Sedimentation of Planktonic Foraminifera: Seasonal Changes in Species Flux in the Panama Basin

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Abstract
Seasonal changes in the flux of individual planktonic foraminiferal species to the sea floor were studied in the Panama Basin using material collected in 1 yr by an array of automated sediment traps. The traps were placed at 3 depths in the water column, at 890, 2590 and 3560 m, with each designed to collect a time-series of 6 consecutive 2 mo. samples. In general, 2 basic seasonal flux patterns were recognized. One group of species is marked by a distinct maximum in flux during Feb. and March, in association with the period of most extensive upwelling in the Panama Basin. The species that display this flux pattern are typically conspinose and live predominantly at or below the thermocline, then migrate toward the surface as upwelling intensities. The 2nd group displays more of a bimodal seasonal flux pattern, with maximum values during June through Aug. and a secondary peak in Feb. and March. This group consists primarily of the spinose species that live above the thermocline in the mixed zone and possess symbiotic zooxanthellae. The increase in flux of these species during the summer occurs when the mixed zone is relatively deep and is associated with a phytoplankton bloom; the winter increase occurs during the upwelling of nutrient-rich waters.