WASHINGTON -- Even "minor" species can throw whole ecosystems out of whack and subtle changes can trigger large disruptions, researchers reported Friday.
Two reports published this week show that ecological systems are much more delicate than anyone ever thought.In one, Eric Berlow or Oregon State University and colleagues found that species believed to be of little significance could in fact be key to holding ecosystems together.
Writing in the journal Nature, they said they examined the dog whelk, a marine snail that eats mussels and barnacles.
Berlow, who is now at the University of California at Berkeley, found that sometimes the whelks had a stronger effect on mussel populations when they did not heavily attack them.
"The effects were visually dramatic," Berlow said in a statement.
In some cases, the whelks actually helped out the mussels by attacking barnacles, forcing the barnacles to attach themselves more strongly to rocks and thus creating a more stable home for the mussels, too.
Adding more whelks to a plot full of mussels did not necessarily mean more mussels were eaten, he reported.
In fact, he found, weak predation had more of an effect than when the whelks overwhelmingly hunted mussels.
"Our tendency is to focus research and management efforts on species that have consistent, dramatic impacts on an ecosystem," he said.
In a second report, published on Friday in the journal Science, Oregon State University ecologist Eric Sanford experimented with the ochre seastar, which eats and controls the California mussel.
His team found that just a small change in sea temperature -- only 3 degrees Celsius colder than usual -- caused the seastars to eat many fewer mussels than usual.
The colder water is brought by upwelling, which becomes more common during El Nino events -- the cyclical changes in Pacific waters that affect weather around the world -- Sanford said.
"As we consider the impacts of global warming, many people assume the effects will be gradual, a shift to new regions by various plant and animal species," he said.
"But this study shows that if you have an important species which is highly sensitive to temperature, then the effects of small temperature changes on an ecosystem can be amplified by species interactions."