - 1981/3
Y1 - 1981/3
N2 - Planktonic foraminifera from plankton tows, sediment traps and sediments in the central North Atlantic were studied in order to understand what determines their oxygen and carbon isotope composition. A clear separation of species and genera on a δ18O vs. δ13C plot for all samples suggests that their isotopic composition is controlled to a certain degree by biological factors. Within a species population, the globorotaliids show a positive linear correlation between δ18O and δ13C, while the shallow-dwelling spinose species (mostly Globigerinoides species) do not show a definite trend. The latter species, when collected in plankton tows, often show slight negative deviations from isotopic equilibrium with respect to oxygen. All species deviate from carbon isotope equilibrium by -1.5 to -6‰. These deviations from equilibrium are probably caused by incorporation of isotopically light metabolic CO2 into the skeleton, which is enhanced by the activity of symbiotic algae. During their ontogeny the average weight per individual of most species increases which indicates that calcification continues to a depth of about 100 m. This additional skeleton (roughly 50% by weight) is isotopically heavier because temperatures are lower and photosynthesis of symbiotic algae stops below the photic zone. Therefore, the skeleton of foraminifera collected in sediment traps below 400 m has an overall oxygen isotope composition that seems to be in equilibrium for CaCO3 deposited in the upper 100 m.
AB - Planktonic foraminifera from plankton tows, sediment traps and sediments in the central North Atlantic were studied in order to understand what determines their oxygen and carbon isotope composition. A clear separation of species and genera on a δ18O vs. δ13C plot for all samples suggests that their isotopic composition is controlled to a certain degree by biological factors. Within a species population, the globorotaliids show a positive linear correlation between δ18O and δ13C, while the shallow-dwelling spinose species (mostly Globigerinoides species) do not show a definite trend. The latter species, when collected in plankton tows, often show slight negative deviations from isotopic equilibrium with respect to oxygen. All species deviate from carbon isotope equilibrium by -1.5 to -6‰. These deviations from equilibrium are probably caused by incorporation of isotopically light metabolic CO2 into the skeleton, which is enhanced by the activity of symbiotic algae. During their ontogeny the average weight per individual of most species increases which indicates that calcification continues to a depth of about 100 m. This additional skeleton (roughly 50% by weight) is isotopically heavier because temperatures are lower and photosynthesis of symbiotic algae stops below the photic zone. Therefore, the skeleton of foraminifera collected in sediment traps below 400 m has an overall oxygen isotope composition that seems to be in equilibrium for CaCO3 deposited in the upper 100 m.
UR - http://www.scopus.com/inward/record.url?scp=0019369270&partnerID=8YFLogxK
U2 - 10.1016/0031-0182(81)90035-3
DO - 10.1016/0031-0182(81)90035-3
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AN - SCOPUS:0019369270
SN - 0031-0182
VL - 33
SP - 129
EP - 156
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
IS - 1-3
ER -