A sedimentation trap for use just above the deep-sea floor was free-fallen to a depth of
2050 m in the Tongue of the Ocean canyon on January 3, 1974. On March 6, it was successfully
recovered with the assistance of D.S.R.V. Alvin. The trap has a base 1 m square and a
height of 30 cm. At the trap bottom are filters to retain falling particles. Two spring-powered
sliding doors, each 1 m x 0.5 m, are used to close off the lower 2 cm of the trap during
ascent to prevent disturbance of the particles collected on the filters.
Total carbon on the filters as determined by high temperature combustion averaged 2301
mgC/m2 or an average on a daily basis of 36.5 mgC/m2. Similar filter aliquots were treated
with cold phosphoric acid to eliminate the inorganic fraction. The resulting carbon values
(X =: 5.7 mgC/m2/day) suggest 14% of the total carbon reaching the sea floor at 2000 m in
this area is organic in origin. Fecal material is one readily identifiable component of the material
contributing to the organic fraction. Counts of fecal pellets resulted in an estimate of an
average of ~650 pellets/m2/day. Average pellet length was 241 ?m and diameter was 109
?m. In laboratory experiments the pellets sank at rates varying from 50 m/day to 941 m/day
(X at 5°C =159 m/day).
Comparison of the sedimentation trap estimates of organic carbon input to the sea floor in
this area with benthic energy requirements indicates that rapidly sinking small particulate matter
could supply approximately 14% of the metabolic requirements of the benthos.