AS7: Arctic Ocean Acidification: Pan-Arctic processes and regional ecosystem impacts

Date: Wednesday October 10, 2018

Location: Kero, Lappia Hall

Time: 8:30-10:00

The Arctic Ocean and its surrounding seas are particularly susceptible to ocean acidification (OA) due to greater absorption of CO₂ by cold high-latitude waters and delivery of CO₂-rich water masses into the Arctic basin. Rapidly progressing acidification poses a significant threat to northern communities and commercial fisheries that depend on marine resources in the region. Arctic Monitoring and Assessment Programme finalizes the second Arctic Ocean Acidification (AOA) Assessment in 2018 which provides a five-year update on both physical and biological impacts of OA as well as regionally focused case studies. The results from the AOA 2018 assessment will be published for the first time at the Arctic Biodiversity Congress. A scientific team of authors report here on the status and trends of Arctic OA as well as region specific processes that have emerged since the last AOA in 2013. The format of the session will be five 15 minutes presentations of the assessment results followed by discussions. A total of five case studies discuss region-specific impacts to marine resources and describe economic impacts to rapidly progressing OA. A new component of the 2018 AOA update includes a pan-Arctic economic assessment of acidification impacts to marine resources and northern economies.

Chairs: Emily Osborne, National Oceanic and Atmospheric Administration; Richard Bellerby, Norwegian Institute for Water Research; Claudia Gelfond, University of Alaska, Fairbanks

Format: Series of presentations followed by discussion

Presentations:

1. Arctic ocean acidification: Scientific updates on chemical processes: Richard Bellerby, East China Normal University and Norwegian Institute for Water Research 
2. Biological responses to Arctic ocean acidification: Peter Thor, Swedish Meteorological and Hydrological Institute 
3. Climate change impacts on subsistence fisheries in the Western Canadian Arctic- A framework linking climate model projections to local communities: Nadja Steiner, Fisheries and Oceans Canada 
4. Socioeconomic effects of ocean acidification in northern Norway: A kelp-urchin case study: Philip Wallhead, Norwegian Institute for Water Research 
5. Socio-economic Impacts of Arctic ocean acidification: Henry Huntington, Huntington Consulting 

Abstracts:

Arctic ocean acidification: Scientific updates on chemical processes

Richard Bellerby, East China Normal University and Norwegian Institute for Water Research; Leif Anderson, University of Gothenburg; Emily Osborne, National Oceanic and Atmospheric Administration; Nadja Steiner, Fisheries and Oceans Canada; Melissa Chierici University of Gothenburg; Agneta Fransson, Norwegian Polar Institute; Kumiko Azetsu-Scott, Fisheries and Oceans Canada; Jessica Cross, National Oceanic and Atmospheric Administration; Jón Ólafsson, University of Iceland

We report on overarching concepts of recent advances in our understanding of ocean acidification from a chemical perspective building upon the last AMAP report on ocean acidification (AMAP, 2013). Inflows via the Atlantic and Pacific gateways continue to significantly control dynamics in regional marginal seas such as the Barrents and Chukchi Seas. Specifically in the east, high marine primary production is stimulated by the inflow of high nutrient water from the Pacific Ocean. In other areas, organic matter, both dissolved and particulate, is added to marginal seas via land by river runoff and coastal erosion, a feature that is especially relevant in the Laptev, East Siberian and Chukchi Seas. In the East Siberian and Chukchi Seas the high CO2 concentrations are most obvious in the bottom waters as the majority of the organic matter degradations near the ocean-sediment interface. These CO2- and nutrient-rich bottom water flows off the shelf into the deep Canada Basin where it is “trapped” for some time in the Beaufort Gyre centred around a depth of about 100 m. The horizontal extent of the Beaufort Gyre varies with time depending on the dominating atmospheric pressure field, which leads to that the magnitude of the outflow of the high in CO2 water fluctuates. Surface water of the Beaufort Gyre also contains low salinity water, originating from both sea ice melt and river runoff, both of which have increased with climate warming. Freshening of surface seawater that is in equilibrium with atmospheric CO2 result in a lower pH, if the total alkalinity decreases with salinity, thus also contributing to ocean acidification. Further, freshening also lowers the concentration of calcium ions and therefore further lowers the saturation state of calcium carbonate minerals. Due to the sea-ice cover with ice formation and melt in the Arctic Ocean in parts of the year, sea-ice processes such as CO2-rich brine rejection and calcium carbonate (CaCO3; ikaite) precipitation/dissolution affect the carbonate chemistry in underlying water. Results indicate that ikaite export from sea ice and its dissolution in the underlying seawater can potentially hamper the effect of oceanic acidification and decreased aragonite saturation state ΩA in fall and in winter in ice-covered areas, at the time when ΩA is smallest. This process has been suggested in several studies such as in Young Sound Greenland, in the Canadian Arctic Archipelago, the Nansen Basin, and further confirmed by an investigation in an outdoor-pool experiment in Young Sound.

