{"id":3595,"date":"2017-09-25T15:32:12","date_gmt":"2017-09-25T13:32:12","guid":{"rendered":"https:\/\/npolar.no\/?page_id=3595"},"modified":"2025-11-11T08:28:34","modified_gmt":"2025-11-11T07:28:34","slug":"ocean-acidification-in-the-arctic","status":"publish","type":"page","link":"https:\/\/npolar.no\/en\/themes\/ocean-acidification-in-the-arctic\/","title":{"rendered":"Ocean acidification in the Arctic"},"content":{"rendered":"<section  class='av_textblock_section av-18yec4d-e83d9761a2f656cb5a8009c6832b9617 '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div class='avia_textblock'  itemprop=\"text\" >\n<\/div><\/section>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-3gacrt-a12b653c1cf85132f48e13d3801dc95d\">\n.flex_column.av-3gacrt-a12b653c1cf85132f48e13d3801dc95d{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-3gacrt-a12b653c1cf85132f48e13d3801dc95d av_two_third first flex_column_div av-zero-column-padding  '     ><section  class='av_textblock_section av-36e35l-2cdc38a5a7d9b28565b6569d0bb71dd2 '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div class='avia_textblock'  itemprop=\"text\" ><h2>Status<\/h2>\n<p>In simple terms, it was thought that the sea ice cover restricts the exchange of gases between the water and the atmosphere, and that this also limits primary production in the area \u2013 which also influences gas exchange. Recent research has shown that this is not quite correct, since there are a number of processes associated with sea ice that increase the gas exchange. Researchers are working to quantify the effects of all the different processes in order to produce better estimates of the development of ocean acidification in the Arctic.<\/p>\n<p>More CO<sub>2<\/sub> can be dissolved in cold than in warmer water, so, in respect of ocean acidification, there is a special focus on the Arctic. In addition, the light conditions (24-hour daylight) mean that phytoplankton are active more continuously around the clock, which also results in less pH variation over each 24-hour period. In these areas, it is more interesting to study the annual fluctuations in the phytoplankton\u2019s effect on pH in the upper water layer. Large spatial variation of pH in the Barents Sea has also been documented, which may be due to the oxidation of organic material transported from the land and rivers.<\/p>\n<p>The Arctic is the part of the Earth where the first studies of the effects of ocean acidification are expected to take place. It is at higher latitudes that the sea is expected to first become undersaturated in calcium carbonate. In fact, seasonal undersaturation of aragonite has already been measured at the surface in northern parts of the Arctic Ocean, and models show expectations of constant undersaturation by the middle of this century.<\/p>\n<p>The volume of the summer ice in the Arctic has been dramatically reduced over a few decades, which has led to accelerated absorption of CO<sub>2<\/sub> in the Arctic Ocean, while the brackish water from melting is poor in calcium ions (Ca2 +). Increasing runoff from rivers, where the river water also has a low calcium content, is also contributing to the undersaturation of aragonite in the surface water. Researchers believe we are now heading at full speed towards a tipping point for aragonite in the Arctic Ocean.<\/p>\n<p>Global warming may potentially destabilise large amounts of methane clathrates (frozen methane) stored in the seabed sediments, especially on the continental slopes. This will cause the release of methane into the water column and the atmosphere, which increases vulnerability to ocean acidification in the Arctic. In the East Siberian Sea, large quantities of methane have already been observed leaking from the seabed.<\/p>\n<\/div><\/section><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-33mbc1-92f04359e1b7a2070f79bc1876fb7c8f\">\n.flex_column.av-33mbc1-92f04359e1b7a2070f79bc1876fb7c8f{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-33mbc1-92f04359e1b7a2070f79bc1876fb7c8f av_one_third flex_column_div av-zero-column-padding  '     ><p><section  class='av_textblock_section av-2z06mh-e2b63f298b64fe69df5d702e6f1cfd41 '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div class='avia_textblock'  itemprop=\"text\" ><section class=\"av_textblock_section\"  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role='complementary' class='avia_textblock NP-factsheet-enfold no '   itemprop=\"text\" ><p class='title'>What is ocean acidification?