Neonicotinoids: The New DDT?

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Could a million freshwater turtles help clean up some of Australia's polluted rivers? A team of scientists believes, they could!

by Larry Powell

The freshwater turtle, Emydura macquarii. Credit: Claudia Santori.

For well over a century, invasive freshwater fish from Europe - carp (originally from China) - have been released, either deliberately or accidentally from fish farms, into Australian waterways. The fish, now widely regarded as pests, are thriving. 

Their habitat includes rivers flowing through the Murray-Darling Basin of New South Wales. Those vast waterways support, through irrigation and other means, about 40% of agricultural production for the entire country - not to mention vital aquatic eco-systems and drinking water for about three million people. 

Baby Emydura macquarii. Credit: Tom Burd.

By contrast, the clock is ticking for Australia's native freshwater turtles. The new study says the most common species has declined by up to 91 percent in the past 40 years. It blames urbanization, which damages their habitat and makes the turtles more vulnerable to mass die-offs from disease. They're also being run over by vehicles on roadways. And foxes, like the carp, also introduced from elsewhere, are destroying their nests. 

Ironically, the scientists have now discovered that the turtles could play a vital role in any plan to rid the rivers of the nuisance carp. As carp die, they decompose and give off ammonia, which is toxic to other creatures.

An experiment the researchers carried out showed, convincingly, that the turtles could act as an effective "clean-up crew." Turns out, they have a huge appetite for the carcasses of the fish, a trait which would improve water quality, to everyone's benefit.

Day nine of the experiments - with turtles present in the water, 

the carp carcass has been completely devoured. 

Credit: Ricky Spencer and Claudia Santori.

The researchers built "artificial wetlands" made up of several large tanks like the one above. They placed dead carp in all of them. Then they put the turtles, in groups of four, in some. The tanks were monitored, either until the carcasses had fully decomposed or been completely eaten by the turtles.

The results, as documented in a study, now published in the journal, Nature,  are striking.

The turtles stripped carp carcasses to skeletons within five days, whereas, without turtles present, the carcasses took more than 27 days - more than five times longer - to decompose. In the tanks with the turtles, ammonia levels fell and dissolved oxygen levels - which aquatic animals need to survive, recovered. Without turtles, the water progressively deteriorated and became very dirty. While crayfish, prawns, and shrimp act similarly, none are as effective as the turtles. 

The leader of the research team, Ricky Spencer of Western Sydney University, believes, a plan by the Australian Government to use a biological agent to get rid of the carp, could be devastating. That's because, without lots of turtles doing the scavenging, mounds of dead fish rotting in the rivers would only emit more ammonia and compound problems of water pollution.

“We’re not just talking about the health of our rivers here," Prof. Spencer adds.  "We’re talking about human health. These are river systems that supply our drinking water and irrigate the fruit and vegetables we eat. So turtles are critical to sustaining the health of humans, as well as our rivers.”

But, with turtle populations on the decline, finding enough to do an effective job, will be daunting. So, the research team is proposing what it calls "Australia's largest, community-empowered conservation program. Local communities will lead 'expansionary conservation,' where we aim to release more than one million extra turtles throughout southeastern Australia each year." A crowd-funding program has been launched to pay for the effort.

Kiss the Ground (Official Movie Trailer 2020)

The Arctic is burning like never before — and that’s bad news for climate change

Nature

Wildfire smoke at the Arctic Circle.  MIKOFOX ⌘ 2020 Vision

Fires are releasing record levels of carbon dioxide, partly because they are burning ancient peatlands that have been a carbon sink. Story here.

RELATED:

New research finds - global heating is melting vast northern fields of permafrost so fast that - within decades - they'll likely stop cooling the planet as they have for millennia - and start doing just the opposite.

Ecology: Conservation and food system changes needed to bolster biodiversity

Trees, shrubs and debris are burned on the Canadian prairies to make  way

for more cropland. A PinP photo.

Nature

Declines in terrestrial biodiversity from habitat conversion could be reversed by adopting a combination of bold conservation methods and increases in the sustainability of the food system, a modelling study published in Nature suggests.

