Media Release |
Nov. 15, 2004
Ocean’s Mud-dwellers Provide Clues to the Impact Extinction
Can Have on Ecosystems
An international team of scientists, including UBC zoology
professor Diane Srivastava, has discovered that the order
in which species go extinct -- rather than just the number
of species as previously thought -- ultimately determines
long-term impact on an ecosystem.
In a study published in the November 12 issue of the journal
Science, Srivastava and her colleagues provide a new look
at long-term ecosystem impacts by studying the loss of shrimps,
clams, worms and other organisms from the sea floor. Such
bottom-dwelling marine creatures are particularly vulnerable
to extinction because they are often unable to avoid disturbances.
“This represents an important step forward in ecological
thinking,” says Srivastava. “Up to this point,
scientists had only determined the theoretical relationship
between the number of species in an ecosystem and how well
At the bottom of the world’s oceans live an astonishing
array of animals -- crabs, brittlestars and marine worms --
that play an essential role in regulating and recycling the
planet’s resources by churning up and filling the sediments
with oxygen (a process called bioturbation).
In a comprehensive survey of 139 sea floor-dwelling marine
invertebrates in Galway Bay, Ireland, the team looked at how
extensively the sediments are mixed there, matched that with
data on species size, abundance and movement through the mud,
and constructed mathematical models to predict the ecological
consequences of losing species.
They found that the extinction of species is generally expected
to reduce the amount of sediment mixing, and consequently
diminish the oxygen concentrations that sustain life. The
amount of change depends on the order in which species are
going extinct as well as the reasons animals are disappearing.
This suggests that conservation efforts should focus not only
on the seemingly important species, but also on the total
variety of life -- including the sediment-churning bottom
dwellers -- found in an ecosystem.
“These findings tell us that we need to understand
better why and which species are likely to go extinct if we
are predict the practical consequences of their loss. Sustaining
the valuable services provided by our oceans will ultimately
depend on preserving the broad diversity of life that resides
there,” Srivastava says.
Marine coastal ecosystems are among the most productive and
diverse communities on Earth and they play a significant role
in the regulation of climate, nutrients, and the food chain,
but rapid changes in biodiversity -- brought on by human activities
such as overfishing, habitat destruction and pollution --
are occurring says Srivastava, who collaborated with researchers
from the United States and Scotland on the study.
Predicting how coastal environments will cope as animal species
decline as a result of human activity will depend on a better
grasp of why species are at risk and the role they play in
To interview Prof. Srivastava, call 902.434.6437 or contact
Michelle Cook, UBC Public Affairs at 604.822.2048.