<\/p><div class='hsep'><\/div><div class='NP-factsheet-content'><\/p>\n<p>The term ocean acidification is used for the ongoing reduction in the pH of sea water, caused by increased concentrations of CO<sub>2<\/sub> in the atmosphere. Ocean acidification is caused by emissions of fossil CO<sub>2<\/sub> into the atmosphere. Large amounts of the gas are dissolved in the seawater as carbonic acid and turn the oceans acidic.<\/p>\n<p>Over the last 200 years, the oceans have taken up around a quarter of man-made CO<sub>2<\/sub>, and, worldwide, the average acidity of surface ocean waters has risen by 26 per cent.<\/p>\n<p><\/div><\/div><div tabindex=\"0\" role=\"button\" class=\"NP-factToggle\" style=\"text-align:center;\"><i class=\"fas fa-angle-down fa-2x\"><\/i><\/div><\/section>\n<\/div><\/section><br \/>\n<section  class='av_textblock_section av-2z06mh-e2b63f298b64fe69df5d702e6f1cfd41 '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div class='avia_textblock'  itemprop=\"text\" ><section class=\"av_textblock_section\"  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role='complementary' class='avia_textblock NP-factsheet-enfold no '   itemprop=\"text\" ><p class='title'>Undersaturation of calcium carbonate<\/p><div class='hsep'><\/div><div class='NP-factsheet-content'><\/p>\n<p>Calcium carbonates are important building blocks for shell-building marine organisms. This substance comes in two forms \u2013 calcite and aragonite \u2013 each with their own saturation horizon.<\/p>\n<p>When seawater is oversaturated with these two forms, it facilitates shell-building by marine organisms. Conversely, if the seawater is undersaturated, the water will dissolve shells of aragonite or calcite and shell-building becomes more difficult or impossible.<\/p>\n<p><\/div><\/div><div tabindex=\"0\" role=\"button\" class=\"NP-factToggle\" style=\"text-align:center;\"><i class=\"fas fa-angle-down fa-2x\"><\/i><\/div><\/section>\n<\/div><\/section><\/p><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-fwow9-1830edceb920513669d28990ba552e5a\">\n.flex_column.av-fwow9-1830edceb920513669d28990ba552e5a{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-fwow9-1830edceb920513669d28990ba552e5a av_one_full first flex_column_div av-zero-column-padding  '     ><p><div  class='togglecontainer av-jiebt4nu-d109704bdc5e80c9b1497d6e24f11f36 av-minimal-toggle toggle_close_all' >\n<section class='av_toggle_section av-av_toggle-20e5ea5434b2b5697d30ae62c400bae1'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-12' data-fake-id='#toggle-id-12' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-12' data-slide-speed=\"200\" data-title=\"Undersaturation of calcium carbonate\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Undersaturation of calcium carbonate\" data-aria_expanded=\"Click to collapse: Undersaturation of calcium carbonate\">Undersaturation of calcium carbonate<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-12' aria-labelledby='toggle-toggle-id-12' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>Calcium carbonates are important building blocks for shell-building marine organisms. This substance comes in two forms \u2013 calcite and aragonite \u2013 each with their own saturation horizon.<\/p>\n<p>When seawater is oversaturated with these two forms, it facilitates shell-building by marine organisms. Conversely, if the seawater is undersaturated, the water will dissolve shells of aragonite or calcite, and shell-building becomes more difficult or impossible.<\/p>\n<p>Calcium carbonate is more readily soluble at lower temperatures and increasing pressure, so the saturation horizon is created at a specific depth that varies by sea area. Below this horizon, the calcium carbonate will dissolve, and above it, it can be formed. Aragonite and calcite have different saturation horizons, whereby aragonite is the most easily soluble and will consequently have a saturation horizon in shallower water than calcite has. When increasingly more CO<sub>2<\/sub> is supplied to the sea by the atmosphere, the saturation horizons of both types of calcium carbonate rise, leading to poorer conditions for shell-building organisms. Coldwater corals that live in deep water are especially affected by this.