A grasshopper's change in diet to high-energy carbohydrates while being hunted by spiders may affect the way soil releases carbon dioxide into the atmosphere, according to research results published this week in the journal Science.
Grasshoppers' diets while being hunted may affect how soil releases carbon dioxide.
Grasshoppers like to munch on nitrogen-rich grass because it stimulates their growth and reproduction.
But when spiders enter the picture, grasshoppers cope with the stress from fear of predation by shifting to carbohydrate-rich plants, setting in motion dynamic changes to the ecosystem they inhabit, scientists have found.
"Under stressful conditions they go to different parts of the 'grocery store' and choose different foods, changing the makeup of the plant community," said Oswald Schmitz, a co-author of the paper and an ecologist at Yale University.
The high-energy, carbohydrate diet also tilts a grasshopper's body chemistry toward carbon at the expense of nitrogen.
So when a grasshopper dies, its carcass breaks down more slowly, thus depriving the soil of high-quality fertilizer and slowing the decomposition of uneaten plants.
"This study casts a new light on the importance of predation in natural communities," said Saran Twombly, program director in the National Science Foundation's Division of Environmental Biology, which funded the research.
"A clever suite of experiments shows that the dark hand of predation extends all the way from altering what prey eat to the nutrients their decomposing bodies contribute to soil."
Microbes in the soil require a lot of nitrogen to function and to produce the enzymes that break down organic matter.
"It only takes a slight change in the chemical composition of that animal biomass to fundamentally alter how much carbon dioxide the microbial pool is releasing to the atmosphere while it is decomposing plant organic matter," said Schmitz.
"This shows that animals could potentially have huge effects on the global carbon balance because they're changing the way microbes respire organic matter."
The researchers found that the rate at which the organic matter of leaves decomposed increased between 60 percent and 200 percent in stress-free conditions relative to stressed conditions, which they consider "huge."
"Climate and litter quality are considered the main controls on organic-matter decomposition, but we show that aboveground predators change how soil microbes break down organic matter," said Mark Bradford, a co-author of the study and also an ecologist at Yale.
Schmitz added: "What it means is that we're not paying enough attention to the control that animals have over what we view as a classically important process in ecosystem functioning."
The researchers took soil from the field, put it in test tubes and ground up grasshopper carcasses obtained from environments either with or without grasshopper predators.
They then sprinkled the powder atop the soil, where the microbes digested it.
When the grasshopper carcasses were completely decomposed, the researchers added leaf litter and measured the rate of leaf-litter decomposition.
The experiment was then replicated in the field at the Yale Myers Forest in northeastern Connecticut.
"It was a two-stage process where the grasshoppers were used to prime the soil, then we measured the consequences of that priming," said Schmitz.
The effect of animals on ecosystems is disproportionately larger than their biomass would suggest.
"Traditionally people thought that animals had no important role in recycling of organic matter, because their biomass is relatively small compared to the plant material that's entering ecosystems," Schmitz said.
"We need to pay more attention to the role of animals, however. In an era of biodiversity loss we're losing many top predators and larger herbivores from ecosystems."
Other co-authors are Michael Strickland of Yale, and Dror Hawlena of the Hebrew University of Jerusalem.Media Contacts
Cheryl Dybas | EurekAlert!
From Receptor Structure to New Osteoporosis Drugs
20.11.2018 | Universität Zürich
Mutation that causes autism and intellectual disability makes brain less flexible
20.11.2018 | Institute of Science and Technology Austria
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
20.11.2018 | Life Sciences
20.11.2018 | Life Sciences
20.11.2018 | Ecology, The Environment and Conservation