News and research

New study shows a 50% decline in Krill abundance in the North Atlantic

North Atlantic warming over six decades drives decreases in krill abundance with no associated range shift

A team of UK and French scientists have shown a huge decline in North Atlantic krill over the last 60 years driven primarily by climate variability and North Atlantic warming. Krill, are extremely abundant crustaceans present throughout the world’s oceans. In the North Atlantic, krill are numerically a significant component of the biomass of marine ecosystems particularly in the more boreal and Arctic waters of the North Atlantic. They are an important source of food for commercially exploited fish species, squid and marine mammals such as baleen whales and therefore represent a crucial component in North Atlantic food webs.

50% decline in krill abundance

Examining the data that used long-term observations of krill, the team led by Martin Edwards from Plymouth Marine Laboratory (PML) showed that across the whole North Atlantic basin there has been a 50% decline in krill abundance over the last 60 years. The findings, published in the journal Communications Biology https://www.nature.com/articles/s42003-021-02159-1 show this widespread and abrupt decline has been associated with the warming climate of the North Atlantic observed over the last six decades. This warming has particularly accelerated since the mid 1990s where there was an abrupt shift to warmer conditions in Atlantic waters.

Close up of krill, photo by Brett Wilks

Accelerated pace of changes in the Arctic

In the sub-polar regions of the North Atlantic, where krill are most abundant, concern is growing at the accelerated pace of these changes and the increasing ‘Atlantification’ (i.e warmer more saline Atlantic waters) of these more northern waters and their detrimental effects on Arctic systems. The Arctic sea regions, in particular, are experiencing the strongest warming on the planet (nearly three times as fast as the planetary average) and the loss of sea ice in recent decades has been very rapid. Many regional seas that were once considered as being inhabited exclusively by Arctic flora and fauna have become more influenced by more southerly species as these species move northward as the Arctic warms.

Martin Edwards said ‘as ocean temperature rise, we generally expect species distributions to track towards historically cooler regions in line with their preferred habitats. In this case we would expect the krill populations to simply shift northward to avoid the warming environment and find new habitats in cooler regions of the North Atlantic. However, this study shows for the first time in the North Atlantic that marine populations do not simply just shift their distributions northward due to shifting isotherms to re-establish new geographic habitats’.

Angus Atkinson also from PML said ‘while krill has declined in abundance by 50%, its core latitudinal distribution at ~55 oN has remained markedly stable over the 60 year period’. The study showed that the isotherms for the warmer temperatures are shifting steadily northwards, the cooler isotherms remain in place with an 8 degree difference in average latitudes of the 7-8°C and 12-13°C isotherms in 1958-1967 but only 4 degrees of latitude between the same temperatures in 2008-2017. This ‘habitat squeeze’ and a potential habitat loss of 4 degrees of latitude could be the main driver in the decline of krill populations seen in this study.  This highlights that, as the temperature warms, not all species will be able to tract isotherms as they shift northward and there will be particular species that will win or lose when establishing new habitats as more northerly regions like the Barents Sea and Arctic Ocean become increasingly warmer and ‘Atlantified’.

Humpback whale feeding on krill. Photo by Jean Tresfon

One of the main reasons for the lack of northerly movement is because the centre of krill populations is found in the North West Atlantic (south and east of Greenland) and populations can become spatially constrained due to ocean currents and strong thermal boundaries such as the polar front limiting their northward expansions.  Here, unlike the North East Atlantic which has unimpeded northward flow into the Norwegian and Barents Seas, this region is latitudinally stalled by the sub-polar gyre circulation which is geographically and temporally more robust and forms a thermal barrier to the rapid northward expansion of species.

Martin Edwards further added: ‘while temperature alone does not necessary explain all patterns observed in this study, as trophic interactions would also play an important role, we are currently exploring the mechanisms for these wide-scale changes. We also do not currently know the full ecological ramifications of this dramatic decline in krill but they would presumably have had major consequences for the rest of the marine food-web and will have important implications for ongoing fisheries in the North Atlantic’.

