Tag: plankton

Phytoplankton and climate change in the North Atlantic

Featured by oceanecology, posted in Research article

A team of UK and French scientists have shown dramatic changes in the abundance of phytoplankton in the North Atlantic over the last 60 years driven primarily by climate variability and North Atlantic warming. In particular, the scientists focused on the important group of phytoplankton collectively known as diatoms. This major phytoplankton group contributes approximately one-fifth of all of Earth’s photosynthesis and up to 30-40% of the global marine primary production each year. As such diatoms are extremely important contributors to marine primary production and to the ocean carbon cycle. In the North Atlantic and its adjacent seas, primary production is primarily driven by these diatoms which produce vast spring blooms that cover the whole ocean every year and fuel the highly productive marine food-webs found there. They also transfer a significant part of the produced energy as carbon to the deep ocean contributing to a significant drawdown of carbon from the atmosphere.

Microscopic image of diatoms. Copyright Charles Kreb

In the study the authors showed that anthropogenic warming and climate variability (including natural climate oscillations and wind) over a multidecadal scale have had important consequences for the productivity and spatial/temporal dynamics of these phytoplankton.  The authors used multidecadal diatom abundance data (>60 years) for large areas of the North Atlantic and the North Sea to show significant spatial and temporal correlations over these scales between diatoms and climate variability. They also examined 50 phytoplankton species individually to investigate seasonal and life-cycle (phenology) patterns at the species level. In summary, the study found that climate warming is having a huge impact on the total abundance of diatoms and species in the North Atlantic over the period of this study. 

Martin Edwards from Plymouth Marine Laboratory who led the study said ‘some of the most important findings in this study include showing an increasing diatom population in northerly systems, but deceasing populations in more southerly systems. We also discovered major phase shifts in diatom abundance synchronous with multidecadal trends in Atlantic climate variability that occurred after the mid-1990s’.  

Phytoplankton bloom in the Northeast Atlantic observed from space. Copyright Nasa

Over the whole area of study there has been an increase in phytoplankton biomass during spring and autumn (where diatoms dominate) with increasing temperatures in cooler regions but a decrease in phytoplankton biomass in warmer regions.  The authors suggest that this is possibly due to increased phytoplankton metabolic rates caused by warming temperatures in colder regions but conversely a decrease in nutrient supply in warmer regions (where warming can enhance stratification and limit nutrient replenishment and hence diatom growth in the surface layers).  Gregory Beaugrand from CRNS in France and a co-author of the study also said ‘that the that autumnal diatom abundance is positively correlated with Sea Surface Temperatures and the increase in Northern Hemisphere Temperatures seen over the last few decades’. The study also found that regional climate warming in some areas of the North Sea has been linked to an increase in certain diatoms that are associated with Harmful Algal Blooms (HABs). Diatom growth in such well mixed areas may be enhanced by temperature as these regions are not inhibited by stratification and hence nutrient availability. These dramatic changes in such a fundamental primary producer for marine food-webs in the North Atlantic will have large on-going ramifications for other marine life from fish to whales found in these oceans.

More information: Edwards, M., Beaugrand, G., Kléparski, L. et al. Climate variability and multi-decadal diatom abundance in the Northeast Atlantic. Commun Earth Environ 3, 162 (2022). https://doi.org/10.1038/s43247-022-00492-9

Humans Guilty of Breaking an Fundamental Oceanic Law of Nature

by oceanecology, posted in News, Research article

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

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

by oceanecology, posted in News, Research article

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

by oceanecology, posted in News, Research article

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

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

Featured by oceanecology, posted in Uncategorized

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

Potentially toxic plankton algae may play a crucial role in the future Arctic

by oceanecology, posted in News, Research article

As the sea ice shrinks in the Arctic, the plankton community that produces food for the entire marine food chain is changing. New research shows that a potentially toxic species of plankton algae that lives both by doing photosynthesis and absorbing food may become an important player in the Arctic Ocean as the future sea ice becomes thinner and thinner.

Microscopic plankton algae, invisible to the naked eye, are the foundation of the marine food web, feeding all the ocean´s living creatures from small crustaceans to large whales. Plankton algae need light and nutrients to produce food by photosynthesis.

A thick layer of sea ice – sometimes covered with snow – can reduce how much sunlight penetrates into the water and stop the algae getting enough light. However, as the sea ice is becoming thinner and less widespread in the Arctic, more and more light is penetrating into the sea. Does this mean more plankton algae and thus more food for more fish, whales and seabirds in the Arctic? The story is not so simple.

More light in the sea will only lead to a higher production of plankton algae if they also have enough nutrients – and this is often not the case. With the recent increase in freshwater melt from Arctic glaciers and the general freshening of the Arctic Ocean, more and more fresh and nutrient-depleted water is running out into the fjords and further out into the sea. The fresher water lies on top of the more salty ocean and stops nutrients from the deeper layers from mixing up towards the surface where there is light. And it is only here that plankton algae can be active.

Mixotrophic algae play on several strings

However, a new study published in the journal Nature – Scientific Reports shows that so-called mixotrophic plankton algae may play a crucial role in the production of food in the Arctic Sea.

When the spring sets in in the Arctic, the metre-thick sea ice begins to melt. Melt ponds on the surface of the sea ice bring so much sunlight into the underlying seawater that the mixotrophic plankton algae start to grow dramatically. During an approx. 9-day period, the plankton can produce up to half of the total annual pelagic production in the high-Arctic fjord, Young Sound, in northeast Greenland. Several mixotrophic algae species are toxic. Photo credit: Lars Chresten Lund Hansen and Dorte H. Søgaard

Mixotrophic algae are small, single-celled plankton algae that can perform photosynthesis but also obtain energy by eating other algae and bacteria. This allows them to stay alive and grow even when their photosynthesis does not have enough light and nutrients in the water.

In northeast Greenland, a team of researchers measured the production of plankton algae under the sea ice in the high-Arctic fjord Young Sound, located near Daneborg.

“We showed that the plankton algae under the sea ice actually produced up to half of the total annual plankton production in the fjord,” says Dorte H. Søgaard from the Greenland Climate Research Centre, Greenland Institute of Natural Resources and the Arctic Research Centre, Aarhus University, who headed the study.

“Mixotrophic plankton algae have the advantage that they can sustain themselves by eating other algae and bacteria as a supplement to photosynthesis when there isn’t enough light. This means that they are ready to perform photosynthesis even when very little light penetrates into the sea. In addition, many mixotrophic algae can live in relatively fresh water and at very low concentrations of nutrients – conditions that often prevail in the water layers under the sea ice in the spring when the ice melts,” Dorte H. Søgaard explains.

Toxic algae kill fish

For nine days, the researchers measured an algal bloom driven by mixotrophic algae occurring under the thick but melting sea ice in Young Sound during the Arctic spring in July, as the sun gained more power and more melt ponds spread across the sea ice, gradually letting through more light.

The algae belong to a group called haptophytes. Many of these algae are toxic, and in this study they bloomed in quantities similar to those previously observed in the Skagerrak near southern Norway. Here, the toxic plankton algae killed large amounts of salmon in Norwegian fish farms.

“We know that haptophytes often appear in areas with low salinity – as seen in the Baltic Sea, for example. It is therefore very probable that these mixotrophic-driven algae blooms will appear more frequently in a more freshwater-influenced future Arctic Ocean and that this shift in dominant algae to a mixotrophic algae species might have a large ecological and socio-economic impact.” says Dorte H. Søgaard.

The researchers behind the project point out that it is the first time that a bloom of mixotrophic algae has been recorded under the sea ice in the Arctic.

More information: An under-ice bloom of mixotrophic haptophytes in low nutrient and freshwater-influenced Arctic waters.http://www.nature.com/articles/s41598-021-82413-y

New research paper on overwintering zooplankton in the North Sea

by oceanecology, posted in Research article

New open access paper published in Progress in Oceanography Overwintering distribution, inflow patterns and sustainability of Calanus finmarchicus in the North Sea.

The modelled abundance (1000 individual/m2) of overwintering C. finmarchicus in the North Sea

Some of the highlights include:

•High overwintering biomass in Norwegian Trench and north-west North Sea shelf.

•Inflow accounts for 41% of North Sea biomass and drives interannual variability.

•Norwegian Trench and East Shetland Atlantic Inflow are important inflow pathways.

•C. finmarchicus in the North Sea is not self-sustained but dependent on the inflow.

