Changes in oxygen concentrations in our ocean can disrupt fundamental biological cycles

By: Thomas Schmitt Attorney on November 25, 2019 / comment : 0 Biodiversity, Climate Change, Ecosystems, Natural Heritage, Oceans, Wildlife

New research led by scientists at the University of Bristol has shown that the feedback mechanisms that were thought to keep the marine nitrogen cycle relatively stable over geological time can break down when oxygen levels in the ocean decline significantly.

On Aug. 11, 2015, a NASA satellite captured this false-color image of a large bloom of cyanobacteria (Nodularia) swirling in the Baltic Sea. These cyanobacteria fix inorganic atmospheric nitrogen (N2) into a form available to Life,  a process fundamental for marine ecosystems. In our paper we show that nitrogen fixation becomes even more important when the state of oxygenation of the ocean declines [Credit: NASA Earth Observatory/USGS]

The nitrogen cycle is essential to all forms of life on Earth - nitrogen is a basic building block of DNA.

The marine nitrogen cycle is strongly controlled by biology and small changes in the marine nitrogen cycle have major implications on life. It is thought that the marine nitrogen cycle has stayed relatively stable over geological time due to a range of different feedback mechanisms.

These feedback mechanisms are called 'the nitrostat'. However, exactly how the global marine nitrogen cycle and the associated feedback mechanisms responded to past severe changes in marine oxygenation is not well understood.

The team used a data-constrained earth system model to show show that under these deoxygenated conditions the ocean can become extremely depleted in nitrogen as the total bioavailable nitrogen inventory collapses relative to phosphorous.

At the same time the ocean transitions from an oxic-nitrate ocean to an anoxic ammonium ocean. The substantive reduction in the ocean bioavailable-N inventory in response to change in marine oxygenation may represent a key biogeochemical vulnerability.

Lead author Dr David Naafs from the University of Bristol's School of Earth Sciences, said: "Our results demonstrate that changing the amount of oxygen in the ocean can have disastrous effects on vital biogeochemical cycles such as the nitrogen cycle, which is essential for all forms of Life."

Co-author Dr Fanny Monteiro, from Bristol's School of Geographical Sciences, added: "Our modelling results are in agreement with the sparsely available proxy data from the geological past."

Co-author Professor Ann Pearson from Harvard University, said: "Our modelling results show the impact of changes in ocean oxygenation on the marine nitrogen cycle for places and time periods for which we do not (yet) have sufficient proxy data."

The strength and state of the marine nitrogen cycle and biological pump in the ocean are highly susceptible to disruptions in the level of oceanic oxygen.

As oxygen levels in the oceans are currently declining and expected to decline significantly more in the coming decades due to anthropogenic activities, the results indicate that the marine nitrogen cycle might be significantly disrupted in the future.

Their findings are published in the journal Proceedings of the National Academy of Sciences.

Source: University of Bristol [November 25, 2019]

Climate change is reshaping communities of ocean organisms

By: Thomas Schmitt Attorney on November 25, 2019 / comment : 0 Biodiversity, Climate Change, Ecosystems, Natural Heritage, Oceans, Wildlife

Climate change is reshaping communities of fish and other sea life, according to a pioneering study on how ocean warming is affecting the mix of species.

This is a black and yellow rockfish (Sebastes chrysomelas) in the Channel Islands National Marine Sanctuary off Southern California [Credit: Claire Fackler/CINMS, NOAA]

The study, published in the journal Nature Climate Change, covers species that are important for fisheries and that serve as food for fish, such as copepods and other zooplankton.

"The changes we're observing ripple throughout local and global economies all the way to our dinner plates," said co-author Malin Pinsky, an associate professor in the Department of Ecology, Evolution, and Natural Resources in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick.

"We found dramatic evidence that changing temperatures are already reshaping communities of ocean organisms," Pinsky said. "We found that warm-water species are rapidly increasing and cold-water marine species are decreasing as the global temperature rises. Changes like this are often disrupting our fisheries and ocean food chains."

