Experiments conducted with natural mixed populations of 800 and 1,800 tubificids m−2 in sediment from Messalonskee Lake, Maine, showed average sediment transport by alimentation at 10°C 2–3 times greater than highest rates previously reported. More than 95% of feeding on introduced pollen was at depths above 7 cm, with greatest feeding at 3–4 cm. Small amounts of pollen were raised to the surface from as deep as 15 cm. Downward transport was 14 and 19% of upward. Small pollen grains (< 40 µ) were fed upon and displaced at higher rates than large grains. Organic matter was less in the surface layer of feces than in sediment from feeding depths and in surface sediment where no worms were present. A mathematical model was used to appraise the stratigraphic effects of the worms by deriving age‐frequency composition of sediment at various depths.