•Biomass carried by East Shetland Atlantic Inflow decreases over 2000–2016.

Abstract: Calanoid copepods are key taxa in the North Sea as they are the main food source for many fish stocks, such as herring, mackerel and cod. In this study we use an individual-based model for Calanus finmarchicus embedded in the NORWegian ECOlogical Model system (NORWECOM) to investigate important population parameters such as biomass and abundance, distribution and interannual variability of the overwintering population, as well as the inflow of C. finmarchicus into the North Sea from adjacent areas for the 2000–2016 period. The modelled spatial–temporal patterns of C. finmarchicus abundance is comparable with the Continuous Plankton Recorder (CPR) Survey data in the northern North Sea. The simulated annual mean biomass of C. finmarchicus amounts to 0.94 million-tonnes of carbon. High overwintering biomass appears in the Norwegian Trench as well as in the north-west shelf region of the North Sea. A decreasing trend in the overwintering biomass has been detected on the path of the East Shetland Atlantic Inflow (ESAI) over the simulated period. The inflow of C. finmarchicus biomass into the North Sea from the north constitutes on average 41% of the annual mean biomass in the North Sea during the simulated 17 years, and thus determines the interannual variability of the biomass. We conclude that the C. finmarchicus population in the North Sea is not self-sustained and is highly dependent on the inflow of C. finmarchicus from the Faroe-Shetland Channel and south of the Norwegian Sea. C. finmarchicus enter the North Sea via three branches of the North Atlantic current with variable depths depending on seasons and topography. Beside the western flank of the Norwegian Trench (carrying 57% of the inflow biomass), we suggest that the ESAI is also an important agent carrying 37% of the total C. finmarchicus inflow biomass through the shelf area into the north-west of the North Sea. The annual mean outflow biomass is larger than the inflow biomass (0.52 versus 0.39 million-tonnes carbon per year), which indicates that the North Sea serves as a feeding ground and growth region for C. finmarchicus. This study is a first step towards a better understanding and quantification of the exchange of C. finmarchicus between the open seas, coastal waters and the fjords.

Get the open access paper here:

Download

Scientists complete largest global assessment of ocean warming impacts

by oceanecology, posted in News, Research article

A group of international marine scientists has compiled the most comprehensive assessment of how ocean warming is affecting the mix of species in our oceans – and explained how some marine species manage to keep their cool.

Martin Edwards from the University of Plymouth along with other researchers from the UK, Japan, Australia, USA, Germany, Canada, South Africa and New Zealand analysed three million records of thousands of species from 200 ecological communities across the globe.

Reviewing data from 1985 – 2014, the team led by Michael Burrows of the Scottish Association for Marine Science (SAMS) in Oban showed how subtle changes in the movement of species that prefer cold-water or warm-water, in response to rising temperatures, made a big impact on the global picture. The findings, published in the journal Nature Climate Change [https://www.nature.com/articles/s41558-019-0631-5], show how warm-water species increase and cold-water marine species become less successful as the global temperature rises. However, the study also suggests that some cold-water species, and fish in particular, will continue to thrive by seeking refuge in cooler, deeper water.

Prof Burrows  further added:

“For the period from 1985 – 2014 we created the equivalent of an electoral poll in the ocean, showing swings between types of fish and plankton normally associated with either cold or warm habitats. As species increase in number and move into, or decline and leave, a particular ecological community, the make-up of that community will change in a predictable way. While this may not sound like a big change, it has a considerable impact on species that may already be on, or close to, their maximum temperature tolerance. A gradual temperature change like the one we are witnessing is not going to cause extinctions overnight but it is affecting the success of many species, not least zooplankton such as copepods, which are crucial to the ocean food web”.

Prof Edwards said the truly global study looked at data from the North Atlantic, Western Europe, Newfoundland and the Labrador Sea, east coast USA, the Gulf of Mexico, and the North Pacific from California to Alaska. While the global warming trend was widely seen, the North Atlantic showed the largest rise in average temperature during the time period. This area of the North Atlantic is routinely monitored by one of the world’s largest and longest marine biological surveys known as the Continuous Plankton Recorder (CPR) Survey which provided some key observational data in the global study. The changes observed have been driven by a seemingly small but ecologically significant rise in temperature of almost one degree Celsius in some parts of the ocean since 1985, a rapid change in just three decades. These changes are having huge implications for the abundance and distribution of plankton in our oceans.