An international team of scientists also found evidence that species in some places can avoid declines by seeking refuge in cooler, deeper water - like plants on land that move to higher elevations to avoid heat, Pinsky said.

The scientists compiled the most comprehensive assessment of how ocean warming is affecting the mix of species in our oceans. They looked at fishes, invertebrates such as crabs and other crustaceans and plankton in the North Atlantic and North Pacific, across two continents and two oceans. They analyzed three million records of thousands of species from 200 ecological communities across the globe from 1985 to 2014.

Regions with stable temperatures (the Northeast Pacific and Gulf of Mexico, for example) show little change in species dominance, while warming areas (the North Atlantic, for example) are experiencing strong shifts toward the dominance of warm-water species, the study says.

Temperature is a fundamental driver for change in marine systems, with restructuring of communities in the most rapidly warming areas. Still, the data "suggest a strong prognosis of resilience to climate change for these communities," the study says.

"We're now trying to understand how the changes we see in the ocean compare with those on land and in freshwater ecosystems," said Pinsky, who is also a sabbatical professor at the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig.

Source: Rutgers University [November 25, 2019]

Almost a third of tropical Africa's flora faces extinction

By: Thomas Schmitt Attorney on November 21, 2019 / comment : 0 Africa, Biodiversity, Ecosystems, Endangered Species, Natural Heritage

31.7% of tropical Africa’s vascular plant species could be threatened with extinction, reveals an international study coordinated by an IRD researcher, published in the journal Science Advances. Using a new approach based on the key elements of the assessment process used by the International Union for Conservation of Nature (IUCN), for the first time researchers have been able to assess the potential conservation status of tropical flora on the scale of a continent.

Mountains of the eastern arch of Tanzania. The flora of this region is threatened with extinction [Credit: IRD - Thomas Couvreur]

Given the anthropological and climate threats facing nature, the conservation of tropical biodiversity is a major challenge. To encourage the implementation of better biodiversity management practices, countries and international agreements on biodiversity refer to the assessments of species "at risk of extinction" performed by the IUCN as part of a standardised procedure (See Red List of Threatened Species). This approach remains the most comprehensive and objective means of identifying species in need of protection.

However, while the conservation status of the majority of vertebrate species has been assessed, the same cannot be said for plants, although they are critical to earth ecosystems. This is especially true in tropical regions where the flora is very diverse but remains poorly documented.

In this study, the researchers developed a new fast and automatic approach based on key elements of the conservation assessment process used by the IUCN. Their objective was to provide relevant information on the conservation status of a large number of plant species at broad scales, in the form of Preliminary Automated Conservation Assessments (PACA).

The researchers therefore applied this methodology to the RAINBIO database, which contains over 600,000 georeferenced occurrences of plants in tropical Africa across more than 20,000 vascular plant species.

Infographic of the main results [Credit: Thomas L.P. Couvreur]

After classifying these species into six categories - which include species that are "probably or potentially threatened", those that are "potentially rare" and those that are "potentially not threatened" - they reveal that almost a third (31.7%) of the 22,036 vascular plant species studied are potentially threatened with extinction, and an additional 33.2% are potentially rare (they could be threatened in the near future).

After determining the most endangered species, the researchers identified four regions in Africa that are particularly exposed: Ethiopia, central Tanzania, the south of the Democratic Republic of the Congo and the West African tropical rainforests.

They highlight the advantages of this approach, based on the preliminary automated conservation assessments, in terms of cost reduction, time saving and the potential to carry out large-scale assessments. "This study is the first large-scale assessment of the potential conservation status of the tropical African flora, explicitly using the IUCN's methodology", explains botanist Thomas Couvreur from the IRD who coordinated the study.

"These assessments could provide crucial information for improving biodiversity management and promoting sustainable economic development in Africa. They are, however, not intended to replace the comprehensive assessments carried out by the IUCN which lead to official statuses. The two approaches are complementary, and a significant international effort is still needed to assess all plant species in Africa", he urges.

