RRS James Clark Ross JR16006: 30 June-8 Aug 2017, the Changing Arctic Ocean Cruise JR16006

The Arctic environment is changing, rapidly. Sea ice concentrations and ice extent are decreasing, the ocean and atmosphere are warming, fresh water discharges are increasing and stratification, mixing and circulation regimes are altering. All these changes impact the Arctic Oceans ecosystem, from the sea surface to the sea floor. For example, longer and more expansive open water periods influence the timing and longevity of phytoplankton blooms which are important for sustaining life at all trophic levels, from tiny zooplankton in the water column and microscopic benthic fauna, right up to the whales and seals at the top of the food chain. Changes in the light and nutrient regimes have consequences for the amount and quality of particulate and dissolved organic matter, the cycling of nutrients in the water and sediments, and consequently the biodiversity of life that can be supported. The migration and grazing of zooplankton, behaviours that transfer huge quantities of carbon into the ocean interior, may also be affected. In 2017 the Natural Environment Research Council (NERC) started an investment of £16 million in its 5-year Changing Arctic Ocean Programme (www.changing-arctic-ocean.ac.uk). The overarching aim of the programme is to better understand and quantify the impacts of climate change on Arctic ecosystems. The findings will ultimately inform our conservation and management strategies of polar regions. Four large projects were initially funded: ARISE (led by Claire Mahaffey, Uni. Liverpool), Arctic PRIZE (led by Finlo Cottier, SAMS), ChAOS (led by Christian März, Uni. Leeds) and DIAPOD (led by David Pond, SAMS). JR16006 was the first in a series of Changing Arctic Ocean cruises to the Barents Sea in support of all four projects. The overarching aim of the cruise was to collect a suite of pelagic and benthic samples across water mass (Atlantic to Arctic) and sea-ice gradients to enable: • Determination of dissolved and particulate organic material and inorganic nutrients • Estimation of water column primary production, phytoplankton community composition, photo-physiology and biomass • Foodweb tracer analysis using stable isotopes techniques • A mapping of the baseline ‘isoscape’ • Determination of the total zooplankton community and lipid content • Determination of the sediment and pore water geochemistry - amount of organic material and its degradation and interactions with biological processes (e.g., bioturbation, microbial community structures) • Determination of the structure, function (e.g. nitrogen cycling, bioturbation), diversity and reproductive state of benthic communities (from epifauna to meiofauna) • Determination of water column and seabed microbial community and diversity All of the 18 stations (B1- B18) identified pre-cruise were sampled by the ARISE, PRIZE and DIAPOD projects. The ChAOS project conducted extensive sediment and benthic fauna sampling at 6 of these stations (B3, B13-B17)