Get the Open Assess paper here: https://www.nature.com/articles/s42003-021-02159-1.pdf

Edwards, M., Goberville, E., Helaouet, P., Lindley, A., Atkinson, A., Burrows, M., Tarling, G. (2021). North Atlantic warming over six decades drives decreases in krill abundance with no associated range shift. Commun Biol 4, 644. https://doi.org/10.1038/s42003-021-02159-1

When variations in Earth’s orbit drive Phytoplankton evolution

Coccolithophores are microscopic algae that form tiny limestone plates, called coccoliths, around their single cells. The shape and size of coccoliths varies according to the species. After their death, coccolithophores sink to the bottom of the ocean and their coccoliths accumulate in sediments, which faithfully record the detailed evolution of these organisms over geological time.

A team of scientists led by CNRS researchers show, in an article published in Nature on December 1, 2021, that certain variations in Earth’s orbit have influenced the evolution of coccolithophores. To achieve this, no less that 9 million coccoliths, spanning an interval of 2.8 million years and several locations in the tropical ocean, were measured and classified using automated microscope techniques and artificial intelligence.

Coccolithophores, an important constituent of the plankton, evolved following the rhythm of Earth’s orbital eccentricity. Credit: Luc Beaufort / CNRS / CEREGE

The researchers observed that coccoliths underwent cycles of higher and lower diversity in size and shape, with rhythms of 100 and 400 thousand years. They also propose a cause: the more or less circular shape of Earth’s orbit around the Sun, which varies at the same rhythms. Thus, when Earth’s orbit is more circular, as is the case today (this is known as low eccentricity), the equatorial regions show little seasonal variation and species that are not very specialized dominate all the oceans. Conversely, as eccentricity increases and more pronounced seasons appear near the equator, coccolithophores diversify into many specialized species, but collectively produce less limestone.

The diversity of coccolithophores and their collective limestome production evolved under the influence of Earth’s orbital eccentricity, which determines the intensity of seasonal variations near the equator. On the other hand, no link to global ice volume or temperature was found. It was therefore not global climate change that dictated micro-algae evolution but perhaps the opposite during certain periods. Credit: Luc BEAUFORT / CNRS / CEREGE

Crucially, due to their abundance and global distribution, these organisms are responsible for half of the limestone (calcium carbonate, partly composed of carbon) produced in the oceans and therefore play a major role in the carbon cycle and in determining ocean chemistry. It is therefore likely that the cyclic abundance patterns of these limestone producers played a key role in ancient climates, and may explain hitherto mysterious climate variations in past warm periods.

In other words, in the absence of ice, the biological evolution of micro-algae could have set the tempo of climates. This hypothesis remains to be confirmed.

More information: Luc Beaufort et al., Cyclic evolution of phytoplankton forced by changes in tropical seasonality, Nature (2021). DOI: 10.1038/s41586-021-04195-7www.nature.com/articles/s41586-021-04195-7

Humans Guilty of Breaking an Fundamental Oceanic Law of Nature

A new international study carried out by the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) has examined the distribution of biomass across all life in the oceans, from bacteria to whales. Their quantification of human impact reveals a fundamental alteration to one of life’s largest scale patterns.

As policymakers assemble in Glasgow for the UN Climate Change Conference, there is growing recognition that human impacts on the environment are going global and growing urgent. However, gaining a quantitative perspective on these impacts has remained elusive.

Scientists from the ICTA-UAB in Spain, the Max Planck Institute for Mathematics in the Sciences in Germany, Queensland University of Technology in Australia, Weizmann Institute of Science in Israel, and McGill University in Canada have used advances in ocean observation and large meta-analyses to show that human impacts have already had major consequences for the larger oceanic species, and have dramatically changed one of life’s largest scale patterns – a pattern encompassing the entire ocean’s biodiversity, from bacteria to whales.

Early samples of marine plankton biomass from 50 years ago led researchers to hypothesize that roughly equal amounts of biomass occur at all sizes. For example, although bacteria are 23 orders of magnitude smaller than a blue whale, they are also 23 orders of magnitude more abundant. This size-spectrum hypothesis has since remained unchallenged, even though it was never verified globally from bacteria to whales. The authors of the study, published in the journal Science Advances, sought to test this hypothesis on a global scale for the first time. They used historical reconstructions and marine ecosystem models to estimate biomass before industrial scale fishing got underway (pre-1850) and compared this data to the present-day.

Figure about the research. Credit: Ian Hatton, Eric Galbraith et al.