"These results were possible because the partners involved agreed to share their data", says Bonaventure Sonke, Professor at the Laboratory of Systematic Botany and Ecology of the Ecole Normale Superieure (University Yaounde 1, Cameroon). "This is a strong signal to encourage researchers to share their data, in order to obtain results on a larger scale".

Source: Institut de recherche pour le developpement [November 21, 2019]

Melting Mongolian ice patches may threaten reindeer pastoralism, archaeological artefacts

By: Thomas Schmitt Attorney on November 20, 2019 / comment : 0 Climate Change, Ecosystems, Heritage, Indigenous Cultures, Mongolia, Natural Heritage

Northern Mongolian "eternal ice" is melting for the first time in memory, threatening the traditional reindeer-herding lifestyle and exposing fragile cultural artifacts to the elements, according to a study published in the open-access journal PLOS ONE by William Taylor from the Max Planck Institute, Germany, and the University of Colorado-Boulder, USA, and colleagues.

This is a domestic reindeer saddled for riding outside a Tsaatan summer camp in Khuvsgul province,  northern Mongolia [Credit: Julia Clark]

The mountainous tundra of the northern Mongolian steppes features "munkh mus" or "eternal ice", ice patches which remain intact even in the summer. For the reindeer-herding Tsaatan people, they provide a place for heat-stressed reindeer to cool down, as well as fresh water, useful plants, and a reprieve from summer insects for herders and reindeer alike.

The authors of the present study visited the Ulaan Taiga Special Protected Area of Mongolia to investigate the potential for cultural artifacts in the ice. They conducted an archaeological survey on foot and on horseback, and also held ethnographic interviews with eight local families over 2018.

(Left): Image of a persistent snow and ice patch in Mengebulag taken in 2006, showing domestic reindeer using the  patch, and (right): the same patch in 2018, which local residents indicated had melted for the very first time [Credit: Taylor et al, 2019]

The families interviewed described how many ice patches had melted for the first time in memory between 2016 and 2018, while stressing the importance of eternal ice for reindeer and herding families alike. Many herders complained that recent declines in pasture quality had led to reindeer sickness and death.

The archaeological survey revealed a number of wooden artifacts at one melted ice patch site which dated from the 1960s, when herders moved into the area - the first discovered artifacts from this region. Organic materials are preserved in ice but degrade rapidly upon exposure to the elements, meaning that melting ice could affect the archaeological record.

A domesticated reindeer from northern Mongolia [Credit: O. Batchuluun]

As Mongolia continues to warm at a higher rate than the global average, the authors note that the eternal ice appears to be melting due to the increasing summer temperatures--and stress this puts both cultural heritage and traditional reindeer herding at extreme risk in the years to come.

The authors add: "This study shows us that global climate change is an urgent threat in Inner Asia - melting ice is threatening both reindeer herding as a way of life, and the region's cultural heritage."

Source: Public Library of Science [November 20, 2019]

Amazon deforestation and number of fires show summer of 2019 not a ‘normal’ year

By: Thomas Schmitt Attorney on November 18, 2019 / comment : 0 Biodiversity, Brazil, Ecosystems, Natural Heritage, Rainforests

The fires that raged across the Brazilian Amazon this summer were not 'normal' and large increases in deforestation could explain why, scientists show.

Recently deforested land in the Amazon [Credit: Marizilda Cruppe/ Rede Amazonia Sustentavel]

The perceived scale of the Amazon blazes received global attention this summer. However, international concerns raised at the time were countered by the Brazilian Government, which claimed the fire situation in August was 'normal' and 'below the historical average'.

An international team of scientists writing in the journal Global Change Biology say the number of active fires in August was actually three times higher than in 2018 and the highest number since 2010.

Although fires in the Amazon can occur in a number of ways, the scientists show that there is strong evidence to link this year's increases to deforestation.

