Benthic Grabs

Ocean Ecology has two different sizes of grabs for benthic grab sampling:

• a Petit Ponar grab which can sample between 1.5 and 3 L of sediment from substrates such as sand, gravel, consolidated marl or clay (see photo below).
• a Standard Ponar grab which can sample up to 8.2 L of sediment from hard bottoms such as sand, gravel, consolidated marl or clay (see photo below).

For size comparison, both the Petit and Standard Ponar grabs are shown below. Both grabs are equipped with sliders. Sliders allow easy access to undisturbed surface sediments as is often required by many chemical analyses.

The operation of the sliders on the Standard Ponar grab is shown in the photo below. These sliders were recently installed after some adventures with attempting to get sticky clay to come out of the grab right-side-up for surface sampling!

Both core and grab sampling are done using a hydraulically operated A-frame and winch from the stern of the Moody Blue.

Sieving, sorting, identification, and diversity analysis of benthic macroinvertebrates in a sediment sample can be carried out.