<\/p>\n<p>Laboratory and field studies show that both planktonic and benthic (bottom-dwelling) species experience reduced calcification rates at lower pH. It costs them more energy to build their shells, and the shells may be less robust, which in both cases may have consequences for survival and reproduction.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-av_toggle-3cf18f10f117c8015eb381baaa4b1211'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-13' data-fake-id='#toggle-id-13' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-13' data-slide-speed=\"200\" data-title=\"The chemistry of ocean acidification\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: The chemistry of ocean acidification\" data-aria_expanded=\"Click to collapse: The chemistry of ocean acidification\">The chemistry of ocean acidification<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-13' aria-labelledby='toggle-toggle-id-13' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>How acidic the sea becomes is determined by the concentration of hydrogen ions and carbonate ions in the water. The greater the amount of hydrogen ions and the smaller the amount of carbonate ions, the more acidic the water and the lower the pH.<\/p>\n<p>CO<sub>2<\/sub> molecules occur in seawater in four different forms: undissolved (CO<sub>2<\/sub> (aq)), as carbonic acid (H<sub>2<\/sub>CO<sub>3<\/sub>), and in two ionic forms \u2013 bicarbonate (HCO3-) and carbonate (CO32-). The composition of these carbon compounds depends on temperature, pressure and the chemical composition of the water \u2013 which in turn is affected by latitude and depth. Consequently, ocean acidification is not uniform around the world.<\/p>\n<h3><span id=\"Karbonatsystemet\">The carbonate system<\/span><\/h3>\n<div id=\"attachment_18946\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-18946\" class=\"size-full wp-image-18946\" src=\"https:\/\/npolar.no\/wp-content\/uploads\/2019\/02\/havforsuring.png\" alt=\"karbonatsystemet\" width=\"1024\" height=\"660\" srcset=\"https:\/\/npolar.no\/wp-content\/uploads\/2019\/02\/havforsuring.png 1024w, https:\/\/npolar.no\/wp-content\/uploads\/2019\/02\/havforsuring-450x290.png 450w, https:\/\/npolar.no\/wp-content\/uploads\/2019\/02\/havforsuring-300x193.png 300w, https:\/\/npolar.no\/wp-content\/uploads\/2019\/02\/havforsuring-768x495.png 768w, https:\/\/npolar.no\/wp-content\/uploads\/2019\/02\/havforsuring-705x454.png 705w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><p id=\"caption-attachment-18946\" class=\"wp-caption-text\">Carbon dioxide is dissolved if the equation is read from left to right and is formed if the equation is read in the other direction. This process allows the sea to take up large proportions of atmospheric CO<sub>2<\/sub> without a dramatic reduction in its pH. But the buffer capacity has its limitations and the expectation is that when this effect gradually diminishes, acidification due to the atmospheric CO<sub>2<\/sub> concentration will be amplified. Illustration: Norwegian Polar Institute (from figure by University of Maryland)<\/p><\/div>\n<p>When CO<sub>2<\/sub> is dissolved in the surface water, a weak carbonic acid is formed. The carbonic acid is then split into bicarbonate ions and hydrogen ions. The release of hydrogen ions reduces the pH of the water. They also combine with the carbonate ions and create more bicarbonate ions.<\/p>\n<p>How acidic the sea becomes is determined by the concentration of hydrogen ions and carbonate ions in the water. The greater the amount of hydrogen ions and the smaller the amount of carbonate ions, the more acidic the water and the lower the pH.<\/p>\n<p>This is what is referred to as the carbonate system, which gives seawater its buffering capacity. This means that the increase in dissolved CO<sub>2<\/sub> is less than the amount of CO<sub>2<\/sub> actually taken up by the sea.<\/p>\n<\/div><\/div><\/div><\/section>\n<\/div><br \/>\n<section  class='av_textblock_section av-6httl-36c924249c746d6dda95901779f573ff '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div class='avia_textblock'  itemprop=\"text\" ><h2>Effects of ocean acidification<\/h2>\n<p>Ocean acidification can potentially impact much of marine life, whether through direct or indirect effects. Ocean acidification may cause problems for animals that rely on calcium to build a shell or skeleton. Plankton species, shrimps, lobsters, snails, clams, starfish, sea urchins and corals are vulnerable. In the worst case, many species may die out or be out-competed by others that are better able to tolerate acidification.