“One of the biggest challenges to comparing organisms spanning bacteria to whales is the enormous differences in scale,” recalls ICTA researcher and lead author Dr. Ian Hatton, currently based at the Max Planck Institute for Mathematics in the Sciences. “The ratio of their masses is equivalent to that between a human being and the entire Earth. We estimated organisms at the small end of the scale from more than 200,000 water samples collected globally, but larger marine life required completely different methods.”

Their approach focused on 12 major groups of aquatic life over roughly 33,000 grid points of the ocean. Evaluating the pre-industrial ocean conditions (pre-1850) largely confirmed the original hypothesis: there is a remarkably constant biomass across size classes.

“We were amazed to see that each order of magnitude size class contains approximately 1 gigaton of biomass globally,” remarks co-author Dr. Eric Galbraith of the ICTA-UAB and a current professor at McGill University. However, he was quick to point out exceptions at either extreme. While bacteria are over-represented in the cold, dark regions of the ocean, the largest whales are relatively rare, thus highlighting exceptions from the original hypothesis.

In contrast with an even biomass spectrum in the pre-1850 ocean, an investigation of the spectrum at present revealed human impacts on ocean biomass through a new lens. While fishing and whaling only account for less than 3 percent of human food consumption, their effect on the biomass spectrum is devastating: large fish and marine mammals such as dolphins have experienced a biomass loss of 2 Gt (60% reduction), with the largest whales suffering an unsettling almost 90% decimation. The authors estimate that these losses already outpace potential biomass losses even under extreme climate change scenarios.

“Humans have impacted the ocean in a more dramatic fashion than merely capturing fish. It seems that we have broken the size spectrum – one of the largest power law distributions known in nature,

reflects ICTA researcher and co-author Dr. Ryan Heneghan. These results provide a new quantitative perspective on the extent to which anthropogenic activities have altered life at the global scale. 

More information: The global ocean size spectrum from bacteria to whales (2021). Hatton, Heneghan, Bar-On and Galbraith, 2021, Science Advances.
DOI: 10.1126/sciadv.abh3732

The Ocean Decade at COP 26

COP26 is the 2021 United Nations climate change conference

For nearly three decades the UN has been bringing together almost every country on earth for global climate summits – called COPs – which stands for ‘Conference of the Parties’. In that time climate change has gone from being a fringe issue to a global priority. Specifically part of the COP conference is focused on our oceans and seas. Part of the COP discussions includes the ‘Ocean Decade’.

What is the Ocean Decade?


The Ocean Decade provides a ‘once-in a-lifetime’ opportunity to create a new foundation across the
science-policy interface to strengthen the management of the ocean and coasts for the benefit of humanity and to mitigate the impacts of climate change. The Ocean Decade Implementation Plan outlines ten Decade Challenges, representing the most immediate and pressing needs of the Decade.

Link to the plan below:

Marine Plankton helps produce clouds, but existing clouds keep new ones at bay

Marine plankton breathe more than 20 million tons of sulfur into the air every year, mostly in the form of dimethyl sulfide (DMS). In the air, this chemical can transform into sulfuric acid, which helps produce clouds by giving a site for water droplets to form. Over the scale of the world’s oceans, this process affects the entire climate.

But new research from the University of Wisconsin–Madison, the National Oceanic and Atmospheric Administration and others reveals that more than one-third of the DMS emitted from the sea can never help new clouds form because it is lost to the clouds themselves. The new findings significantly alter the prevailing understanding of how marine life influences clouds and may change the way scientists predict how cloud formation responds to changes in the oceans.

NOAA

 By reflecting sunlight back into space and controlling rainfall, clouds play significant roles in the global climate. Accurately predicting them is essential to understanding the effects of climate change.

More information: Novak et al PNAS October 19, 2021 118 (42) e2110472118; https://doi.org/10.1073/pnas.2110472118

Australian wildfires triggered massive Phytoplankton blooms in the Southern Ocean

Clouds of smoke and ash from wildfires that ravaged Australia in 2019 and 2020 triggered widespread phytoplankton blooms in the Southern Ocean thousands of miles downwind to the east, a new Duke University-led study by an international team of scientists finds.

The study study, published in Nature, is the first to conclusively link a large-scale response in marine life to fertilization by pyrogenic—or fire-made—iron aerosols from a wildfire.

It shows that tiny aerosol particles of iron in the windborne smoke and ash fertilized the water as they fell into it, providing nutrients to fuel blooms at a scale unprecedented in that region.

