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]

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]

Evolutionary diversity is associated with Amazon forest productivity

By: Thomas Schmitt Attorney on November 11, 2019 / comment : 0 Biodiversity, Ecosystems, Evolution, Genetics, Rainforests, South America

An international team of researchers led by the University of Leeds have revealed for the first time that Amazon forests with the greatest evolutionary diversity are the most productive.

The Amazon canopy [Credit: Fernanda Coelho,  University of Leeds]

The team used long term-records from 90 plots as part of the Amazon Forest Inventory Network (RAINFOR) and ForestPlots.net to track the lives and productivity of individual trees across the Amazon region. By combining these records with DNA sequence data - which identified the evolutionary relationships among all the species - the team was able to investigate the links between how fast different forests grow and their diversity.

Their study demonstrated that the plots with the greatest evolutionary diversity were a third more productive compared to areas with the least evolutionary diversity.

The finding suggest that evolutionary diversity should be an important consideration when identifying priority areas for conservation.

Study lead author Fernanda Coelho from the School of Geography at Leeds said: "Understanding how biodiversity affects productivity in tropical forests is important because it allows us to understand how conservation strategies can best be designed to maximise protection of species and the services that these ecosystems provide.

"Our results indicate that we should include evolutionary history in conservation priorities - because ecosystem function may be higher in areas where species come from right across the tree of life'.

The paper is published in Nature Ecology & Evolution.

Source: University of Leeds [November 11, 2019]

Human activities drying out the Amazon: NASA study

By: Thomas Schmitt Attorney on November 06, 2019 / comment : 0 Amazonia, Biodiversity, Brazil, Ecosystems, Environment, Natural Heritage, Rainforests, South America

A new NASA study shows that over the last 20 years, the atmosphere above the Amazon rainforest has been drying out, increasing the demand for water and leaving ecosystems vulnerable to fires and drought. It also shows that this increase in dryness is primarily the result of human activities.

The Amazon rainforest [Credit: Marcio Isensee e Sa/Adobe Stock]

Scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, analyzed decades of ground and satellite data over the Amazon rainforest to track both how much moisture was in the atmosphere and how much moisture was needed to maintain the rainforest system.

"We observed that in the last two decades, there has been a significant increase in dryness in the atmosphere as well as in the atmospheric demand for water above the rainforest," said JPL's Armineh Barkhordarian, lead author of the study. "In comparing this trend to data from models that estimate climate variability over thousands of years, we determined that the change in atmospheric aridity is well beyond what would be expected from natural climate variability."

So if it's not natural, what's causing it?

Barkhordarian said that elevated greenhouse gas levels are responsible for approximately half of the increased aridity. The rest is the result of ongoing human activity, most significantly, the burning of forests to clear land for agriculture and grazing. The combination of these activities is causing the Amazon's climate to warm.

When a forest burns, it releases particles called aerosols into the atmosphere—among them, black carbon, commonly referred to as soot. While bright-colored or translucent aerosols reflect radiation, darker aerosols absorb it. When the black carbon absorbs heat from the sun, it causes the atmosphere to warm; it can also interfere with cloud formation and, consequently, rainfall.

Why It Matters

The Amazon is the largest rainforest on Earth. When healthy, it absorbs billions of tons of carbon dioxide (CO2) a year through photosynthesis—the process plants use to convert CO2, energy and water into food. By removing CO2 from the atmosphere, the Amazon helps to keep temperatures down and regulate climate. But it's a delicate system that's highly sensitive to drying and warming trends.

The image shows the decline of moisture in the air over the Amazon rainforest, particularly across the south  and southeastern Amazon, during the dry season months - August through October - from 1987 to 2016. The measurements are shown in millibars [Credit: NASA/JPL-Caltech, NASA Earth Observatory]

Trees and plants need water for photosynthesis and to cool themselves down when they get too warm. They pull in water from the soil through their roots and release water vapor through pores on their leaves into the atmosphere, where it cools the air and eventually rises to form clouds. The clouds produce rain that replenishes the water in the soil, allowing the cycle to continue. Rainforests generate as much as 80% of their own rain, especially during the dry season.

But when this cycle is disrupted by an increase in dry air, for instance, a new cycle is set into motion—one with significant implications, particularly in the southeastern Amazon, where trees can experience more than four to five months of dry season.

