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!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences