North and South Aeagen Sea

Sedimentation flux of biological detritus in the water column; Sedimentation flux of identified biota expressed as carbon in the water column; Sedimentation flux of pigments in the water column

Sediment traps

Phytoplankton sedimentation was determined in depths 500 and 1213 m, using a sediment trap mooring. Subsamples for microscopic examination were taken and fixed with formaldehyde (ca. 2% final concentration). Phytoplankton was counted according to a combination of methods described in Sournia (1978). A standard light microscope, furnished with a counting stage (Semina 1978) was used. The whole sample was gently mixed. Counting of the pico- and most abundant nanoplankton algae (< 2 micro m and 2 - 20 micro m, respectively), was carried out in the Fuchs-Rosenthal counting chamber with magnification of 400 x. After the smaller phytoplankton was enumerated, samples were allowed to settle for a week, and then slowly decanted through a glass tube covered with two layers fine-mesh nylon gauze to a 5-10 ml concentrated sample. After gentle mixing, a sub-sample was transferred to a 0.05 ml. chamber. Cells were counted under magnification of 200 x. In order to count rare (usually larger) forms, the whole sample was reduced to 1 ml by settling to a 1.0 ml chamber. As this was rather thick, only a low power objective (100 x magnification) could be used. Biovolumes of individual cells were calculated from linear dimensions of measured cells applied to appropriate stereometric formulae (Smayda 1978). The carbon content of the algae (PPC) was calculated based on average volume of the different species and according to Strathmann (1967).Faecal pellet sedimentation was determined in depths of 500 and 1213 m, using a sediment trap mooring. Subsamples for microscopic examination were taken and fixed with glutaraldehyde (ca. 4% final concentration). Sedimented faecal pellets (FP) were enumerated under an inverse microscope according to Utermohl (1958). The FP were classified according to their shape as cylindrical, filiform and oval. Some of these categories were then separated into size classes according to the width and length of the FP. The faecal pellet volume (FPV) was calculated using appropriate stereometrical configurations according to Edler (1979). To calculate the faecal pellet carbon (FPC) content a factor of 0.0694 mg C mm-3 obtained by Gonzalez and Smetacek (1994) was used The data shown here are presented in terms of carbon (mg C m-2 d-1)

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