<\/p>\n<\/div><\/section><\/p><\/div>\n<div  class='flex_column av-av_one_full-7714eba142aeda1f8b5272a3c372b279 av_one_full first flex_column_div  '     ><div id='av-masonry-1' class='av-masonry av-1javoh-8353b428a89ba81b7ff650ef654ccdc2 noHover av-fixed-size av-no-gap av-hover-overlay- av-masonry-animation-active av-masonry-col-3 av-caption-always av-caption-style- av-masonry-gallery ' data-post_id=\"3595\"><div class=\"av-masonry-container isotope av-js-disabled\"><div class='av-masonry-entry isotope-item av-masonry-item-no-image '><\/div><a href=\"https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1.jpg\" data-srcset=\"https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1.jpg 940w, https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1-450x191.jpg 450w, https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1-300x127.jpg 300w, https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1-768x326.jpg 768w, https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1-705x299.jpg 705w\" data-sizes=\"(max-width: 940px) 100vw, 940px\"  aria-label=\"image Limacina helicina\"  id='av-masonry-1-item-16888' data-av-masonry-item='16888' class='av-masonry-entry isotope-item post-16888 attachment type-attachment status-inherit hentry  av-masonry-item-with-image' title=\"Limacina helicina\" alt=\"starfish\"    itemprop=\"thumbnailUrl\" ><div class='av-inner-masonry-sizer'><\/div><figure class='av-inner-masonry main_color'><div class=\"av-masonry-outerimage-container\"><div class='av-masonry-image-container' style=\"background-image: url(https:\/\/npolar.no\/wp-content\/uploads\/limacina-helicina-kruttate-1-705x299.jpg);\"  title=\"Limacina helicina\" ><\/div><\/div><\/figure><\/a><!--end av-masonry entry--><a href=\"https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216.jpg\" data-srcset=\"https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216.jpg 995w, https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216-450x260.jpg 450w, https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216-300x173.jpg 300w, https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216-768x444.jpg 768w, https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216-705x407.jpg 705w\" data-sizes=\"(max-width: 995px) 100vw, 995px\"  aria-label=\"image Glacialis\"  id='av-masonry-1-item-16889' data-av-masonry-item='16889' class='av-masonry-entry isotope-item post-16889 attachment type-attachment status-inherit hentry  av-masonry-item-with-image' title=\"Glacialis\" alt=\"glacialis\"    itemprop=\"thumbnailUrl\" ><div class='av-inner-masonry-sizer'><\/div><figure class='av-inner-masonry main_color'><div class=\"av-masonry-outerimage-container\"><div class='av-masonry-image-container' style=\"background-image: url(https:\/\/npolar.no\/wp-content\/uploads\/NP056806-e1510219229216-705x407.jpg);\"  title=\"Glacialis\" ><\/div><\/div><\/figure><\/a><!--end av-masonry entry--><a href=\"https:\/\/npolar.no\/wp-content\/uploads\/NP043447.jpg\" data-srcset=\"https:\/\/npolar.no\/wp-content\/uploads\/NP043447.jpg 800w, https:\/\/npolar.no\/wp-content\/uploads\/NP043447-450x338.jpg 450w, https:\/\/npolar.no\/wp-content\/uploads\/NP043447-300x225.jpg 300w, https:\/\/npolar.no\/wp-content\/uploads\/NP043447-768x576.jpg 768w, https:\/\/npolar.no\/wp-content\/uploads\/NP043447-705x529.jpg 705w\" data-sizes=\"(max-width: 800px) 100vw, 800px\"  aria-label=\"image Starfish\"  id='av-masonry-1-item-16887' data-av-masonry-item='16887' class='av-masonry-entry isotope-item post-16887 attachment type-attachment status-inherit hentry  av-masonry-item-with-image' title=\"Starfish\" alt=\"starfish\"    itemprop=\"thumbnailUrl\" ><div class='av-inner-masonry-sizer'><\/div><figure class='av-inner-masonry main_color'><div class=\"av-masonry-outerimage-container\"><div class='av-masonry-image-container' style=\"background-image: url(https:\/\/npolar.no\/wp-content\/uploads\/NP043447-705x529.jpg);\"  title=\"Starfish\" ><\/div><\/div><\/figure><\/a><!