The previous ChAOS cruise en route to the Barents Sea

ChAOS cruise sets sail to study the Arctic Ocean

Images by Johan Faust 

PML scientists today travel to the Arctic to study how environmental change is affecting the hidden world beneath the ice.

They will be on the third Changing Arctic Ocean (CAO) research cruise of the summer, venturing into the Arctic Circle and the Barents Sea aboard the RRS James Clark Ross.

Warming in the Arctic region is increasing faster than elsewhere on the planet, and this is having an unprecedented impact on how the Arctic ecosystem operates. One of the key drivers of change is the retreat of sea ice in the Arctic Ocean, which plays a key role in the supply of light and the delivery nutrients, and which in turn controls biological productivity. The impacts of retreating sea ice affect the whole Arctic Ocean, and this includes the sea floor which depends on the downward drift of food from the surface to sustain animals living at the bottom. The quantity and nutritional quality of this food supply varies greatly depending on whether it grows on the underside of the ice as ice algae or grows freely in open water as phytoplankton. This year has seen record lows of sea ice, with far less ice sea ice in the Barents Sea this month compared to the same time last year. The team heading to the Arctic today, including PML scientists alongside researchers from several UK and European research institutes, will investigate how the rapid retreat of sea ice affects the processes happening on the sea floor.

Scientists from the programme’s ChAOS project (Changing Arctic Ocean Seafloor) will spend a month at sea to collect water, sediments, microbes and animals from the bottom of the Barents Sea. They have two critical areas of interest. The first is the Polar Front, where the Atlantic enters the Arctic Ocean and brings in water with different nutrient concentrations, salinity and temperature. The second is the edge of the sea ice, where marine ecosystems go from complete darkness during full winter sea ice cover to experiencing light again as the sea ice recedes during the transition to summer. The presence of light and nutrients is essential for the microbes and animals at the bottom of the Barents Sea to grow.

The team will revisit the same locations as they sampled on their first trip to the Barents Sea in July 2017, enabling the comparison of results from one year to the next. This will allow us to see how quickly the Arctic seafloor responds to changes in sea ice conditions. The scientists leading this research will send various pieces of scientific equipment into the depths to collect different kinds of samples, from huge bottles attached to frames for seawater, to steel boxes for collecting sediment, and plastic tubes that will core the top metre of the seafloor.

Prof. Steve Widdicombe, Head of Science for the Marine Ecology and Biodiversity group, is one of the Principal Scientists on the ChAOS project: “The Arctic Ocean is one of the most rapidly changing environments on our planet and, as marine scientists, it is certainly one of the most exciting and important environments for us to study. On last year’s expedition we encountered a lot of sea ice in the Barents Sea - at many of our sampling stations we had to break open this ice so we could collect our samples. This year satellite images have shown us there is almost no ice in the Barents Sea and ocean conditions are very different to last year. Whilst these dramatic differences in ice cover will give us a fantastic opportunity to study the effects of sea ice loss on the biodiversity and functioning of the seabed, I do hope this year proves to be an unusual event and does not signal the beginnings of regular ice-free summers in the Barents Sea.”

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