JAMSTEC > Research Institute for Global Change (RIGC) > Institute of Arctic Climate and Environment Research (IACE)  > Arctic Marine Ecosystem Research Group

Institute of Arctic Climate and Environment Research (IACE)

Arctic Marine Ecosystem Research Group

How Advancing Acidification of the Arctic Ocean Affects Organisms

How are changes in the Arctic Ocean affecting marine life? We are seeing greater activity by organisms in a marine region that was formerly covered by ice for almost the entire year. Because a larger marine region is now ice-free in the summer, sunlight penetrates into the ocean over a larger area, and phytoplankton are able to actively photosynthesize there. Furthermore, when the ice that isolates the ocean from the atmosphere disappears, the ocean is directly affected by the wind; ocean mixing, circulation, and other processes are more active; and the nutrients that were somewhat deep in the ocean are being transported to the surface layer, where they enrich the production of organisms. Arctic Ocean changes are benefitting marine life in a variety of ways. But how long will these favorable effects last?

Although on the one hand there are marine areas where organisms are more active, ocean acidification is happening all over the world, but in the Arctic, melting of the ice is diluting the concentration of carbonate ions in seawater, making the Arctic Ocean the fastest-acidifying ocean. Advancing acidification might affect the growth of plankton and juvenile shellfish. It is likely that if their growth is inhibited, the impacts will spread to zooplankton, which feed on phytoplankton, and to fish, which feed on zooplankton. There may also be impacts on people in the fishing and marine products industry, and on our diets, as fish will no longer be caught in some marine areas but will reappear in others. Despite ocean acidification, the oceans have originally been weakly basic, so acid won’t dissolve shellfish shells. Plankton and shellfish make their own skeletons and shells with calcium carbonate. But higher atmospheric CO₂ leads to more CO₂ dissolved in seawater, and that CO₂ reacts with water to produce hydrogen ions. The oceans have a buffering system that controls the increased hydrogen ions by combining them with carbonate ions, becoming bicarbonate ions. Calcium carbonate in organisms dissolves to compensate for the decrease in carbonate ions caused by the reaction with hydrogen ions. In other words, it’s a matter of grave importance to organisms whether seawater is rich in carbonate ions (saturated) or not (under saturated), because in under saturated state there are not enough carbonate ions, which are necessary for the growth of organisms. Understanding the acidification happening in the Arctic Ocean and its impacts on organisms and ecosystems can help predict changes in other world oceans.

To answer the question “How do global warming and acidification affect zooplankton and phytoplankton?” the Arctic Marine Ecosystem Research Group conducts field studies and collects samples in the Arctic Ocean. Additionally, research taking advantage of expertise in measuring the carbonate density of these marine carbonate organisms, in which JAMSTEC leads the world, has confirmed that the zooplankton living in oceans with advanced acidification have low shell density. We are also working on building an “Arctic Sea Ice-Ocean-Ecosystem Model” using a supercomputer to predict the future impacts of global warming and acidification on ecosystems. We hope that by incorporating these two kinds of results into models, we can obtain predictions with lower uncertainty.