--end av-masonry entry--><\/div><\/div><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-aegbl-077473a1aa5806e37915b62edb7cf316\">\n.flex_column.av-aegbl-077473a1aa5806e37915b62edb7cf316{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-aegbl-077473a1aa5806e37915b62edb7cf316 av_one_full first flex_column_div av-zero-column-padding  '     ><div  class='togglecontainer av-1geiqh-aee0a17288c382b080abf8f28ec969c8 av-minimal-toggle toggle_close_all' >\n<section class='av_toggle_section av-av_toggle-1a2afe4935df70ee0ec5bda6bcc21a52'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-14' data-fake-id='#toggle-id-14' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-14' data-slide-speed=\"200\" data-title=\"Phytoplankton\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Phytoplankton\" data-aria_expanded=\"Click to collapse: Phytoplankton\">Phytoplankton<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-14' aria-labelledby='toggle-toggle-id-14' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>The effect of ocean acidification on phytoplankton and primary production has been a focus area for research into the subject. Inorganic carbon is an essential building block for photosynthesis, and it has been expected that the increase in CO<sub>2<\/sub> may boost primary production.<\/p>\n<p>For macroalgae, this effect can be seen, but there is no consistent pattern of development for phytoplankton in the Arctic. This may be due to a highly effective system for taking up carbon present in many species of phytoplankton, and different responses are seen in different species, groups and even within the same species. It is difficult to study the effects of ocean acidification at species level alone, since there are a number of determinants that act together and are difficult to isolate in studies.<\/p>\n<p>Most calcifying species appear to have a reduction in their calcification rate at a lower pH, but recent studies also show that a wide range of marine phytoplankton species are resistant to more acidic seas.<\/p>\n<p>The effect of ocean acidification on phytoplankton and primary production has been a focus area for research into the subject. Inorganic carbon is an essential building block for photosynthesis, and it has been expected that the increase in CO<sub>2<\/sub> may boost primary production.<\/p>\n<p>For macroalgae, this effect can be seen, but there is no consistent pattern of development for phytoplankton in the Arctic. This may be due to a highly effective system for taking up carbon present in many species of phytoplankton, and different responses are seen in different species, groups and even within the same species. It is difficult to study the effects of ocean acidification at species level alone, since there are a number of determinants that act together and are difficult to isolate in studies.<\/p>\n<p>Most calcifying species appear to have a reduction in their calcification rate at a lower pH, but recent studies also show that a wide range of marine phytoplankton species are resistant to more acidic seas.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-av_toggle-28aa52f53235e7b4210c1e3de204664d'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-15' data-fake-id='#toggle-id-15' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-15' data-slide-speed=\"200\" data-title=\"Zooplankton\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Zooplankton\" data-aria_expanded=\"Click to collapse: Zooplankton\">Zooplankton<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-15' aria-labelledby='toggle-toggle-id-15' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>In the Arctic, large copepods are important species in the ecosystem \u2013 in the Atlantic sector of the Arctic, the three Calanus species, in particular: <em>C. finmarchicus<\/em>, <em>C. hyperboreus<\/em>, and <em>C. glacialis<\/em> but also the smaller <em>Pseudocalanus sp<\/em>. These are key species that constitute 80-90% of the total zooplankton biomass. They feed on phytoplankton and are a vital food source for a variety of animals \u2013 various species of fish, whales and seabirds.<\/p>\n<p>A number of studies of copepods have been performed, but few of them have assessed effects over several generations. It is possible that ocean acidification is having no negative effects on the Calanus species. The smaller Pseudocalanus species appear to be sensitive to ocean acidification, but they are somewhat adaptable, such that the negative effects diminish from exposure to more acidic water over several generations. Studies of a species\u2019 capacity to adapt to new physical conditions are important in order not to overestimate the effects of ocean acidification. At extremely high levels of CO<sub>2<\/sub>, negative effects are found on <em>C. finmarchicus<\/em>, but there are no proven negative effects on Arctic copepods at the levels expected in the next two hundred years.