The epibenthic sled was designed by Dr. Robert Hessler of Scripps Institute of Oceanography Howard Sanders and George R. Hampson of the Woods Hole Oceanographic Institution (Hessler, Sanders 1966). The net (1mm mesh) was specially designed plankton net made by William Shoeder's (WHOI) daughter, Mrs. Ernest Case of N.J. She designed the nets for both the small (4ft. long) and the larger epibenthic sleds (7ft. long).
The larger 7-ft. sled was primarily designed for deep-sea sampling. For the WHOI Sanders/Hessler project, we towed it at depths exceeding 5000 meters. The purpose was to collect rare deep-sea animals which otherwise would be impossible to capture with grab samplers or box cores. However, the epibenthic sled was considered to be less than quantitative. Distances covered over the bottom can be estimated from the ship's log to get an estimate of the area covered, however the sled was never as accurate as the box corer for density determinations of the macrofauna.
How It Works
A semi-quantitative bottom-sampling device is designed to trawl just above the bottom at the sediment water interface (the epibenthic zone). The sled occasionally (inadvertently) digs into the bottom, so an infaunal sample is also collected. The sled is fitted with a 1mm mesh net. The end of the sled is fitted with an extended removable cod end, which served to provide the sled with a protected area where the animals were not subjected to abrasion. Some cod ends were made with 0.5mm mesh to retain smaller organisms.
A "front door" closing device was incorporated to retain the collected sample inside the dredge to prevent washing while the dredge is being brought to the surface. This spring-driven closing of the trawl was activated by a timing devise designed by Benthos of North Falmouth.
The smaller (4 ft. long) sled has been used successfully for many years to collect benthic organisms from local coastal waters.
Some descriptions provided by George R. Hampson.
Last updated: March 1, 2007