An elementary school science activity asks children who have each been assigned a wetland plant or animal to connect themselves with string and tape to other "organisms" their assigned plant or animal interacts with in some way.
Once an ecosystem web has been created, the teacher describes an event that affects one "organism." That "organism" tugs on its string. Other "organisms" that feel the tug then tug on their strings in turn.
The lesson is that every organism is important to the health and balance of a wetland and that every organism in the wetland is connected to every other organism in some way.
That's more or less an article of faith among ecologists, but how true is it really? Ecologists rarely have the time or resources to test this foundational concept through experiment.
Now a summer-long study shows that the flowering invasive plant purple loosestrife (Lythrum salicaria) triggers a chain of interactions that ultimately alters the diversity of zooplankton populations in artificial ponds.
The interactions cross traditional ecosystem boundaries, connecting aquatic to terrestrial systems on the wings of dragonflies that exploit, at different times in their lives, the resources of both the water and the land.
"It's easy to say that everything is connected in some way, but how much these connections matter is something that we don't always know," says Kevin G. Smith, PhD, adjunct professor of biology in Arts & Sciences at Washington University in St. Louis and associate director of the Tyson Research Center, WUSTL's 2,000-acre field station.
By verifying one of the foundational ideas of ecology, the experiment, published electronically May 24 by the journal Oecologia in advance of print, will help inform decisions about biological control of invasive species, restoration of degraded habitats and similar ecological issues.
A study long meditated
Smith says the
|Contact: Diana Lutz|
Washington University in St. Louis