Food web structure and species’ role in the sub-Antarctic Marine Protected Area Yaganes

Abstract

The Marine Protected Area Yaganes (MPAY) was created in response to the significant deterioration of ecosystems caused by the environmental crisis affecting our planet, with the aim of protecting key ocean habitats and species. Located at the southern tip of South America, MPAY is home to a wide variety of marine biodiversity and habitats, making it of special interest for the conservation of sub-Antarctic environments. For the first time, we described the potential trophic interactions within the MPAY, with a focus on the pelagic realm. We applied both network-level and species-level approaches to characterise the structure and complexity of the food web, aiming to understand trophic dynamics and the specific roles of certain species within it. In terms of complexity, the MPAY food web consists of at least 124 species with 656 predatorprey interactions, a density of interactions of 5.29 and a connectance of 0.04. Regarding its structure, approximately 71% of the species occupy intermediate trophic levels. The Keystone Species Index (KSI) highlighted the importance of some species such as the Patagonian toothfish (Dissostichus eleginoides), the amphipod Themisto gaudichaudii, euphausiids and myctophids, among others, to the structure of the food web. Identifying the relevance of these species lays the groundwork for the effective stewardship of the little-known MPAY, focussing on its conservation.