Geoscience Reference
In-Depth Information
B. Functional Consumer Classification of the Weddell Sea Food Web
194
C. Extinction Scenarios and Robustness of the Weddell
Sea Food Web . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
197
IV. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
198
A.
Implications of This Study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
198
B. The Weddell Sea Food Web and Functional Consumer
Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
200
C. Extinction Scenarios the Robustness of the Weddell Sea Food Web
203
V. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
205
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
206
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
206
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
216
ABSTRACT
Human-induced habitat destruction, overexploitation, introduction of alien
species and climate change are causing species to go extinct at unprecedented
rates, from local to global scales. There are growing concerns that these kinds
of disturbances alter important functions of ecosystems. Our current under-
standing is that key parameters of a community (e.g. its functional diversity,
species composition, and presence/absence of vulnerable species) reflect an
ecological network's ability to resist or rebound from change in response to
pressures and disturbances, such as species loss. If the food web structure is
relatively simple, we can analyse the roles of different species interactions in
determining how environmental impacts translate into species loss. However,
when ecosystems harbour species-rich communities, as is the case in most
natural systems, then the complex network of ecological interactions makes
it a far more challenging task to perceive how species' functional roles
influence the consequences of species loss. One approach to deal with such
complexity is to focus on the functional traits of species in order to identify
their respective roles: for instance, large species seem to be more susceptible
to extinction than smaller species. Here, we introduce and analyse the marine
food web from the high Antarctic Weddell Sea Shelf to illustrate the role of
species traits in relation to network robustness of this complex food web. Our
approach was threefold: firstly, we applied a new classification system to all
species, grouping them by traits other than body size; secondly, we tested the
relationship between body size and food web parameters within and across
these groups and finally, we calculated food web robustness. We addressed
questions regarding (i) patterns of species functional/trophic roles, (ii) rela-
tionships between species functional roles and body size and (iii) the role of
species body size in terms of network robustness. Our results show that when
