On: The Benthic Sled - our PONAR dredge collections
allow us to determine the number of organisms living in the
sediment, but only yield a few dozen animals per sample. Our
scientists wish to collect Diporeia and determine their content
of lipids (a measure of health and value as a food for fish),
carbon and stable isotopes (an alternative measure of biomass
and indicator of their food sources) and synthetic organic
chemicals (a measure of contamination). For this we need the
benthic sled. This huge net in a sled-like frame is towed
at depth behind the boat for about ten minutes and brought
to the surface and harvested. Literally kilograms of Diporeia
and Mysis are collected. The samples must then be ‘picked'
in the laboratory, separating the animals from the detritus
and processing them for storage and later analysis.