Bag of mud

The Van Veen grab with a full load of sediment

"I got a jar of dirt, I got a jar of dirt, and guess what's inside it?"

- the movie Pirates of the Caribbean: Dead Man's Chest

Sam stepped over the threshold into the heated cabin of the boat. In one hand, he held a trash bag heavy-laden with seafloor sediment. "Alright, let's put this trash bag of mud in the bathroom!"

I couldn't help but giggle. How many times in a person's life do they get to speak that sentence? Not many, I'm sure.

Xiaoshou and Hongju emptying the grab into a trash bag

Xiaoshou and Hongju sieving the sediment samples

One of our main objectives for this research trip is to sample the benthic community - all the animals that live on the seafloor in the fjord just outside Ny-Ålesund. To do that, we're using a Van Veen grab, which is a common tool for marine biology. The grab consists of two curved blades that close automatically to collect sediment. We prop the blades open and lower the grab to the seafloor on a winch cable. When the grab reaches the seafloor, it sinks into the sediment a little bit. Then when we pull it back up, the blades close and trap the sediment inside. Van Veen grabs are nice to use because they are light and simple. Plus, each grab collects sediment from a known surface area of the seafloor, so our samples are standardized. 

Once we get the grab back on the deck of the boat, we have to get the sediment out. I had packed a shallow tray to use as a sediment receptacle, but we wanted to collect 4 grabs from each station and had only one tray. We needed a place to store the sediment we had collected until we got back to the lab. We settled on using trash bags as tray liners and sealing them off with duct tape. Once filled, the bags were stored in Teisten's bathroom, because it was warm enough in there to keep the samples from freezing and too cold for us to use the plumbing anyway. 

One of the sediment samples after sieving. Lots of worms!

Back in the lab, we had to sieve the sediment to reveal the animals inside. Marine sediments are filled with all kinds of organisms that live in the small, water-filled spaces between the grains. There are worms and clams galore! Some animals are large enough to see with your eye - we actually had a really large snail - but most of them require a microscope. Xiaoshou specializes in a group of worms called nematodes that are so small and so clear, you have to dye them red to see them in the sample and use a microscope to sort them. He sub-sampled 40 mL of sediment from each grab to analyze the nematode community, and he expects to find hundreds of specimens in that small volume.

We're all very excited to see what the sediment samples reveal!