They have used evidence collected from the Brazilian Government's DETER-b deforestation detection system -- which calculates deforestation by interpreting images taken by NASA satellites.

This shows that deforestation in July this year was almost four times the average from the same period in the previous three years. This is important as deforestation is almost always followed by fire -- the cut vegetation is left to dry before being burned.

Professor Jos Barlow, lead author of the paper said: "The marked upturn in both active fire counts and deforestation in 2019 therefore refutes suggestions by the Brazilian Government that August 2019 was a normal fire month in the Amazon."

Saving 'half Earth' for nature would affect over a billion people

By: Thomas Schmitt Attorney on November 18, 2019 / comment : 0 Biodiversity, Climate Change, Ecosystems, Environment, Natural Heritage, Wildlife

As the extinction crisis escalates, and protest movements grow, some are calling for hugely ambitious conservation targets. Among the most prominent is sparing 50% of the Earth's surface for nature.

Credit: Kate Ter Haar

'Half Earth' and similar proposals have gained traction with conservationists and policy makers. However, little work has gone into identifying the social and economic implications for people.

Now, researchers have produced the first attempt to assess how many and who would be affected if half the planet was 'saved' in a way that secures the diversity of the world's habitats.

A team of scientists analysed global datasets to determine where conservation status could be added to provide 50% protection to every "ecoregion": large areas of distinct habitats such as Central African mangroves and Baltic mixed forests.

Even avoiding where possible "human footprints" such as cities and farmland, their findings suggest a "conservative" estimate for those directly affected by Half Earth would be over one billion people, primarily in middle-income countries.

Many wealthy and densely populated nations in the Global North would also need to see major expansions of land with conservation status to reach 50% - this could even include parts of London, for example.

The study's authors, led by University of Cambridge researchers, say that while radical action is urgently required for the future of life on Earth, issues of environmental justice and human wellbeing should be at the forefront of the conservation movement.

"People are the cause of the extinction crisis, but they are also the solution," said Dr. Judith Schleicher, who led the new study, published today in the journal Nature Sustainability. "Social issues must play a more prominent role if we want to deliver effective conservation that works for both the biosphere and the people who inhabit it."

Towards the end of next year, the leaders of most of the world's nations will aim to agree global targets for the future of conservation at the Convention on Biological Diversity in Beijing.

"Goals that emerge from the Convention on Biological Diversity could define conservation for a generation," said Schleicher, who conducted the research while at the University of Cambridge's Conservation Research Institute and its Department of Geography.

"We need to be ambitious given the environmental crises. But it is vital that social and economic implications at local levels are considered if the drivers of biodiversity loss are to be tackled. The lives of many people and the existence of diverse species hang in the balance."

The idea of a 'Half Earth' for nature was popularised by famed biologist E.O. Wilson in his 2017 book of the same name. More recently, a 'Global Deal for Nature' - aiming for 30% protection by 2030 and 50% by 2050—has been endorsed by a number of leading environmental organisations. However, these proposals have been ambiguous about "exact forms and location", say Schleicher and colleagues.

Based on their analyses, researchers cautiously estimate that an additional 760 million people would find themselves living in areas with new conservation status: a fourfold increase of the 247 million who currently reside inside protected areas.

The team call for proponents of Half Earth, and all supporters of area-based conservation, to "recognise and take seriously" the human consequences—both negative and positive—of their proposals.

"Living in areas rich in natural habitat can boost mental health and wellbeing. In some cases, protected areas can provide new jobs and income through ecotourism and sustainable production," said Schleicher.

"However, at the other extreme, certain forms of 'fortress' conservation can see people displaced from their ancestral home and denied access to resources they rely on for their survival."

While conservation coverage has been increasing, species numbers continue to plummet—suggesting a "disconnect" between international targets and implementation at local and regional levels, argue the team.

"Conservation needs strong action to protect life on earth, but this must be done in a way that takes account of people and their needs," said co-author Dr. Chris Sandbrook from Cambridge's Department of Geography.

