Bottom Grabbing

When sea ice or rugged terrain make it too risky to deploy the epibenthic sledge (EBS), we rely on a more compact and ice-friendly tool: the Smith McIntyre Grab.

If you’ve ever played the claw game at an arcade, you already have the basic idea. The grab is lowered to the seafloor with its jaws open. When it makes contact with the bottom, the jaws snap shut, capturing a box-shaped sample of sediment along with all the small animals living in and on it. We then bring the grab back to the surface and carefully sieve and preserve the sample for further study.

While the EBS excels at sampling fauna living on or very near the surface of the sea floor, the Smith McIntyre Grab is ideal for collecting more quantitative, sediment-based samples—especially in spots where the EBS can’t go. It’s also a safer option in icy conditions, where a stray chunk of sea ice could damage the EBS on its way up or down. Today we used the grab to sample the top of a seamount. It returned a beautiful sample with lots of diversity including some burrowing animals not normally collected with the EBS.

We checked out the original paper describing the design of the grab and were amused to see that the version on the NBP is virtually identical to the original design from 1954!

These grab samples are rich with hidden biodiversity—tiny crustaceans, worms, mollusks, and other invertebrates that help us understand the complexity of Antarctic benthic ecosystems. Stay tuned as we dig deeper (literally and figuratively) into what we find!

Dr. Kevin Kocot
University of Alabama