Benthic Studies – Boxcores, Brittlestars and Being Called Dirty
Heike Link, University of Quebec at Rimouski

It’s Saturday night, 8 pm – and my face is feeling hot from a nice sunbath on the helicopter deck. Tonight the galley had prepared a BBQ for the crew – and as the weather is spoiling us with sunshine and no winds on this day, it has definitely been one of the very special ones, that make me appreciate how lucky I am to be working in the Arctic.
I have just started my PhD in oceanography at the University of Quebec at Rimouski this March. I am working on benthic ecology, i.e. all the living things we find on the seafloor that are bigger than 0.5 mm, and about what role they play in the Arctic Ocean ecosystem.
Lots of discussions are dealing with the influence of climate change and the reducing ice cover on the Arctic Ocean, particularly on its primary production (algal blooms), and the associated zooplankton. Unfortunately, a lot of people tend to overlook the role of the benthic part in ecosystems:
Many of the animals living all the way down on the bottom of the Arctic Ocean feed on dead algae and phytoplankton, which sink down from the water column. As the animals down there consume food, they will also produce nutrients, which will diffuse back to the water column and be a part of the source for the next plankton bloom. And as the equilibrium between zooplankton and phytoplankton will change with the environmental changes, there will also be less food available for the benthos – which in turn will influence the amount of nutrients produced at the seafloor.
To understand the relationship between primary production and benthic activity, our team is measuring the consumption of oxygen and the changes of nutrients by benthic communities before and after an algal bloom.
We use a box corer to bring up a 50 x 50 x 50 cm chunk of sediment from a depth of 200 m or more underneath us. Then we incubate sediment cores of 10 cm in diameter for about 2 days to measure the oxygen and nutrient changes in the water column covering them (Fig. 1).

Fig. 1: Left - The box corer with a successful sample. Right - The incubation core setup (Photos: Haakon Hop).
To gain a better knowledge on how much and which kind life is flourishing on a dark and cold place as the Arctic seafloor, we also use an Agassiz trawl (a net dragged on the sediment). And I promise, you would be as fascinated as I am every time, to see how many crazy and beautiful animals we catch down there (Fig. 2).

Fig. 2: Catches from the Agassiz sled. Upper left – brittlestars (Photo: Haakon Hop). Upper middle – Mylène and a full Agassiz net (Photo: Lucy Calderon Pinera). Upper right – an Ampharetid polychaet worm (Photo: Mylène Bourque). Lower left: starfish Ctenodiscus crispatus (Photo: Mylène Bourque). Lower right: the Agassiz sled and the crab Hyas coarctatus (Photo: Myriam Paquet-Gauthier).
Sadly, we tend to have a dirty reputation – not for observing the little creatures, but rather for all the sediments, that we have to clean off the ship once we’re done. But at the same time, the nice brittlestars we catch seem to be too interesting for our spectators, than to be scared away by the muddy boxcore.
Want to know more? Check out Mylène’s dispatch from leg 3!