The origin of transparent exopolymer particles (TEP) and their role in thesedimentation of particulate matter

Seasonal changes in the concentration of suspended transparent exopolymer p articles (TEP) and flux rates of TEP and other particles at 500 m were meas ured at 2-week intervals at a station in the Santa Barbara Channel between May 1995 and June 1997 in order to investigate the hypothesis that the pres ence of TEP is necessary for the aggregation and subsequent sedimentation o f particles from the pelagic zone. During the 2-year period phytoplankton a ppeared to be the most significant source of TEP. However, in association w ith phytoplankton, the concentration of TEP was also positively affected by bacteria abundance. Possibly bacteria enhance the production of TEP by phy toplankton. The presence of TEP was necessary for the sedimentation of diat oms. However, only 67% of the peaks in particulate organic carbon flux corr esponded to peaks in TEP flux. Lithogenic silica sedimented only when scave nged by marine snow; either by TEP-rich diatom aggregates or by zooplankton -derived snow (larvacean houses). TEP were not involved in the sedimentatio n of foraminifera. Although sedimentation was the dominant loss processes o f TEP out of the euphotic zone, other loss process must have been important at greater depth, as only a small fraction of the standing stock of TEP ar rived at 500 m. (C) 2001 Elsevier Science Ltd. All rights reserved.