Seasonality and Interaction of Biogenic and Lithogenic Particulate Flux at the Panama Basin

TLDR

Year‑long sediment traps were deployed at 890, 2590, and 3560 m in the Panama Basin to measure particulate flux. Particulate fluxes were seasonally pulsed, with two organic spikes—an upwelling‑driven high‑productivity period in February–March and a coccolithophorid bloom in June–July—delivering ~25 g m⁻² of coccoliths at 3860 m, while lithogenic flux rose with depth and tracked surface production and currents, suggesting efficient scavenging of clays by sinking organic aggregates.

Abstract

Time-series sediment traps were deployed for an entire year at three depths (890, 2590, and 3560 meters) at a deepwater station (3860 meters) in the Panama Basin. The amount of horizontal and lithogenic particulate material arriving at the three depths was seasonally pulsed and directly reflected changes in surface primary production. Two spikes of organic flux were simultaneously recorded at all three depths: (i) a period of high productivity during regional upwelling in February through March and (ii) an unusual bloom of a single species of coccolithophorid during June through July. This latter spike delivered approximately 25 grams of coccolith per square meter of area at a depth of 3860 meters during less than 60 days. The flux of lithogenic particles increased with increasing depth and was seasonally correlated to surface production and current direction, and not to the detritus discharged in river flow. The data suggest that suspended clays are efficiently scavenged from the water column by rapidly sinking organic aggregates.