"Failing to consider social issues will lead to conservation policy that is harmful to human wellbeing and less likely to be implemented in the first place."

Conservation is not just a problem for people of the Global South. Recent reports on UK wildlife revealed devastating declines in iconic species. Yet the study reveals that achieving 50% ecoregion coverage could even see parts of central London become protected. "It highlights the absurdity of hitting arbitrary targets," Sandbrook said.

Source: University of Cambridge [November 18, 2019]

Global climate change concerns for Africa's Lake Victoria

By: Thomas Schmitt Attorney on November 14, 2019 / comment : 0 Africa, Climate Change, Earth Science, Ecosystems, Natural Heritage

Global climate change could cause Africa's Lake Victoria, the world's largest tropical lake and source of the Nile River, to dry up in the next 500 years, according to new findings from a team of researchers led by the University of Houston. Even more imminent, the White Nile -- one of the two main tributaries of the Nile -- could lose its source waters in just a decade.

View of modern Lake Victoria from the Kenya shoreline where fishing is a vital part of economy and very  susceptible to changes in climate that affect the amount of rainfall and levels of the lake [Credit: Emily Beverly]

Using ancient sediment from outcrops along the edge of the lake, Emily Beverly, assistant professor of sedimentary geology at the UH College of Natural Sciences and Mathematics, along with researchers at Baylor University, generated a water-budget model to see how Lake Victoria's levels respond to changes in evaporation, temperature, rainfall and solar energy. Their findings, published in Earth and Planetary Science Letters, indicate a rapid lake level decline was very possible tens of thousands of years ago and could happen again in the future.

"Our model predicts that at current rates of temperature change and previous rates of lake level fall, Lake Victoria could have no outlet to the White Nile in as little as 10 years. Every major port in Lake Victoria could be landlocked within a century, and Kenya could lose access to the lake in 400 years," Beverly explained.

The result would significantly affect the economic resources supplied by the lake and the livelihoods of approximately 40 million people living in the Lake Victoria Basin.

- Kenya and Tanzania depend on the lake's freshwaters to support their fishing industries because the lake harvests more than one million tons of fish annually.

Members of the team explored outcrops along Lake Victoria in western Kenya. These sediments were used to understand the history of the lake over the past 100,000 years [Credit: Emily Beverly]

- Uganda would be deprived of its primary source of electricity via hydropower and the water that sustains the Nile during non-flood stages.

- The Kagera River basin, which is the main river that flows into Lake Victoria, feeds rainwater to Rwanda and Burundi which rely on agriculture and livestock production.

Lake Victoria gets most of its water from rain, and each year, the area gets about 55 inches of rainfall. The sediment analyzed from along the lake shows rainfall levels from 35,000 to 100,000 years ago were about 28 inches, or almost half of what they are today. The water-budget model in the study shows low amounts of rainfall caused the lake to dry up at least three times in the past 100,000 years and could happen again.

"It's so warm there and the sun is so strong because you are at the equator that evaporation is very high," said Beverly. "If the water balance is thrown off, the lake can dry up very quickly. It doesn't take much of a drop in precipitation to change it."

Author: Sara Tubbs | Source: University of Houston [November 14, 2019]

Last Arctic ice refuge is disappearing

By: Thomas Schmitt Attorney on November 12, 2019 / comment : 0 Arctic, Climate Change, Earth Science, Ecosystems, Environment, Natural Heritage

The oldest and thickest Arctic sea ice is disappearing twice as fast as ice in the rest of the Arctic Ocean, according to new research.

New research finds the Arctic’s oldest and thickest ice is more mobile and is vanishing twice as fast as ice in the rest of the Arctic [Credit: NOAA]

A new study in AGU's journal Geophysical Research Letters finds ice in the Arctic Ocean north of Greenland is more mobile than previously thought, as ocean currents and atmospheric winds are likely transporting the old, thick ice found there to other parts of the Arctic. As a result, ice mass in the area - the last place researchers think will lose its year-round ice cover - is declining twice as fast as ice in the rest of the Arctic, according to the new findings.

