'Fatal attraction': Small carnivores drawn to kill sites, then ambushed by larger kin

MARCH 18, 2020

by University of Washington

In many parts of the world, there is an imbalance in the food chain.

Without top predators such as wolves and grizzly bears, smaller meat-eating animals like coyotes and foxes or grazers such as deer and elk can balloon in population, unchecked. This can initiate more deer-vehicle collisions, scavenging by urban coyotes and other unnatural human-animal interactions.

University of Washington researchers have discovered that large predators play a key yet unexpected role in keeping smaller predators and deer in check. Their "fatal attraction" theory finds that smaller predators are drawn to the kill sites of large predators by the promise of leftover scraps, but the scavengers may be killed themselves if their larger kin return for seconds.

The study, published March 18 in the journal Ecology Letters, is the first to examine carnivore killing and scavenging activities in relation to each other across dozens of landscapes around the world. Patterns that emerged from their analysis could be used to make important management decisions about large carnivores worldwide, the authors said.

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Species at the extremes of the food chain evolve faster, study says

December 17, 2018, University of Tennessee at Knoxville

Reef fish species at the extremes of the food chain—those that are strict herbivores or strict fish predators—evolve faster than fish species in the middle of the food chain with a more varied diet, according to a new study published in Nature Ecology and Evolution.

The paper, co-authored by Samuel Borstein, a Ph.D. candidate in the Department of Ecology and Evolutionary Biology, could challenge the way scientists think about evolution in relation to the position a species holds on the food chain.

Up until now, scientists thought that species that eat a wide variety of different foods might evolve quicker and show more variations in morphology—physical aspects such as size, shape, and color.

However, Borstein and his team were able to prove the exact opposite: species with the most limited diet are evolving faster.

For the study, the researchers produced an evolutionary "family tree" that describes the relationships of more than 1,500 coral reef species, their place in the food chain, and the diversity of items on which they feed.

They also digitized hundreds of photographs of reef fish to gather information on physical traits that are important for feeding, such as the depth of the peduncle (the part of the fish where body and fins attach).

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Mountain lions often lose to wolves and bears, study finds

by Shreya Dasgupta on 6 February 2018

When the hunting grounds of pumas overlap with those of other top predators, such as wolves, bears and jaguars, pumas are often the losers, a new study has found.

The findings from the study, a review of existing scientific literature, are especially important given how pumas are still being intensively hunted over much of their range in a bid to reduce conflicts with people and livestock, researchers say.

In some puma habitats where wolves and brown bears are recolonizing and recovering, wildlife managers need to be cautious about hunting limits for pumas, the authors write.

The large, secretive puma (Puma concolor) may be at the top of its food chain, but it is not always the king of its territory.

Native to the Americas, the puma, also called the mountain lion, cougar, catamount or panther, often shares its habitat with several other top predators, such as wolves, bears, coyotes and jaguars. But when the hunting grounds of these predators overlap, the puma is often the loser, researchers report in a new study published in PeerJ.

By reviewing the scientific literature on competition between pumas and other predators, researchers have found that wolves, grizzly bears, black bears and jaguars often dominate pumas. In fact, pumas are subordinate to at least one other top carnivore in 47.5 percent of their range across North and South America. In turn, pumas seem to be dominant only over coyotes and maned wolves.

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Snake eats lizard eats beetle: Fossil food chain from the Messel Pit examined

Date: September 7, 2016

Source: Senckenberg Research Institute and Natural History Museum

In cooperation with CONICET in Argentina, Senckenberg scientists examined a spectacular discovery from the UNESCO World Heritage site Messel Pit: A fossil snake in whose stomach a lizard can be seen, which in turn had consumed a beetle. The discovery of the approximately 48-million-year-old tripartite fossil food chain is unique for Messel; worldwide, only one single comparable piece exists. The study was recently published in Senckenberg's scientific journal Palaeobiodiversity and Palaeoenvironments.

It is no secret that the Messel Pit is home to a plethora of fantastic fossils -- but some of the findings are so sensational that they even awe veteran Messel researchers. "In the year 2009, we were able to recover a plate from the pit that shows an almost fully preserved snake," says Dr. Krister Smith of the Department for Messel Research at the Senckenberg Research Institute in Frankfurt, and he continues, "And as if this was not enough, we discovered a fossilized lizard inside the snake, which in turn contained a fossilized beetle in its innards!"

Fossil food chains are extremely rarely preserved; due to the excellent level of preservation at the fossil site, leaves and grapes from the stomach of a prehistoric horse, pollen grains in a bird's intestinal tract and remains of insects in fossilized fish excrements had previously been discovered at Messel. "However, until now, we had never found a tripartite food chain -- this is a first for Messel!" exclaims Smith elatedly. To this day, only one other example of such fossil preservation has been found worldwide -- in a 280-million-year-old shark.

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Illegal drugs are changing the basis of the food chain in rivers

‘As society continues to grapple with aging wastewater infrastructure and escalating pharmaceutical and illicit drug use, we need to consider collateral damages to our freshwater resources’

Ian Johnston Science Correspondent 

People are flushing so many illegal drugs down the toilet that they are altering the natural world.

Researchers tested streams in Baltimore in the US and discovered “numerous drugs” at six different sites, even in forested areas nearby.