Phytoplankton require iron for photosynthesis

The study’s co-author Prof Peter Strutton, of the University of Tasmania’s Institute for Marine and Antarctic Studies, likened the phytoplankton bloom to “the entire Sahara desert turning into a moderately productive grassland for a couple of months”. “The entire Southern Ocean is basically low in iron because it’s a long way from dust sources, so any small amount of iron that gets deposited there can cause a strong response,” Strutton said.

The discovery raises intriguing new questions about the role wildfires may play in spurring the growth of microscopic marine phytoplankton, which absorb large quantities of climate-warming carbon dioxide from Earth’s atmosphere through photosynthesis and are the foundation of the oceanic food web.

A satellite image shows smoke from the 2020-21 Australian wildfires covering parts of the Southern Ocean. Credit: Japan’s National Institute of Information and Communication Technology.

Our results provide strong evidence that pyrogenic iron from wildfires can fertilize the oceans, potentially leading to a significant increase in carbon uptake by phytoplankton,” said Professor Nicolas Cassar, of Duke’s Nicholas School of the Environment.

The phytoplankton blooms triggered by the Australian wildfires were so intense and extensive that the subsequent increase in photosynthesis may have temporarily offset a substantial fraction of the fires’ CO2 emissions, he said. But it’s still unclear how much of the carbon absorbed by that event, or by blooms triggered by other wildfires, remains safely stored away in the ocean and how much is released back into the atmosphere. Determining that is the next challenge, Cassar said.

Carbon uptake

The researchers estimate the amount of carbon taken up by phytoplankton cells as a result of the bloom was equivalent to around 95% of the emissions generated by the 2019-20 bushfires.

For that carbon to be permanently removed from the atmosphere, however, the phytoplankton cells would have to sink into the deep ocean and be stored there, Strutton said.

There’s a lot of recycling of energy and biomass that happens in the surface waters. It’s likely that a lot of that carbon that was initially taken up might have been re-released to the atmosphere when those phytoplankton cells started to break down or were eaten.

Large wildfires, like the record-breaking blazes that devastated parts of Australia between 2019 and 2020 and the fires now raging in the western U.S., Siberia, the Amazon, the Mediterranean and elsewhere, are projected to occur more and more frequently with climate change, noted Weiyi Tang, a postdoctoral fellow in geosciences at Princeton University, who co-led the study as a doctoral candidate in Cassar’s lab at Duke.

These fires represent an unexpected and previously under-documented impact of climate change on the marine environment, with potential feedbacks on our global climate.

Pyrogenic aerosols are produced when trees, brush and other forms of biomass are burned. Aerosol particles are light enough to be carried in a fire’s windborne smoke and ash for months, often over long distances.

More information: Widespread phytoplankton blooms triggered by 2019–2020 Australian wildfires, Nature (2021). DOI: 10.1038/s41586-021-03805-8 , www.nature.com/articles/s41586-021-03805-8

Ocean microbes team up and cooperate to gather food when it’s scarce

What do phytoplankton do when the pickings are slim? They must continue to capture nutrients – nitrogen, phosphorus, or iron – to survive, even when these nutrients have become depleted in the sun light layers of the ocean.

One ingenious solution to this challenge is reported in Proceedings of the National Academy of Sciences. In low-nutrient environments, marine microbes can clump together and hook up with even tinier cells that have vibrating, hairlike appendages (cilia) on their surface. The beating cilia create microcurrents that can pull up to 10 times more nutrients within the microbes’ reach – thereby serving up a meal through cooperative work.

Coscinodiscus wailesii diatom (left image) and with attached Pseudovorticella coscinodisci ciliate epibionts (right image). Streak lines were derived from flows generated by the ciliate epibionts. Kanso et al, PNAS, 2021

Even if the ocean is wildly turbulent, microbes can piggyback into consortia for division of labor, says senior corresponding author John H. Costello of Providence College and the Marine Biological Laboratory (MBL), Woods Hole, where much of the research was conducted.

For all conditions but the most radically extreme mixing, these microbial cells live in fluid spaces that are smaller than the eddies caused by ocean mixing,” Costello says. “In their world, the surrounding fluid is always viscous and they do not experience turbulent eddies as humans feel them.”

