7 August 2019 Mud From the Bottom of the Bering Sea

Journal

Before we get into today's journal entry, I want to remind you all that my PolarConnect event is scheduled for August 20th at 5pm EST. This is a live stream with myself, Dr. Lee Cooper, Dr. Jackie Grebmeier, and others to talk about the polar research happening on the Healy. Please sign up for this free event here.

Piper Bartlett-Browne uses a hose to remove mud from the grabs to expose the living and dead organisms.

Over the last few days, I have been welcomed into the world of polar research. The benthic team, led by Jackie Grebmeier and Lee Cooper, is my main assignment on the ship. One of the samples that this team collects is mud and benthic organisms (animals that live on the ocean floor) using a device called the Van Veen Grab. This instrument was invented by Johan van Veen, a Dutch engineer, in 1933 to collect sediments. When the Van Veen is deployed, it grabs 0.1 square meters of mud off the bottom and brings it back to the surface for us to look at.

The Van Veen grab being prepared for deployment on the deck of the Healy.

The Van Veen grab is lowered into the ocean by Coast Guard crew from the back deck of the Healy.

The Van Veen grab being lifted back onto the Healy after taking a benthic sample.

Once the Van Veen grab is on deck, the Coast Guard personnel on the deck open it up and a member of the benthic team empties out the mud into a bucket using a hose and a spoon. In some of the grabs that are recovered, a trap door on the top of the grab is opened first and samples of the mud from the very surface are put into a bag and frozen to be taken back to the lab in Maryland where they will be tested for among other things, organic carbon content. The more carbon in the sample, the higher the productivity and, ultimately, the biomass. This means that samples taken from carbon-rich areas are healthy ecosystems that are important to the food web.

Caitlin Meadows and members of the Coast Guard empty the mud from the grab with a hose and spoon.

Once the mud samples are collected, the mud is poured from a bucket into a 1 mm sieve where members of the benthic team use a hose to gently remove mud from the dead and living specimens in the mud. Different species of worms, bivalves, and many other taxonomic groups are represented in the Bering Sea benthic community. All the mud goes through the sieve and leaves a multitude of organisms that are preserved and taken back to the lab where they will be identified to determine biodiversity and biomass.

The mud from the grab being poured into a sieve for processing.

The contents of the sieve box as the mud is being washed from the sample.

Dr. Grebmeier and Dr. Cooper have been sampling the sediments in the Bering and Chukchi Seas for almost three decades and have seen how the benthic communities have changed over time. With the loss of sea ice and rising ocean temperatures due to climate change, they are particularly interested to see how this effects these organisms. The data collected by the Van Veen grabs can help them to get a better picture of what is happening on the bottom of the Arctic.