LUNAR-INFLUENCED CARBONATE FLUX OF THE PLANKTIC FORAMINIFER GLOBIGERINOIDES-SACCULIFER (BRADY) FROM THE CENTRAL RED-SEA

Two phenomena control the rate of sedimentation of planktic foraminife rs: (1) changes in the population structure with time; and (2) size-de pendent settling velocities of empty shells. As a result, the total fl ux and the flux per-size-fraction change significantly during a reprod uctive cycle. This implies that timing and duration of collection of t rap devices are important parameters for interpreting sediment trap-co llected samples. Using data on the distribution and abundance of livin g Globigerinoides sacculifer (Brady) from the central Red Sea, a shell flux was modelled. The simulations demonstrate that the sedimentation pattern oscillates on a lunar basis. The foremost result of this stud y is that the timing of trap deployment within the lunar cycle does no t influence the collection if the deployment time of the trap is equal to or a multiple of the reproductive cycle. The effect of two variabl es on the daily calcite flux was investigated: (1) the reproduction ra te; and (2) the length of the reproductive period. A decrease in the r eproduction rate shifts the calcite flux maximum from full moon to new moon. A short reproduction period intensifies the full moon flux maxi mum, especially at high reproduction rates. The total monthly calcite flux, however, is independent of these variables. An estimate for the carbonate flux in the Red Sea due to G. sacculifer alone is 1 g m-2 ye ar-1.