Dimensions and sinking speeds of tropical radiolarian skeletons from the parflux sediment traps : technical report

Abstract

Length, width and projected area (58 species) and weight (53 species) of radiolarian. skeletons, mainly from the Panama Basin PARFLUX sediment trap (5°21.8'N, 82°01.4'W) samples, were measured. Volume and density contrast were computed. The measured mean weight values for the examined species range from 0.05 pg/shell to 24 μg/shell. The weight is best correlated with projected area among the studied size dimensions of Radiolaria as a whole group. The density contrast of the radiolarian skeletons, relative to seawater, generally falls between 0.01 and 0.5 g/cm3 and appear to be constant with an order of magnitude increase of the shell diameter. The sinking speeds of specimens of 55 radiolarian species measured in 3, 10 and 20°C seawater range from 13 to 416 m/day. Despite the wide variety of morphology between the species, the sinking speed is best correlated with weight/shell with reasonably small deviations from a regression line. Using the sinking speeds residence times of the 55 species in the 5 Krn pelagic water column range from 2 weeks to 14 months.