Thanks to Jim Robbins at Yale 360 for this:
In a development that has important implications for conservation, scientists are increasingly focusing not just on what species are present in an ecosystem, but on the roles that certain key species play in shaping their environment.
In 1966, an ecologist at the University of Washington named Robert Paine removed all the ochre starfish from a short stretch of Pacific shoreline on Washington’s Olympic Peninsula. The absence of the predator had a dramatic effect on its ecosystem. In less than a year, a diverse tidal environment collapsed into a monoculture of mussels because the starfish was no longer around to eat them.
By keeping mussel numbers down, the starfish had allowed many other species to thrive, from seaweed to sponges. Paine’s research led to the well-known concept of keystone species: The idea that some species in an ecosystem have prevailing traits — in this case preying on mussels — whose importance is far greater than the dominant traits of other species in that ecosystem.
Now, a half-century later, researchers are taking the study of traits much farther, with some scientists concluding that understanding the function of species can tell us more about ecosystems than knowing which species are present — a concept known as functional diversity. This idea is not merely academic, as scientists say that understanding functional diversity can play an important role in shaping conservation programs to enhance biodiversity and preserve or restore ecosystems.
“The trait perspective is very powerful,” says Jonathan Lefcheck, a researcher at the Bigelow Marine Lab in East Boothbay, Maine who studies functional diversity in marine environments. “Some species in an ecosystem are redundant, and some species are very powerful.”
Much about the concept is also unknown. One case study is taking place along the Mekong River, a 2,700-mile waterway that serves as a vital fishery for millions of people in Southeast Asia. While the fishery is healthy now, widespread changes in the ecosystem — including the proposed construction of numerous dams and the development of riparian forests and wetlands — could mean that key fish species might not be around to carry out important functions, such as keeping prey numbers in check or recycling nutrients.
“There is simply no understanding of how the construction of a dam today, and another five years from now, and another in 10 years — all in the same river basin — will impact the biodiversity and push it past a point of no return, where large scale species extinctions are imminent,” said Leo Saenz, director of eco-hydrology for Conservation International.
So a team of ecologists from Conservation International is trying to determine which roles various species in the Mekong fill that are critical to perpetuating a healthy ecosystem. Those species might be predators like the giant snakehead, which helps control other fish populations so they don’t become too numerous, or thick groves of mangrove forests in shallow areas that provide a nursery for a wide variety of fish species. Models can then predict the best way to protect these key species and ensure a healthy river over the long term…
Read the whole article here.