They then used an artificial waterway created in a laboratory to test what effect the concentrations of amphetamines found in the streams were having on plants and aquatic animals.

Their findings, they said, were "concerning".

The primary production of biofilm – slime found in most rivers that forms the base of the food chain – was 85 per cent lower in the artificial stream polluted with amphetamines, also known as speed.

And the composition of bacteria also changed and aquatic insects emerged earlier.

Researcher Dr Sylvia Lee, of the US Environmental Protection Agency, warned similar effects were likely to be found elsewhere.

“Around the world, treated and untreated wastewater entering surface waters contains pharmaceuticals and illicit drugs that originate from human consumption and excretion, manufacturing processes, or improper disposal,” she said.

“We were interested in revealing how amphetamine exposure influences the small plants and animals that play a large role in regulating the health of streams.”

The study, which was detailed in the journal Environmental Science & Technology, is one of the first to look into the effects of recreational drugs on nature. Amphetamine is also used in drugs to treat conditions like attention-deficit hyperactivity disorder.

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Shift in Arabia sea plankton may threaten fisheries: Growing 'dead zone' could short-circuit food chain

A growing "dead zone" in the middle of the Arabian Sea has allowed plankton uniquely suited to low-oxygen water to take over the base of the food chain. Their rise to dominance over the last decade could be disastrous for the predator fish that sustain 120 million people living on the sea's edge.

Scientists at Columbia University's Lamont-Doherty Earth Observatory and their colleagues are the first to document the rapid rise of green Noctiluca scintillans, an unusual dinoflagellate that eats other plankton and draws energy from the sun via microscopic algae living within its cells. Noctiluca's thick blooms color the Arabian Sea an emerald green each winter, from the shores of Oman on the west, to India and Pakistan on the east.

In a study published this week in Nature Communications, the researchers show how the millions of green algae living within Noctiluca's cells allow it to exploit an oxygen-starved dead zone the size of Texas. They hypothesize that a tide of nutrient-rich sewage flowing from booming cities on the Arabian Sea is expanding the dead zone and feeding Noctiluca's growth.

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Changing food source bodes ill for whales, cod

By Doug Fraser

dfraser@capecodonline.com

November 25, 2013

WOODS HOLE — A marine ecosystem expert is warning that the effect of changes in water temperature and plankton blooms may have ripple effects up the food chain.

"We believe that the changes in the timing of warming events have affected plant and animal reproduction," wrote oceanographer Kevin Friedland of the Northeast Fisheries Science Center in Woods Hole in an ecosystem advisory released last week.

Read more ...

Top Predators Have Sway Over Climate

Feb. 17, 2013 — University of British Columbia researchers have found that when the animals at the top of the food chain are removed, freshwater ecosystems emit a lot more carbon dioxide into the atmosphere.

"Predators are disappearing from our ecosystems at alarming rates because of hunting and fishing pressure and because of human induced changes to their habitats," says Trisha Atwood, a PhD candidate in the Department of Forest and Conservation Sciences in the Faculty of Forestry at UBC.

For their study, published February 19 in the journal Nature Geoscience, Atwood and her colleagues wanted to measure the role predators play in regulating carbon emissions to better understand the consequences of losing these animals.

Predators are bigger animals at the top of the food chain and their diets are composed of all the smaller animals and plants in the ecosystem, either directly or indirectly. As a result, the number of predators in an ecosystem regulates the numbers of all the plants and animals lower in the food chain. It's these smaller animals and plants that play a big role in sequestering or emitting carbon.

When Atwood and her colleagues removed all the predators from three controlled freshwater ecosystems, 93 per cent more carbon dioxide was released into the atmosphere.

Continued:  http://www.sciencedaily.com/releases/2013/02/130219091014.htm

The sea as a rubbish tip – Microplastic being absorbed by marine life

Biologists prepare guidelines for a more precise investigation into marine pollution from microplastic particles

April 2012. Large quantities of globally produced plastics end up in the oceans where they represent a growing risk. Above all very small objects, so-called microplastic particles, are endangering the lives of the many sea creatures. An estimate of how greatly the oceans are polluted with microplastic particles has so far failed in the absence of globally comparable methods of investigation and data. Together with British and Chilean colleagues, scientists of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association have now analysed all published studies on this topic and have proposed standardised guidelines for the recording and characterisation of microplastic particles in the sea.

Tiny pieces of plastic
Plastic bottles washed on to the beach are as much a part of the coast as the sound of seagulls. What the eye does not see are the innumerable ultra-small plastic objects which float in the water, are washed on to the beach or settle on the sea bed. Scientists refer to these plastic particles as "microplastic particles", understanding these to mean plastic objects whose diameter is less than five millimetres - whereby the majority of microplastic particles are smaller than a grain of sand or the tip of a needle.

It is this property that also makes them so dangerous to the sea dwellers. "Microplastic particles are swallowed by organisms and absorbed via the digestive tract. It has been possible, for example, to detect them in the tissue of mussels or other animals", says Dr. Lars Gutow, biologist at the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. Toxic substances also attach to the small particles in the sea which then enter the food chain in this way and may therefore ultimately be dangerous to humans.

Continued:  http://www.wildlifeextra.com/go/news/ocean-plastic.html