<\/p>\n<p>Pteropods (sea butterflies) are a group of molluscs that swim in the water using adapted feet. They provide sustenance for predatory species such as herring, salmon, whales and seabirds. The pteropod <em>Limacina helicina<\/em> has been widely studied due to its ecological function as a food source for many organisms, and because it has a shell of aragonite that is prone to degradation at reduced pH. In a number of places in the world, damage to pteropods due to undersaturation of calcium carbonate in the seawater has already been recorded, while other studies show that they are able to maintain their shells in undersaturated water but they expend a lot of energy on doing this, so there is still a negative effect.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-av_toggle-fc738f03ef1eb164a1fe3048e72fbe79'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-16' data-fake-id='#toggle-id-16' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-16' data-slide-speed=\"200\" data-title=\"Seabirds and marine mammals\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Seabirds and marine mammals\" data-aria_expanded=\"Click to collapse: Seabirds and marine mammals\">Seabirds and marine mammals<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-16' aria-labelledby='toggle-toggle-id-16' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>Ocean acidification is not expected to have direct effects on seabirds and marine mammals. There may however still be indirect effects through changes in the food web and consequently in their prey. In particular, mammals and birds that depend on shell-building species are vulnerable to such effects, and must switch to other prey species if their availability declines.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-av_toggle-a10ab85cb79b8176a45f6be712dd56f7'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-17' data-fake-id='#toggle-id-17' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-17' data-slide-speed=\"200\" data-title=\"Ecosystem\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Ecosystem\" data-aria_expanded=\"Click to collapse: Ecosystem\">Ecosystem<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-17' aria-labelledby='toggle-toggle-id-17' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>The effects on an ecosystem are not possible to extract from the totality of the effects different studies have shown. The <a href=\"http:\/\/www.amap.no\/\">Arctic Monitoring and Assessment Programme<\/a> (AMAP) has shown that Arctic marine ecosystems are vulnerable to ocean acidification, but that the actual effects are unknown. Nor is ocean acidification the only change the ecosystems face \u2013 and the combined effects of a warmer climate, more fresh water from rivers, less sea ice, environmental pollutants and ocean acidification are not possible to foresee.<\/p>\n<p>Arctic food chains are relatively simple and are consequently susceptible to influences. Compared to ecosystems closer to the equator, there are few key species at each trophic level. This means that if a prey species becomes almost extinct or moves to other areas due to ocean acidification, there are few alternatives if no new prey species move into the area. Predators must switch to other source of nutrition or relocate. Controlled studies also show complex responses with much variation in response within the same species. Natural selection of those individuals that better tolerate ocean acidification may then be a consequence, with the risk of the diminution of other characteristics being passed on to the next generation.<\/p>\n<p>There is a great need for more studies on the ecosystem effects of ocean acidification, both simpler, predator-prey studies and more complex, ecosystem response studies.