GO-WEST, RV Sikuliak, Beaufort Sea

Sea-ice association of polar cod and its prey in the western Arctic Ocean (GO-WEST)

Principal investigator: Dr. Hauke Flores, Alfred Wegener Institut, Germany

Proposal Partners: Dr. Franz Mueter, University of Alaska Fairbanks, USA
Prof. Dr.Filip Volckaert, Catholic University of Leuven (KUL), Belgium
Ms. Fokje Schaafsma, Wageningen Marine Research (WMR), Netherlands

Research Icebreaker: RV Sikuliaq (UAF-CFOS, USA)

Schedule: November 2019

Facebook or blog links: https://www.facebook.com/rvsikuliaq/

Abstract: Polar cod (Boreogadus saida) is a key fish species in Arctic marine ecosystems, because many Arctic birds and seals feed on this fish. However, polar cod may be particularly susceptible to sea-ice decline, because the young fish need sea ice as a shelter and a feeding ground. It has been proposed that parts of the population are entrained with the growing sea ice in autumn, but how this happens and what proportion of the population becomes stays with the sea ice is not known. Scientific studies using biomarkers have shown that young polar cod depend very much on biochemical compounds originating from algae growing within the sea ice (ice algae). The entrainment of young polar cod to the sea ice habitat during autumn may be a critical process in a sea-ice associated survival strategy of this species that is not at all understood. The overall goal of the proposed sampling is to test the hypothesis that many young polar cod in the Chukchi and Beaufort Seas are entrained into the sea-ice habitat during autumn, and hence sea-ice association is an important survival strategy with positive effects for the adult population. Sampling of polar cod and its prey in the ice-water interface layer combined with high resolution profiles of sea-ice properties will be combined with echosounder profiles to examine direct and indirect dependencies of polar cod populations on sea ice.

Summary of the Go-West Cruise

ARICE cruise acronym: Go-West

Full title: Sea-ice association of polar cod and its prey in the western Arctic Ocean

ARICE vessel involved: RV Sikuliaq

Implementation: together with the Coastal Ocean Dynamics in the Arctic (CODA)

Institutions & participants: seven institutions (plus contractor) and 11 on board participants

1. AWI - Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
2. BOEM - Bureau of Ocean, Energy and Management, USA
3. HSB - Hochschule Bremerhaven, Germany
4. KUL - Catholic University of Leuven, Belgium
5. OSL - Otto-Schmidt-Labor (AWI, AARI), Russia
6. UAF - University of Alaska Fairbanks, USA
7. WMR - Wageningen Marine Research, The Netherlands

The Goal:

The overall goal of the Go-West expedition was to test the hypothesis that entrainment of young Polar cod into the sea-ice habitat in the Chukchi and Beaufort seas during autumn is significant, and hence sea-ice association is an important survival strategy with positive effects on recruitment to the adult population the following summer. The main objectives of the collection of samples were to:

1. Identify sea-ice habitats favorable for Polar cod in terms of physical properties, ice algal biomass and prey composition
2. Test for the presence of deep scattering layers in the underlying water column
3. Quantify the carbon flux between sea ice, plankton, and Polar cod and assess the pre-winter condition of Polar cod
4. Study the connectivity between central Arctic under-ice populations and shelf-based spawning populations

Research and equipments:

During the expedition, samples of Polar cod and its prey were collected in the ice-water interface layer along with high resolution profiles of sea-ice and surface water properties with a Surface and Under-Ice Trawl (SUIT). Backscatter of fish and zooplankton in the water column was recorded with the Sikuliaq´s EK80 echosounder and pelagic communities was sampled with two midwater trawls (Methot trawl and IKMT) and vertical zooplankton nets (CalCET and ring net). A conductivity-temperature—depth probe equipped with a rosette water sampler (CTD) sampled vertical profiles of temperature, salinity and fluorescence and was used to collect water samples for the analysis for chlorophyll ɑ concentration, nutrient concentrations, trophic biomarkers and harmful algae (HAB). During four ice stations, samples of the sea ice for the same parameters (except nutrients) were performed with hyperspectral light measurements needed to derive ice algae biomass from hyperspectral profiles obtained from a sensor mounted on the SUIT. In addition, respiration measurements were performed on abundant zooplankton prey species of Polar cod. Altogether, 11 SUIT stations were completed (1 in open water, 10 under ice), 4 ice stations and 3 midwater trawls. All SUIT deployments were succesful, expanding Sikuliaq’s capability of advanced scientific operations in ice-covered waters. Polar cod were caught at all SUIT stations, totalling 153 fish.

