As many reading this will know, rapid warming is causing higher water temperatures and a reduction of the ice cover in the Arctic. These changes will almost certainly provoke severe perturbations of the marine food chain. Over the past decade, a geographical displacement of marine mammals has been observed, coinciding with a decline of their benthic preys. The benthic fauna, which is composed of organisms closely related to the sea floor, are a major component of the Arctic marine ecosystem. They participate in the transfer of material and energy through the system and are an important link between primary producers and higher trophic levels. It is thus essential to establish benchmarks in biodiversity at key locations in the Canadian Arctic. However, the existing datasets on the distribution and biodiversity of benthic organisms are restricted to a few specific regions. The aim of the current fieldwork is to describe and compare the biodiversity and secondary productivity of benthic communities in areas of enhanced and reduced (“hot spots” and “cold spots”) productivity in the Canadian Arctic.

A custom-built Agassiz trawl was tested for the first time on board to collect benthic specimens.

The trawling operation consists in deploying the instrument on the sea bed for 5 to 10 minutes for each sampling session. Since the beginning of Leg 3, Agassiz trawls has performed at 8 stations with a range of locations including Baffin Bay, the eastern edge of Viscount Melville Sound, McClintock Strait, Dease Strait and the Beaufort Sea. Catches consisted mainly of brittle stars, worms, fishes, molluscs and amphipods.

In Viscount Melville Sound, a spectacular sea spider was collected, which is only distributed in Arctic.

We also collected an octopus, some big isopods and sea stars.

Box cores were also performed to determine the biodiversity of benthic communities.

Following retrievals, sediment samples were sieved through a 500 m mesh size and preserved for further identification in the laboratory.