"It's a matter of supply and demand. With the increase in temperature and drying of the air above the trees, the trees need to transpire to cool themselves and to add more water vapor into the atmosphere. But the soil doesn't have extra water for the trees to pull in," said JPL's Sassan Saatchi, co-author of the study. "Our study shows that the demand is increasing, the supply is decreasing and if this continues, the forest may no longer be able to sustain itself."

Scientists observed that the most significant and systematic drying of the atmosphere is in the southeast region, where the bulk of deforestation and agricultural expansion is happening. But they also found episodic drying in the northwest Amazon, an area that typically has no dry season. Normally always wet, the northwest has suffered severe droughts over the past two decades, a further indication of the entire forest's vulnerability to increasing temperatures and dry air.

If this trend continues over the long term and the rainforest reaches the point where it can no longer function properly, many of the trees and the species that live within the rainforest ecosystem may not be able to survive. As the trees die, particularly the larger and older ones, they release CO2 into the atmosphere; and the fewer trees there are, the less CO2 the Amazon region would be able to absorb—meaning we'd essentially lose an important element of climate regulation.

The study was published in Scientific Reports.

Author: Esprit Smith | Source: NASA [November 06, 2019]

Figuring out the total human impacts on biodiversity

By: Thomas Schmitt Attorney on November 05, 2019 / comment : 0 Biodiversity, Ecosystems, Environment, Natural Heritage, Wildlife

How much have humans affected the population of other species on the planet? A new methodology for documenting the cumulative human impacts on biodiversity aims to answer this question.

Gulf grouper [Credit: Alfredo Barroso, Flickr/Sea Around Us]

Dubbed EPOCH -for Evaluation of Population Change- the methodology was developed by a group of scientists from universities in Europe, Asia, and North America. It provides a standardized framework for organizing disperse data on individual species or populations of animals and plants that have been affected by urbanization, pollution, fishing, hunting, over-harvesting, and other anthropogenic activities.

Assessing impact requires contrasting the status of current populations with a reference state or baseline. However, the experts were faced with the challenge that for many species the baseline is not known because they have been impacted for a long time and those impacts have been forgotten. This phenomenon responds to the concept of 'Shifting Baseline Syndrome' developed by the Sea Around Us' principal investigator and University of British Columbia professor Daniel Pauly.

"So we decided to define baseline not as a particular date but as a reference state, that is, the population size expected today in the absence of human actions," said Ana Rodrigues, lead author of the study from the University of Montpellier. "This means that any changes in relation to this baseline reveal the cumulative extent of human impacts."

Rodrigues explained that the flexible definition allows for the baseline to be tailored to each population being studied and to be estimated from historical data, by comparing with an area where a species is still relatively intact, or by relating a less-known to a better-known species.

"For example, for Gulf grouper, we set the baseline in the 1940s, before industrial exploitation kicked off. Back then, it was considered a fish commonly present in the Gulf of California, according to historical records and interviews with old fishers. However, as time passed, data shows that it has been depleted through past overfishing and that in more recent years it is considered rare by new generations," Rodrigues said. "This is an example of a relatively recent temporal baseline but for the bowhead whales in the Barents Sea we went back 400 years, prior to industrial whaling."

Credit: Valentina Ruiz Leotaud

Each assessed species is classified into one of 11 EPOCH categories, based on the extent to which humans have affected their population numbers. Species can have experienced little change, their numbers may have moderately or severely increased or decreased, they may have been extirpated, or they may be newly present in a certain area.

"The advantage of going back in time and establishing these categories is that we can see the whole picture of how much more we have lost over hundreds of years," said Deng Palomares, a co-author of the study and the Sea Around Us project manager at UBC's Institute for the Oceans and Fisheries.

According to Palomares, her own experience setting an as-early-as-possible baseline, as it is done with the Sea Around Us' fisheries data, has already been useful to establish the reality of how much has been lost.

"Now, imagine going back hundreds of years, when explorers describe codfish as being so abundant in the coastal waters off Newfoundland that one could walk on their backs. With this framework, we bring the baseline nearer to a population's 'virgin biomass,' that is, the biomass that was there before humans invented powerful machines to harvest these resources and in the process destroy them."

For Rodrigues, Palomares, and their colleagues, these assessments that show the cumulative level of population change through time should help set realistic targets for the recovery of affected populations. "With the United Nations having just declared 2021-2030 the Decade of Ecosystem Restoration, ensuring future conservation efforts take into account the history of past change is more pertinent than ever," they wrote in their paper.

The paper was published in Philosophical Transactions B.

Author: Valentina Ruiz Leotaud | Source: Sea Around Us [November 05, 2019]