Results:

The research indicate that most fish appeared to be first-year juveniles between 6 and 8 cm in size, pending age determinations. Fish abundance increased with increasing ocean depth, sea-ice draft and abundance of the ice amphipod Onisimus spp.. The mesozooplankton community in the upper 50 m was dominated by the copepod Metridia longa. Respiration experiments indicated that Metridia and, surprisingly, Calanus glacialis from shelf stations were in an active metabolic state. Chlorophyll ɑ concentrations were low (< 0.5 mg m^-3) in the water column. Conversely, visual inspection of ice core filters indicated that ice algal biomass had already begun to accumulate in the autumn sea ice. The trophic relationships between ice algae, zooplankton and sea-ice fauna and Polar cod will be analyzed in detail based on hundreds of biological samples, including diet and trophic biomarker samples. Investigations of otolith microchemistry and population genetics studies on each sampled fish will help elucidate their origins and migration patterns. Preliminary results of this expedition support our hypothesis that juvenile Polar cod associate with sea ice in autumn and show that prey is available to sustain them at the onset of winter.

All samples collected during the expedition were listed in a central sample database and will be searchable through the ARICE dataportal and available for further research by request to the responsible scientist.

Photos, maps & graphs if available

DEARice, PRV Polarstern in the frame of MOSAiC, Central Arctic

DEvelopment of snow/ice/ecosystem models using winter-to-summer ARctic observations of coupled snow, ice, and ecosystem processes (DEARice)

Principal investigator: Martin Schneebeli, WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland

Proposals Partners: Mats A. Granskog, Norwegian Polar Institute, Tromsø, Norway
Polona Itkin, Nansen Environmental and Remote Sensing Center, Bergen, Norway
Roberta Pirazzini, Finnish Meteorological Institute, Helsinki, Finland

Research Icebreaker: PRV Polarstern (AWI, Germany)

Schedule: Attached to the MOSAiC experiment (September 2019-June 2020)

Facebook or blog links: https://follow.mosaic-expedition.org/

Abstract: The once-in-a-lifetime MOSAiC drift experiment will provide observations of the Arctic sea-ice system over a full annual cycle. Sea ice is a unique landscape that is shaped by winds, ocean currents and covered by soft lines of snow drifts. Its pores and cavities can host a unique and complex ecosystem of micro-organisms that provide food for bigger animals such as polar bears and seals. Sea ice interacts with this physical and biological environment and is a continuously evolving element of the changing climate. DEARice will use the most modern instruments to measure how snow, sea ice and the associated ecosystem interact and develop. Our measurements will help representing these relationships in the climate models. Why is the arctic sea ice a continuously evolving “landscape”? Sea ice and snow are both frozen water very close to their melting point. As such they are constantly changing its micro-structure. This gives micro-organisms always new spaces to live in. The sea ice is growing from the ocean under the cold winter atmosphere and is melted back into the ocean by warm air and sun-rays in summer. On a larger scale, the mechanical deformation breaks up the ice and piles up ice ridges, a chaotic build of ice blocks of different sizes, which are conceptually similar to a coral reef. They create cavities at different scales, providing a habitat for micro-organisms. The diverse surface and underwater shapes provide various surfaces that can be dragged by the forces of wind and currents. DEARice will document these situations and developments at the smallest, microscopic scales, somewhat larger meter-scales and up to tens-of-kilometer scales. This will help us connecting the smallest, but important processes to the scales that are used to represent Earth climate in numerical.

PECABEAU, CCGS Amundsen, Beafort Sea

Permafrost Carbon on the Beaufort Shelf (PECABEAU)

Principal investigator: Jorien E. Vonk, Vrije Universiteit Amsterdam, Department of Earth Science, Faculty of Sciences, Earth and Climate Cluster, The Netherlands

Proposals Partners: Dr. Marcel Babin, Takuvik Joint International Laboratory, Canada
Dr. Lisa-Marie Bröder, Vrije Universiteit Amsterdam, Netherlands
Dr. Michael Fritz, Alfred Wegener Institute, Germany
Dr. Matt O'Regan, Stockholm University, Sweden
Dr. Paul Overduin, Alfred Wegener Institute, Germany

Research Icebreaker: CCGS Amundsen (Amundsen Science - ULaval, Canada)

Schedule: Fall 2020

Facebook or blog links: tbc

Abstract: Organic carbon is driving global climate change, which is nowhere more rapid than in the Arctic. On the Arctic Beaufort shelf, rapid changes release, transform and consume organic carbon, changing the shelf ecosystem. The PeCaBEAU project will apply state-of-the-art analytical techniques to track the movement and change of material from land to the ocean. We focus on the sediment column between subsea permafrost and the seafloor, the water column, the atmosphere and the interfaces between these three units. This proposed multi-disciplinary effort integrates previous results from the Canadian Beaufort sea into ongoing pan-Arctic studies. Results will describe the sources, quantities and the quality of organic matter in the water column and in surface sediments. This allows us to improve assessments of the Beaufort shelf as a carbon source or sink, and place these outcomes in the context of the Holocene paleoenvironment and transgressed permafrost.