Human pressures, such as the destruction of natural habitats to make way for agriculture and forestry, are causing rapid declines in biodiversity, and placing at risk the ecosystem services upon which we depend. Ambitious targets for biodiversity have been proposed, but it is unclear how these targets can be achieved whilst retaining the ability to feed a growing population. Using land-use and biodiversity models, David Leclère and colleagues show how this is possible. 

Conservationists need to increase the amount of actively managed land, restore degraded land and adopt generalized landscape-level conservation planning. Meanwhile, we need to eat fewer animal-derived calories, waste less food and find ways to intensify food production sustainably.

If this double-pronged strategy is followed, more than two thirds of future biodiversity losses from habitat conversion could be avoided, the authors suggest. However, they caution that other threats, such as climate change, must also be addressed to truly reverse biodiversity declines.

"Live fast. Die young!" Fast-growing trees could store less carbon

Nature Communications

Faster growth leads to a shorter lifespan in trees, according to a paper published in Nature Communications. The findings could have implications for predictions of how much carbon forests can store under climate change.

A black spruce (Picea mariana) forest.
Photo credit - Western Arctic National Parklands

A relationship between faster tree growth rates and shorter tree lifespan has been shown in some trees, particularly in cold-adapted conifers, but whether this applies across species and climates has been disputed. Such a trade-off would be at odds with the use of tree growth rates as a proxy for carbon storage, and cast doubt on Earth system model predictions of global forest carbon storage.

Roel Brienen and colleagues analysed a large dataset of tree-ring data representing 110 tree species across all continents except Africa and Antarctica. They report that faster growth is linked to reduced tree lifespan both across and within tree species, and show that this is not due to covariance with climate or soil variables. Using model forest simulations based on data about the black spruce (Picea mariana), they further show that this trade-off has the potential to slow down or even reverse the global forest carbon sink in the future.

These findings challenge most predictions of future carbon storage in mature forests, casting doubt on the persistence of the global forest carbon sink in the coming decades. The authors call for efforts to integrate tree-growth lifespan trade-offs in process-based models of forest carbon dynamics.

Arctic ocean moorings shed light on winter sea ice loss

Science Daily

A table iceberg in the Norwegian Arctic. Such icebergs are rare
as they calve from shelf ice, which is also rare. They're normally
a typical form of iceberg in the Antarctic. This one is about 12m high
and about half the size of a soccer field. Photo by Andreas Weith.

The eastern Arctic Ocean's winter ice grew less than half as much as normal during the past decade, due to the growing influence of heat from the ocean's interior, researchers have found. Story here.

Meet the Canadian farmers fighting climate change

The Narwhal
Conservation and agriculture have often been at odds. But as Ottawa develops the first federal carbon offset standard, farming techniques that reduce greenhouse gas emissions are having a moment. Story here.

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Here's another farmer who fits the category described, above.

Zack Koscielny is a fifth generation farmer located near Strathclair,
Manitoba implementing regenerative agriculture practices on his farm.
He has a degree in Agroecology and is a graduate of the Soil Health Academy.

Animal behaviour: Leading the young: older male elephants prove they are "up to the tusk!"

Journal: Scientific Reports

Male elephants socialising along the Boteti River. Credit: Connie Allen.

Older male elephants may have important roles to play as experienced leaders to younger males when navigating unknown or risky environments, according to a study published in Scientific Reports. 

In long-lived species, such as elephants and whales, older individuals often respond more appropriately to complex, changing environments, which may benefit younger group members. However, research in this area has tended to focus on females.

Connie Allen and colleagues investigated grouping behaviour and patterns of leadership in 1,264 male African savannah elephants travelling on elephant pathways to and from the Boteti River in the Makgadikgadi Pans National Park (MPNP), Botswana. 

Male African elephants congregate along hotspots of social activity
on the Boteti River. Credit: Connie Allen.