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-av_toggle-1790aef3d8c6940ee77961c174c669ab'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-18' data-fake-id='#toggle-id-18' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-18' data-slide-speed=\"200\" data-title=\"Benthic organisms\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Benthic organisms\" data-aria_expanded=\"Click to collapse: Benthic organisms\">Benthic organisms<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-18' aria-labelledby='toggle-toggle-id-18' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>Corals have shells of aragonite, and form reefs of different sizes that are important habitats for many other species. Limited impact has been shown on the most well-known coldwater coral <em>Lophelia<\/em>, especially if other physical and biological conditions are good. <em>Lophelia<\/em> forms large reefs in deep water off the Norwegian coast, and these reefs are important habitats for many deep-water animals. Older Lophelia skeletons and dead corals are expected to gradually dissolve if the water masses have a low pH. Effects on the early life stages of <em>Lophelia<\/em> and on other species are unknown. Nor is there detailed knowledge of the ecological effects of a potential reduction in the benthic habitats that corals create.<\/p>\n<p>Effects on bivalves, echinoderms, crustaceans and a number of other calcifying benthic species will have far-reaching effects on the Arctic food chains. Such species are expected to respond negatively to ocean acidification. For starfish, primarily negative effects of ocean acidification have been documented, while for some species in some studies, no effect has been shown. The different species are vulnerable at different life stages; for example, some species are especially vulnerable during calcification at the larval stage.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-av_toggle-19894f540fdf1588e773902c9789412c'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-19' data-fake-id='#toggle-id-19' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-19' data-slide-speed=\"200\" data-title=\"Fish\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Fish\" data-aria_expanded=\"Click to collapse: Fish\">Fish<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-19' aria-labelledby='toggle-toggle-id-19' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>The effects on many non-calcifying organisms are unknown. In general, both juveniles and adult fish have the capacity and flexibility in their acid-base balance systems to handle the expected change in pH over this century. Conversely, fish eggs and early larval stages have less-developed systems for handling changes in CO<sub>2<\/sub> levels in the water. There are few studies that provide a basis for saying anything very substantive about the complete effects, since laboratory studies over several developmental stages, not to mention several generations, are nearly non-existent.<\/p>\n<p>Knowledge of the effects on fish derive almost exclusively from non-Arctic species, with the exception of the commercial species of Atlantic cod (<em>Gadus morhua<\/em>) and walleye pollock (<em>Theragra chalcogramma<\/em>), where a number of studies have been performed. For these species, developmental abnormalities have been found at early life stages, while juveniles and adult fish appear to be handling increased CO<sub>2<\/sub> levels well. The studies were conducted on southern populations of these species, so the knowledge may not necessarily be transferable to the populations living in Arctic waters. It is possible that adaptations among Arctic populations to a different climate and other habitats increase sensitivity to ocean acidification, or that their physiological ability to adapt to increased CO<sub>2<\/sub> levels may be limited at low water temperatures that restrict physical processes in the fish.<\/p>\n<p>The polar cod (<em>Boreogadus saida<\/em>) is a circumpolar key species. It accounts on its own for 75% of the energy transported from zooplankton to vertebrate predators such as seabirds, seals, whales and polar bears. Calanoid copepods are the main food of polar cod, and there is not expected to be a negative effect from ocean acidification on the polar cod due to access to prey.