The food web of Potter Cove (Antarctica): complexity, structure and function

Marina T. I., Salinas V., Cordone G., Campana G., Moreira M. E., Deregibus D., Torre L., Sahade R., Tatián M., Barrera Oro E., De Troch M., Doyle S., Quartino M. L., Saravia L., Momo F. R. (2016) The food web of Potter Cove (Antarctica): complexity, structure and function. Preprint available at http://biorxiv.org/content/early/2016/12/27/094557

Abstract

The study of food web structure and complexity are central to better understand ecosystem functioning. A food-web approach includes both species and energy flows among them, providing a natural framework for characterizing species ecological roles and the mechanisms through which biodiversity influences ecosystem dynamics. Here we present for the first time a high-resolution food web for the Potter Cove marine ecosystem (Antarctica). We studied eleven food web properties to analyze network complexity, structure and topology. We found a low linkage density (3.4), connectance (0.04) and omnivory percentage (45), as well as short path length (1.8) and low clustering coefficient (0.08). Furthermore, relating the structure of the web to its dynamics, we found an exponential degree distribution (in- and out-links) suggesting that Potter Cove food web may be fragile if the most connected species got extinct. For two of the three more connected functional groups, competition overlap graphs reflect high trophic interaction between demersal fish and niche specialization according to feeding strategies in amphipods. On the other hand, it can be inferred from the prey overlap graph that multiple energy pathways of carbon flux exist across benthic and pelagic habitats in Potter Cove ecosystem. Although alternative food sources might add robustness to the web, network properties (low linkage density, connectance and omnivory) suggest fragility and potential trophic cascade effects.

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