Trophic interactions within high Antarctic shelf communities - Food web structure and the significance of fish

Knowledge about food web structure and trophic relationships is essential for the identification of bottlenecks and vulnerable compartments to estimate ecosystem response to environmental alterations and its impact on overall ecosystem functioning. Fish take a central position in the Southern Ocean food web as they provide a major trophic link between small-sized invertebrates and warm-blooded apex predators. The demersal fish community seems to be resistant to species extinctions and resource fluctuations due to high functional redundancy and a high degree of species' trophic generalism. The pelagic fish community, in contrast, seems to be highly sensitive to any kind of alteration due to species# trophic specialism and low functional compensability. The Antarctic silverfish, Pleuragramma antarcticum, a shoaling zooplankton-feeding pelagic fish, represents an Achilles' heel in the high Antarctic food web.