<\/p>\n<\/div><\/div><\/div><\/section>\n<\/div><\/div>\n<div  class='avia-video av-7t7u9-9acb35cc913f6c43ad1fa79111298c48 avia-video-16-9 av-no-preview-image avia-video-load-always av-lazyload-immediate av-lazyload-video-embed'  itemprop=\"video\" itemtype=\"https:\/\/schema.org\/VideoObject\"  data-original_url='https:\/\/vimeo.com\/65514648'><script type='text\/html' class='av-video-tmpl'><div class='avia-iframe-wrap'><iframe loading=\"lazy\" title=\"Arctic Ocean Acidification (2013) - Short (3 minute) version\" src=\"https:\/\/player.vimeo.com\/video\/65514648?dnt=1&amp;app_id=122963&autoplay=0&loop=0&controls=1&muted=0\" width=\"1280\" height=\"720\" frameborder=\"0\" allow=\"autoplay; fullscreen\" allowfullscreen><\/iframe><\/div><\/script><div class='av-click-to-play-overlay'><div class=\"avia_playpause_icon\"><\/div><\/div><\/div>\n<div  class='togglecontainer av-ld8rwwg8-400adc555f1ce4cf95d699308ee5c9cd av-minimal-toggle toggle_close_all' >\n<section class='av_toggle_section av-ld8rvpi6-23aa7c3aa6627656e38e0a93f1c2a285'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-20' data-fake-id='#toggle-id-20' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-20' data-slide-speed=\"200\" data-title=\"Related pages\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: Related pages\" data-aria_expanded=\"Click to collapse: Related pages\">Related pages<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-20' aria-labelledby='toggle-toggle-id-20' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p><a href=\"https:\/\/npolar.no\/en\/themes\/climate-change-in-antarctica\/\">Climate change in Antarctica<\/a><\/p>\n<p><a href=\"https:\/\/npolar.no\/en\/themes\/climate-processes-and-drivers\/\">Climate \u2013 processes and drivers<\/a><\/p>\n<p><a href=\"https:\/\/npolar.no\/en\/themes\/global-climate-change\/\">Global climate change<\/a><\/p>\n<p><a href=\"https:\/\/npolar.no\/en\/themes\/climate-indicators\/\">Climate indicators<\/a><\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-ld8rwgvo-8663c1b02170f3a5dc1be669e3417477'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-21' data-fake-id='#toggle-id-21' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-21' data-slide-speed=\"200\" data-title=\"References\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: References\" data-aria_expanded=\"Click to collapse: References\">References<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-21' aria-labelledby='toggle-toggle-id-21' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p>Arctic Monitoring and Assessment Programme (AMAP), 2018.&nbsp;<a href=\"https:\/\/www.amap.no\/documents\/doc\/amap-assessment-2018-arctic-ocean-acidification\/1659\">AMAP Assessment 2018: Arctic ocean acidification<\/a>.<\/p>\n<\/div><\/div><\/div><\/section>\n<section class='av_toggle_section av-ld8rwvci-fa394aab1434a2a8eab6b13aafb084af'  itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\" ><div role=\"tablist\" class=\"single_toggle\" data-tags=\"{All} \"  ><p id='toggle-toggle-id-22' data-fake-id='#toggle-id-22' class='toggler  av-title-above '  itemprop=\"headline\"  role='tab' tabindex='0' aria-controls='toggle-id-22' data-slide-speed=\"200\" data-title=\"External links\" data-title-open=\"\" data-aria_collapsed=\"Click to expand: External links\" data-aria_expanded=\"Click to collapse: External links\">External links<span class=\"toggle_icon\"><span class=\"vert_icon\"><\/span><span class=\"hor_icon\"><\/span><\/span><\/p><div id='toggle-id-22' aria-labelledby='toggle-toggle-id-22' role='region' class='toggle_wrap  av-title-above'  ><div class='toggle_content invers-color '  itemprop=\"text\" ><p><a href=\"https:\/\/forskning.no\/havforskning-norsk-polarinstitutt-partner\/surere-vann-endrer-livet-i-havet\/1249717\">Surere vann endrer livet i havet<\/a>&nbsp;(Forskning.no)<\/p>\n<\/div><\/div><\/div><\/section>\n<\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":2,"featured_media":3144,"parent":3607,"menu_order":19,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"tags":[],"emne":[104],"class_list":["post-3595","page","type-page","status-publish","has-post-thumbnail","hentry","emne-ocean-acidification"],"acf":[],"_links":{"self":[{"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/pages\/3595","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/comments?post=3595"}],"version-history":[{"count":5,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/pages\/3595\/revisions"}],"predecessor-version":[{"id":50182,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/pages\/3595\/revisions\/50182"}],"up":[{"embeddable":true,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/pages\/3607"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/media\/3144"}],"wp:attachment":[{"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/media?parent=3595"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/tags?post=3595"},{"taxonomy":"emne","embeddable":true,"href":"https:\/\/npolar.no\/en\/wp-json\/wp\/v2\/emne?post=3595"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}