Climate-related changes in fish and plankton communities shown by changes in Community Temperature Index values from 1985 to 2015.

Plymouth scientists highlight effects of climate change on UK’s plankton

by oceanecology, posted in News

Marine scientists in Plymouth have led a major study highlighting the effects of climate change on the plankton populations in UK seas.

Published as part of a wide-ranging report by the Marine Climate Change Impacts Partnership (MCCIP), it shows there have been extensive changes in plankton ecosystems around the British Isles over the last 60 years.

It says climate variability and ocean warming have had negative impacts on plankton production, biodiversity and species distributions, which have in turn affected fisheries production and other marine life such as seabirds.

The study was written by world-leading researchers from the University of Plymouth and Plymouth Marine Laboratory, along with colleagues at Marine Scotland Science and the Centre for Environment Fisheries and Aquaculture Science.

It forms part of the MCCIP Report Card 2020, which summarises 26 individual, peer-reviewed scientific reports to provide detailed evidence of observed and projected climate change impacts and identify emerging issues and knowledge gaps.

Emergence of a cold-water ‘blob’ in the North Atlantic sub-polar gyre region

Martin Edwards, Professor of Ocean Ecology at the University of Plymouth, led the report on plankton. He said:

“There have been extensive changes in plankton ecosystems around the British Isles over the last 60 years, mainly driven by climate variability and ocean warming. For example, during the last 50 years there has been a northerly movement of some warmer water plankton by 10° latitude in the North-east Atlantic and a similar retreat of colder water plankton. Future warming is likely to alter the geographical distribution of plankton abundance and these changes may place additional stress on already depleted fish stocks, as well as having consequences for mammal and seabird populations.”

Among the key factors highlighted in the plankton report are:

  • There has been a shift in the distribution of many plankton and fish species around the planet.
  • The North Sea populations of previously dominant and important zooplankton species (the cold water species Calanus finmarchicus, a major food source for fish, shrimp and whales) have declined in biomass by 70% since the 1960s.
  • Species with warmer-water affinities (e.g. Calanus helgolandicus) are moving northwards to replace the species, but are not as numerically abundant.
  • The decline of the European cod stocks due to overfishing may have been exacerbated by climate warming and climate-induced changes in plankton production.
  • Future warming is likely to alter the geographical distribution of primary and secondary open ocean (pelagic) production, affecting ecosystem services such as oxygen production and the removal of carbon dioxide from the atmosphere.

Get the report here:

New open access research paper on plankton biogeography in the North Atlantic

by oceanecology, posted in Research article

New research paper: Plankton biogeography in the North Atlantic Ocean and its adjacent seas: Species assemblages and environmental signatures

Loïck Kléparski, Grégory Beaugrand and Martin Edwards

Ecology and Evolution 2021; 00:1-15. DOI: 10.1002/ece3.7406

Plankton biodiversity is a key component of marine pelagic ecosystems. They are at the base of the food web, control the productivity of marine ecosystems, and provide many provisioning and regulating ecological services. It is therefore important to understand how plankton are organized in both space and time.

Abstract:

Here, we use data of varying taxonomic resolution, collected by the Continuous Plankton Recorder (CPR) survey, to map phytoplankton and zooplankton biodiversity in the North Atlantic and its adjacent seas. We then decompose biodiversity into 24 species assemblages and investigate their spatial distribution using ecological units and ecoregions recently proposed. Finally, we propose a descriptive method, which we call the environmental chromatogram, to characterize the environmental signature of each plankton assemblage. The method is based on a graphic that identifies where species of an assemblage aggregate along an environmental gradient composed of multiple ecological dimensions. The decomposition of the biodiversity into species assemblages allows us to show (a) that most marine regions of the North Atlantic are composed of coenoclines (i.e., gradients of biocoenoses or communities) and (b) that the overlapping spatial distribution of assemblages is the result of their environmental signatures. It follows that neither the ecoregions nor the ecological units identified in the North Atlantic are characterized by a unique assemblage but instead by a mosaic of assemblages that overlap in many places.

Spatial distribution of total
plankton taxonomic richness in the North Atlantic

Get the open access paper here: https://onlinelibrary.wiley.com/doi/10.1002/ece3.7406