In many habitats, competition is the drama, but benefactors set the stage

Jan 29, 2007

Is the world basically good or basically bad? It appears that in the natural world the answer is "basically good." Positive interactions in which plants and animals benefit from association with one another create the basis for many of the world's ecosystems. Coral reefs, kelp forests, marshes, and other familiar habitats can harbor a diversity of life by providing shelter from both harsh conditions and predators.

New experimental work, published in the February American Naturalist by a team of Brown University researchers suggests those positive effects of living habitats are the most important factor in driving the diversity and abundance of organisms in many ecosystems. The team conducted their research with cordgrass and ribbed mussels – two species that form critical habitat along the U.S. Atlantic coastline – because they are similar to other habitat species like corals and kelps but are more easily subjected to experiments in their natural setting.

Cordgrass, which can establish and persist without the aid of other foundation species, facilitates a dense assemblage of inhabitants (e.g., mussels, snails, seaweeds) with roots/rhizomes that stabilize substrate and a dense canopy that baffles waves and provides shade. Within the cordgrass bed community, ribbed mussels further enhance physical conditions and densities of other species (e.g., amphipods, barnacles) by providing crevice space and hard substrate.

"The stage is set by those species that create habitat," said team leader Andrew Altieri, (now at Northeastern University). "The organisms and interactions that occur within the habitat, such as crabs eating snails or annual plants competing with one another, are just players and roles that we see because of that stage." Previously, the tendency was to focus on negative interactions such as predation and competition. That perspective overlooked the fact that many predators, prey, and competitors were themselves dependent on the positive effects, or facilitation, of species such as marsh grass and mussels that create habitat.

And what about situations where a player on the stage has positive effects of its own? "We call that chain of positive effects a 'facilitation cascade'," said Altieri. The researchers suggest that facilitation cascades could be tapped to aid conservation efforts. Restoration of a habitat-forming species could nurture the return of species including other facilitators in an upward spiral. But Altieri cautioned the findings could cut both ways: "It could make an ecosystem more susceptible to collapse because there are more links in the chain to act as Achilles' heels."

Source: University of Chicago

Explore further: Fungus deadly to AIDS patients found to grow on trees

add to favorites email to friend print save as pdf

Related Stories

US clears $2.3 bln Lenovo deal for IBM unit

6 hours ago

IBM said Friday that US authorities had cleared a $2.3 billion deal allowing China-based Lenovo to take over its server unit after a national security review.

Hitchhiking robot charms its way across Canada

6 hours ago

He has dipped his boots in Lake Superior, crashed a wedding and attended an Aboriginal powwow. A talking, bucket-bodied robot has enthralled Canadians since it departed from Halifax last month on a hitchhiking ...

Attack Ebola on a nanoscale

9 hours ago

(Phys.org) —The Ebola virus outbreak in West Africa has claimed more than 900 lives since February and has infected thousands more. Countries such as Nigeria and Liberia have declared health emergencies, ...

Phone snooping via gyroscope to be detailed at Usenix

9 hours ago

Put aside fears of phone microphones and cameras doing eavesdropping mischief for a moment, because there is another sensor that has been flagged. Researchers from Stanford and defense research group at Rafael ...

Recommended for you

Calcium and reproduction go together

2 hours ago

Everyone's heard of the birds and the bees. But that old expression leaves out the flowers that are being fertilized. The fertilization process for flowering plants is particularly complex and requires extensive communication ...

Of bees, mites, and viruses

17 hours ago

Honeybee colonies are dying at alarming rates worldwide. A variety of factors have been proposed to explain their decline, but the exact cause—and how bees can be saved—remains unclear. An article published on August ...

User comments : 0