The team used a technology called Particle Image Velocimetry (PIV) to measure the direction and magnitude of fluid flows around a photosynthetic marine diatom, Coscinodiscus wailesii, with and without an attached ciliate “partner,” Pseudovorticella coscinodisci. They found that fluid flows generated by ciliary beating can increase nutrient flux to the diatom’s cell surface 4-10 times greater than fluxes to the diatom alone.

This cooperative solution is one way microbes can cope in low-nutrient environments. Another previously known tactic for individual cells is sinking to greater depths, which creates relative motion between the cell and surrounding water and increases its exposure to higher nutrient concentrations.

“Sinking might work well in low-nutrient conditions where mixing will recirculate the cells back up from the depths to the sunlit layers,” Costello says. “That way, the risk to the diatom of sinking might be countered by the probability of being returned to high-light environments. But in low-mixing conditions, forming consortia with ciliates could be a more favorable solution to low nutrient availability.”

Diatoms are among the most important groups of single-celled photosynthesisers for removing carbon dioxide from the atmosphere. Thus, the study helps to illuminate ocean-atmospheric exchanges that have become increasingly important for understanding climate change.

More information and link to paper: Eva A. Kanso, Rubens M. Lopes, J. Rudi Strickler, John O. Dabiri, John H. CostelloProceedings of the National Academy of Sciences Jul 2021, 118 (29) e2018193118; DOI: 10.1073/pnas.2018193118

Predicting the future of cod stocks in the North Atlantic

New fisheries management planning tool developed with fewer stocks expected

The future of cod stocks in the North Sea and the Barents Sea may be much easier to predict than before. This is the result of an international research project led by the Helmholtz-Zentrum Hereon and its Institute of Coastal Systems – Analysis and Modeling. For the first time, the team has succeeded in predicting the development of stocks for ten years in advance, taking into account both changes due to climate and fishing. Traditionally, fisheries experts provide catch recommendations for about a year in advance, on the basis of which fishing quotas are negotiated and set internationally. This involves first estimating the size of current cod stocks and then calculating how much cod can be caught in the coming year without endangering the stocks as well as harvesting the stock optimally. The climatic change, long-term changes in water temperature, circulation and mixing, which have a decisive influence on how well cod reproduce, are not included in this prediction, so that the development of stocks can only be predicted in the short term.

Cod stocks will probably decrease in the future: Photo: David Young via Fotolia

Warm North Sea causes stress

As the experts around climate modeler Vimal Koul und Corinna Schrum of Hereon now write in the journal Nature Communications Earth and Environment, they have taken temperature into account in their calculations. For the North Sea, the climate forecast continues to predict temperatures at a high level, so that cod stocks are unlikely to recover or reach earlier levels. As a result, catches are expected to remain low. Things look better for the Barents Sea, where stocks can be managed sustainably.

For the researchers, the challenge was that climate models cannot calculate how much fish there will be in the oceans in the future. They only provide information about expected temperatures. “So we first had to develop a program that translates water temperature into fish quantities,” says Vimal Koul. Among other things, this took into account the ocean temperature in the North Atlantic. The researchers were then able to run their prediction model. The model starts with today’s conditions – the current temperature conditions and the current carbon dioxide content of the atmosphere, and can then calculate how the situation will change as carbon dioxide concentrations increase. The future temperatures are then translated into expected fish abundance and stock sizes.

To test how reliably the model works, it was first compared with real fish data from the 1960s to the present. As it turned out, it was able to correctly estimate fish stocks for the ten-year periods since the early 1960s. In this respect, the researchers led by Vimal Koul can assume that the current view of the coming ten years is also correct.

Fishing intensity taken into account

Another interesting aspect of the study is that the team of climate modelers, fisheries biologists and oceanographers took four different fishing scenarios into account. This allowed them to determine how cod stocks would fare if they were fished at different levels – from intensive to sustainable. In this respect, the results of the current study are very practical. “The 10-year estimates will help the fishing industry better plan catches in the future – so that cod stocks are fished sustainably and gently despite changes in climate,” says Vimal Koul. The new 10-year calculation model could also help fishing companies in their strategic planning – by providing a secure basis for investments in new vessels or processing facilities.

