Estimation of the catchment area of a sediment trap by means of current meters and foraminiferal tests

Between June 1989 and July 1990 a mooring equipped with four current meters and one sediment trap was deployed in the Fram Strait (79°N). From the material collected by the sediment trap two species of planktic foraminifera (Turborotalita quinqueloba and Neogloboquadrina pachyderma) were used to estimate the catchment area of the sediment trap. For each species and size class the individual sinking velocity was used to determine the residence time in the water column. The residence time is the major factor that determines the drift of the tests. Using current-meter data trajectories were calculated to estimate the catchment area and the area of sedimentation. The maximum distance the smallest tests have been transported, while sinking from the surface (∼100 m) to the sediment trap (1125 m), is approximately 275 km, with maximum trajectory lengths of up to 300 km. Depending mainly on the grain size of the tests, the distances and trajectories have means lying between 25 and 50 km for N. pachyderma and 50 and 100 km for T. quinqueloba, respectively. Considering the whole sampling period, the estimated catchment areas are 23,900 km2 for all N. pachyderma tests and 33,300 km2 for all T. quinqueloba tests, respectively. The respective areas of sedimentation are estimated to range from 3400 km2 to 3500 km2.