Food Web Topology Associated with the Patagonian Shelf-Break Front

This chapter provides a summary of trophic interactions within the Patagonian Shelf-break Front (PSBF) ecosystem under the food web conceptual framework. We collected the published diet information of the organisms inhabiting the PSBF and constructed the trophic interaction network. We considered 55 trophic species (i.e., phytoplankton, POM and debris as basal species, 19 species/groups of invertebrates, 23 species of fish, 7 sea birds, and 2 marine mammals) with 342 links among them. The connectance of the PSBF food web was 0.11 and the maximum trophic levels was 4.7 for the elephant seal. A pelagic and a benthic pathway were detected in the PSBF, with large demersal generalist fish species (e.g., Argentine hake, long tail hake), and top predators (e.g., elephant seals) playing an important role linking both pathways. The analysis reveals gaps in knowledge, particularly regarding interactions involving basal species and microorganisms with early life stages of fishes and invertebrates. The PSBF food web is dynamic, influenced by spatial and temporal variability in the encounters between species, given their movements and diet shifts during their life cycles. Understanding the food web dynamic and functioning is crucial for predicting the impact of human activities, and the topological description is a first step toward that goal.