Biological responses to Arctic ocean acidification

Peter Thor, Swedish Meteorological and Hydrological Institute; Jelmert Anders, Institute of Marine Research; Felix C. Mark, Alfred Wegener Institute; Kai G Shulz; GEOMAR, Helmholtz Centre for Ocean Research; Bjoern Rost, Alfred Wegener Institute; Peter Thor, Norwegian Polar Institute

This presentation will provide an overview of the current state of understanding regarding potential responses to ocean acidification for Arctic species and ecosystems. While we emphasize studies within the Arctic region that have been published recently (i.e. in the last 5 years, since the first AMAP report), for some ecosystem components there remains limited literature and so we have supplemented this with key earlier studies and recent work from other regions. We focus on key taxonomic groups, with potential implications for ecosystem-wide and longer-term adaptive responses highlighted. We also identify how ocean acidification may be modified by human activities driving changes to other abiotic and biotic characteristics.

Climate change impacts on subsistence fisheries in the Western Canadian Arctic- A framework linking climate model projections to local communities

Nadja Steiner, Fisheries and Oceans Canada; William Cheung, University of British Columbia; Helen Drost,  University of British Columbia; Carie Hoover, Fisheries and Oceans Canada; Vicky Lam, University of British Columbia; Lisa Miller, Fisheries and Oceans Canada; Andrés Cisneros-Montemayor, University of British Columbia; Tessa Sou, Fisheries and Oceans Canada; Rashid Sumaila, University of British Columbia; Paul Suprenand, MOTE Marine Laboratory and Aquarium; Travis Tai, University of British Columbia; David L. VanderZwaag, Dalhousie University, Canada

A Western Arctic Bioregion Ocean Acidification case study reviews recent changes and projections of OA in the region and addresses potential impacts and other climate related stressors on the marine ecosystem. The case further evaluates the impacts of these changes on local marine species relevant for subsistence fisheries. The study is an interactive and iterative process using a combination of modelling and analysis tools as follows: 1. Analyze past observed trends. 2. Perform projection simulations with a regional Arctic climate model for 2006-2085, allowing trend estimates on 20-50 year timescales. 3. Feed trends and climate model projections into species distribution/habitat suitability and higher trophic level Ecosim/Ecopath models. 4. Assess physiological responses and thresholds in marine species via literature research and focused lab experiments and include results into the models above. 5. Assess socio-economic impacts via economic models, evaluation of current fishery-economic activities, and discussions with the communities/community representatives. 6. Review the law a governance context implications. This report represents the first iteration of this process, recognizing that refinements and uncertainty analyses are required for the individual components as well as the overall procedure. With respect to step 3, 4 and 5, the report includes a general summary of species as information is available, then highlights the key forage species Boreogadus Saida(Arctic cod).

Socioeconomic effects of ocean acidification in northern Norway: A kelp-urchin case study

Philip Wallhead, Norwegian Institute for Water Research; Wenting Chen, Norwegian Institute for Water Research; Laura Falkenberg, Norwegian Institute for Water Research; Magnus Norling, Norwegian Institute for Water Research; Richard Bellerby, Norwegian Institute for Water Research; Sam Dupont, University of Gothenburg; Camilla with Fagerlig, Norwegian Institute for Water Research; Kasper Hancke, Norwegian Institute for Water Research; Hartvig Christie, Norwegian Institute for Water Research

We developed a kelp-urchin dynamical model to investigate optimal urchin harvesting strategies for the emerging coastal fishery in northern Norway, and to assess the impacts of ocean acidification and climate change. Under projected changes for the next 30 years (1°C warming, 100 μatm pCO2 increase) urchin harvest biomass suffered a roughly tenfold decrease, while the optimal minimum test diameter of harvested individuals remained unchanged at around 40 mm in both present-day and future simulations. This study highlights the pressing need for investigations of organismal sensitivities at moderate levels of warming and acidification, and of other ecosystem effects including disease and higher predation. The model is potentially a useful tool for ecosystem management and harvest optimization in the context of ocean acidification and climate change.

Socio-economic Impacts of Arctic ocean acidification

Henry Huntington, Huntington Consulting

Commercial fisheries in Arctic and subarctic water account for a tenth of the world’s catch (ABA 2013). Subsistence fisheries provide extensive nutritional and cultural benefits to Arctic residents and are based on the deep knowledge and extensive experience of Indigenous peoples and others who live in the Arctic (ABA 2013). The biological impact portion of the AOA report concludes, “forecasted ocean acidification is likely to be sufficient to drive changes in Arctic organisms and ecosystems to a magnitude that will impact the associated human societies.”. This presentation provides an overview of each of the five regional case studies and expounds upon socio-economic impacts such as disruption harvests, effects on employment and income, cultural continuity and health, community demographics, and individual well-being. Results of these cases indicate that the multi-stressor combination of warming of Arctic waters and increasing acidity is expected to have far-reaching effects on Arctic fishes, shellfishes, and the communities and industries that harvest them. Effects are likely to be modest in the near future however there is considerable regional variability and high-levels of uncertainty based on limited scientific understanding. Despite short-term trends, impacts of climate change are projected to increase substantially in the decades to come. It is important to note that not all the effects are major and not all are negative, but it is unlikely that ecosystems and fish stocks will remain stable over the long term under multi-stressor conditions. Significant gaps in our current understanding of ocean acidification on regional scales and within complex Arctic ecosystems and food webs currently hinders bioeconomic modeling of impacts and highlights the need for future targeted research on this topic. We suggest that management actions today can take into account the potential for disruption from ocean acidification and climate change to best prepare for the future. In addition, forward looking economic planning and investment, including training of workers, can aim for greater diversity and adaptability to deal with uncertainty and imminent Arctic Ocean change.