Climate models predict Arctic summers will soon be ice-free - perhaps as early as 2030 - meaning less than 1 million square kilometers (386,000 square miles) of summer sea ice will blanket the Arctic Ocean. Arctic warming has already created an environment which leads to younger sea ice. Watch a visualization of the age of Arctic sea ice over time here.

Most ice covering the Arctic is only one to four years old, according to the National Snow and Ice Data Center. As thin, young ice melts in future summers, only a 2,000-kilometer (1,240-mile) arc of ice will remain, stretching from the western Canadian Arctic Archipelago to Greenland's northern coast. In this slice of the Arctic, which experts call the Last Ice Area, sea ice is more than five years old and can measure more than four meters (13 feet) thick.

The new research suggests the Last Ice Area is a dynamic place encompassing two sub-regions where ice thickness fluctuates by 1.2 meters (4 feet) from year to year. Ice is becoming thinner in two distinct subregions, which are losing 0.4 meters (1.3 feet) of ice thickness per decade, amounting to a 1.5-meter (5 foot) loss of ice since the late 1970s, according to the new study.

Annual mean sea ice thickness (m) over the Arctic Ocean from 1979 – 2018. The black line  surrounds the area where the ice thickness exceeds 3 m and can be considered as the  region known as the Last Ice Area. The white lines surround the two areas where the ice thickness exceeds 4m [Credit: Kent Moore/University of Toronto]

"We can't treat the Last Ice Area as a monolithic area of ice which is going to last a long time," said Kent Moore, an atmospheric physicist at the University of Toronto in Canada and lead author of the new study. "There's actually lots of regional variability."

For wildlife who rely on sea ice for survival, the Last Ice Area offers a sanctuary, and is the final place they can retreat to in a warming world. Understanding how the Last Ice Area changes throughout the year could help pinpoint which spots are best suited to provide a refuge for wildlife who are dependent on sea ice, according to the study's authors.

Places with less ice movement, for example, may provide more suitable conditions for a wildlife sanctuary, as the ice will remain longer. The new study presents context for policymakers to consider when they establish protected areas in the Arctic, Moore said.

"Eventually the Last Ice Area will be the region that will repopulate the Arctic with wildlife," Moore said. "If we lose all the ice, we lose those species. This area will be a refuge where species can survive and hopefully expand their regions once the ice starts returning."

A dynamic zone

The Last Ice Area is home to the Arctic's oldest and thickest ice because ocean currents and atmospheric winds carry patches of floating ice in a circular pattern. These blocks of ice crash into each other and pile up along the northern edges of Greenland and Canada. Researchers, however, know little about how ice in this region moves and melts during the year.


This lack of knowledge prompted Moore and his colleagues to track changes in the Last Ice Area. In the new study, the team modeled sea ice cover, thickness and motion across the zone from 1979 to 2018. Their model, based on satellite observations and atmospheric data, revealed two regions with distinct seasonal and inter-annual fluctuations - one to the east and one to the west.

In both regions, sea ice was thinner and covered less area in the summer and early fall than in the Arctic winter, though ice thickness in the west tended to hit its minimum earlier in the season. Ice motion in the eastern portion of the Last Ice Area appeared to be more stable. Western ice - controlled by winds blowing clockwise - has begun moving faster, which could be the result of thinning ice.

According to Moore, the loss of ice in the Last Ice Area is likely due to ice movement out of the region, particularly in the west. If sea ice is thinner and moving faster, pieces at the margins will flow first into the open ocean, followed by larger bits from the center, like a big traffic jam.

"Historically, we thought of this place as an area that just receives ice," said David Barber, an Arctic climatologist from the University of Manitoba in Canada who was not involved in the new study. "But these results are teaching us that this is a dynamic area."

Source: American Geophysical Union [November 12, 2019]