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MEPS prepress abstract   -  DOI:

Trophic structure of southern marine ecosystems: a comparative isotopic analysis from the Beagle Channel to the oceanic Burdwood Bank area under a wasp-waist assumption

Luciana Riccialdelli*, Yamila A. Becker, Nicolás E. Fioramonti, Mónica Torres, Daniel O. Bruno, Andrea Raya Rey, Daniel A. Fernández

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ABSTRACT: Understanding the structure and functioning of marine ecosystems has become a critical issue to assess the potential short- and long-term effects of natural and anthropogenic impacts and to determine the knowledge needed to conduct appropriate conservation actions. This goal can be achieved in part by acquiring more detailed food web information and evaluating the processes that shape food web structure and dynamics. Our main objective was to identify large-scale patterns in the organization of pelagic food webs that can be linked to a wasp-waist (ww) structure, proposed for the southwestern South Atlantic Ocean. Thus, we evaluated three sub-Antarctic marine areas in a regional context: the Beagle Channel (BC), the Atlantic coast of Tierra del Fuego (CA) and the oceanic Burdwood Bank area (BB). We used carbon and nitrogen isotopic information of all functional trophic groups, ranging from primary producers to top predators and analyzed them through stable isotope-based Bayesian analyses. We found that BC and BB have a more pronounced ww-structure compared to CA. Plus, we identified mid- to low-trophic position species that play a key role in the tropho-dynamic of each marine area (e.g., Sprattus fuegensis, Patagonotothen ramsayi and Munida gregaria) and considered them as the most plausible ww-species. The identification of the most influential species within food webs has become a crucial task for conservation purposes in a local and regional context to maintain ecosystem integrity and the supply of ecosystem services for the southwestern South Atlantic Ocean.