More information: Koul, V., Sguotti, C., Årthun, M. et al. Skilful prediction of cod stocks in the North and Barents Sea a decade in advance. Commun Earth Environ 2, 140 (2021). https://doi.org/10.1038/s43247-021-00207-6

IPBES/IPCC Report: Tackling the biodiversity and climate crises together

Unprecedented changes in climate and biodiversity, driven by human activities, have combined and increasingly threaten nature, human lives, livelihoods and well-being around the world. Biodiversity loss and climate change are both driven by human economic activities and mutually reinforce each other. Neither will be successfully resolved unless both are tackled together.

This is the message of a new IPES/IPCC report, published by 50 of the world’s leading biodiversity and climate experts. This is the first time that the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and the Intergovernmental Panel on Climate Change (IPCC) – two intergovernmental bodies have collaborated together.

The report finds that previous policies have largely tackled biodiversity loss and climate change independently of each other, and that addressing the synergies between mitigating biodiversity loss and climate change, while considering their social impacts, offers the opportunity to maximize benefits and meet global development goals.

Among the most important available actions identified in the report are:

  • Stopping the loss and degradation of carbon- and species-rich ecosystems on land and in the ocean, especially forests, wetlands, peatlands, grasslands and savannahs; coastal ecosystems such as mangroves, salt marshes, kelp forests and seagrass meadows; as well as deep water and polar blue carbon habitats. The report highlights that reducing deforestation and forest degradation can contribute to lowering human-caused greenhouse gas emissions, by a wide range from 0.4-5.8 gigatonnes of carbon dioxide equivalent every year.
A multifunctional ’scape across land, freshwater and marine biomes, including
large, intact wilderness spaces (blue circles), shared spaces (yellow circles) and
anthromes (red circles).

Arctic Climate Change Update 2021: Arctic warming three times faster than the planet

Arctic Monitoring and Assessment Programme (AMAP)

The Arctic has warmed three times more quickly than the planet as a whole, and faster than previously thought according to the newly published ‘Arctic Climate Change update 2021’.

Arctic sea ice looks set to be an early victims of rising temperatures, with each fraction of a degree making a big difference: the chance of it disappearing entirely in summer is 10 times greater if Earth warms by 2 degrees Celsius above pre-industrial levels compared to 1.5C, the goal set by the 2015 Paris Accord.

The finding comes from the Arctic Monitoring and Assessment Programme (AMAP) in their new report.

In less than half a century, from 1971 to 2019, the Arctic’s average annual temperature rose by 3.1C, compared to 1C for the planet as a whole.

That’s more than previously suspected. In a 2019 report on Earth’s frozen spaces, the UN’s Intergovernmental Panel on Climate Change (IPCC) concluded that Arctic surface air temperature has likely increased “by more than double the global average”.

According to researchers, a turning point came in 2004 when the temperature in the Arctic surged for largely unexplained reason.

Since then, warming has continued at a rate 30 percent higher than in previous decades.

Warming has immediate consequences for the Arctic ecosystem, including changes in habitat, food habits and interactions between animals and the migration of some species.

The warming and freshening of the Arctic Ocean directly and indirectly affect the lifecycles of marine species, leading to changes in seasonality, range shifts, and broad changes in ocean ecosystems.

The decline in sea ice affects marine ecosystems through changes in the open water areas and increases in the length of the open water period (both of which affect phytoplankton and ice algae, including the timing of phytoplankton blooms), as well as under-ice productivity and diversity. These changes are having cascading effects through ecosystems, with widespread impacts on the distribution, seasonality, and abundance of a variety of species.

Migrating narwhals

Satellite data show an increasing trend in primary production in all regions of the Arctic Ocean over the past two decades, explained by complex changes in light and nutrient conditions. The consequences of warming near the ocean surface on primary producers in the surface and subsurface ocean layers are still poorly understood, and there is new evidence that dominant Arctic phytoplankton species may be able to adapt to higher temperatures.

Phytoplankton bloom in northern Norway. NASA

Changes in the Arctic Ocean gateways

Warmer waters from the Pacific and Atlantic are also pushing farther into the Arctic Ocean, with widespread impacts on ocean ecosystems. The composition of Arctic plankton communities that form the basis of marine food webs is changing, as are the distribution and abundance of a variety of invertebrate, fish, and marine mammal species.

Find the summary report here:

https://www.amap.no/documents/doc/arctic-climate-change-update-2021-key-trends-and-impacts.-summary-for-policy-makers/3508