Foraminiferal Population Dynamics And Stable Carbon Isotopes

Most planktic foraminifera live within the photic zone and exhibit a life style tied to the lunar cycle. They migrate between the reproductive depth (thermocline and/or the chlorophyll maximum) and the uppermost part of the photic zone. This ontogenetic migration pattern sets the initial δ13C of the foraminiferal shell. On top of that, biological fractionation processes (vital effects) modify the signal. These processes include photosynthetic activity of the symbionts and respiration of the host/symbiont complex. Globigerinoides sacculifer (Brady) was chosen to model ontogenetic changes in the δ13C of the shell as a function of depth migration with and without vital effects.