The authors found that lone elephants accounted for 20.8% (263 elephants) of sightings on elephant pathways. Adolescent males travelled alone significantly less often than expected, unlike mature adult males who were more likely to travel alone than expected, which may suggest that lone travel is riskier for younger, newly independent and less experienced individuals. Older adults were significantly more likely to travel at the front of groups of males, suggesting that mature adult bulls act as repositories for ecological knowledge and that they may be important leaders during collective movement in all-male groups of African savannah elephants.

Old males being considered reproductively redundant is commonly used as an argument to support the legal trophy hunting of old males, according to the authors who suggest that such selective harvesting of older males could disrupt the wider bull society and the inter-generational flow of accumulated ecological knowledge.

Mining for renewable energy could worsen threats to biodiversity

Nature Communications

A University of Queensland photo.

Threats to biodiversity could increase in the future as more mines target materials used for renewable energy production, suggests a study in Nature Communications.

Renewable energy production is necessary to mitigate climate change. However, only 17% of current global energy consumption is achieved through renewable energies. Generating the required technologies and infrastructure will lead to an increase in the production of many metals, which may create potential threats for biodiversity.

Laura Sonter and colleagues mapped mining areas globally and assessed their coincidence with biodiversity conservation sites. The authors found that mining potentially influences approximately 50 million km2 of the Earth’s land surface with 82% of mining areas targeting materials used in renewable energy production. When looking at the spatial overlap between mining areas and conservation sites, they found that 8% of mining areas coincided with nationally-designated Protected Areas, 7% with Key Biodiversity Areas and 16% with Remaining Wilderness (sites considered important priorities for halting diversity loss).

The authors discovered that a greater proportion of pre-operational mines are targeting materials needed for renewable energy production (nearly 84%) compared to around 73% of operational mines. They also observed that pre-operational mines targeting renewable materials also appear to be more densely packed together than those targeting other materials.

Increasing the extent and density of mining areas will cause additional threats to biodiversity suggest the authors, and they argue that without strategic planning these new threats to biodiversity may surpass those averted by climate change mitigation.

New research finds - global heating is melting vast northern fields of permafrost so fast that - within decades - they'll likely stop cooling the planet as they have for millennia - and start doing just the opposite.

by Larry Powell

Permafrost Slide at Big Fox Lake, Ontario, Canada - 2015.
A Creative Commons photo by MIKOFOX. 

For thousands of years, so-called "permafrost peatlands" in Earth's Northern Hemisphere have been cooling the global climate. They’ve done it by trapping large amounts of carbon and nitrogen which would otherwise escape into the air as harmful greenhouse gases. 

More recently however, scientists have observed, they've been melting due to manmade global heating. As they melt, they're releasing large amounts of substances like methane - a potent greenhouse gas - into the air. 

But, without proper maps, it's been hard for scientists to get a handle on the degree to which this might be happening - until now. New ones drawn up using thousands of field observations, show; Permafrost peatlands cover a vast area of almost four million square kilometres.

And, to quote from the study, "Under future global warming scenarios, half to nearly all of peatland permafrost could be lost this century.” 

This means their age-old role, mostly as net “sinks,” keeping harmful greenhouse gases in the ground, would transform to a net source of atmospheric carbon, primarily methane.

A permafrost "slump" in Alaska. A USGS photo.

The research concludes that, “Although northern peatlands are currently a source of global cooling, permafrost thaw attributable to anthropogenic climate warming may convert peatlands into a net source of warming."

The findings were published recently in PNAS, the proceedings of the National Academy of Sciences (US). 

But the impact of the nitrogen trapped in these fields cannot be underestimated, either. A separate study, also published in PNAS about three years ago, reveals, "Some 67 billion tons of it, accumulated thousands of years ago, could now become available for decomposition, leading to the release of nitrous oxide (N2O) to the atmosphere. N2O is a strong greenhouse gas, almost 300 times more powerful than CO2 for warming the climate. Although carbon dynamics in the Arctic are well studied, the fact that Arctic soils store enormous amounts of nitrogen has received little attention so far. We report that the Arctic may become a substantial source of N2O when the permafrost thaws, and that N2O emissions could occur from surfaces covering almost one-fourth of the entire Arctic."

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