Effects of human exploitation on apex predators and the structure of the food web of the Argentine Sea over the past 6000 years (DEPREMAR)

Alejandro Aguilar Vila, Lluis Cardona Pascual, Enrique Alberto Crespo, Silvana Laura Dans, Mariana Degrati, Néstor Aníbal García, María Florencia Grandi, Susana Noemí Pedraza, Florencia Borella, Julieta Gómez Otero, Patricia Alejandra Gandini, Rocio Loizaga de Castro, Matias Javier Klaich, Massimiliano Drago.

While some species, like the South American sea lion, seem to be recovering demographically now their exploitation has ceased, others, like the South American fur seal, are still categorized as rare species, while the Magallanes penguin has apparently increased in abundance. This suggests that the sequential exploitation of the Sea’s marine resources over the last three hundred years has brought about a shift in ecosystem structure.

The project’s overall goal is to study the changes occurring over the centuries in the ecosystem’s trophic structure by analyzing the isotopic signal of current and sub-fossil material from the above species and from mollusks, in order to track changes in food pyramids and ecosystem structure. Samples will be drawn from three Argentine coastal regions and will date from three different periods: a) from 6000 years ago to the European colonization, b) from the colonization to the start of the 20th century and c) from the start of the 20th century to the present day. These data will allow us to analyze the take-up of trophic resources by apex predators in different time periods and to associate changes in the same with changes in their abundance.