Unraveling the multiple bottom-up supplies of an Antarctic nearshore benthic community

Abstract

Disentangling the bottom-up controls of natural ecosystems is key to understanding the capacity of local communities to resist natural and anthropogenic disturbances. Here, we used carbon and nitrogen stable isotope ratios with a Bayesian multiple source mixing model to trace diverse food sources supporting the benthic trophic network in Fildes Bay (South Shetland Island, Western Antarctic Peninsula). Individuals of 16 species of consumers and five potential food sources (e.g. inter- and subtidal macroalgae, suspended and sinking particulate organic matter, and particulate organic matter from sediment) were collected during January and February 2017. The results showed that benthic organisms of Fildes Bay assimilate a broad range of available organic matter: most of the energy channeled to upper trophic consumers comes from organic matter in the surface sediment, whereas energy moving among lower trophic consumers comes largely from macroalgae and pelagic primary food sources. Overall, our evidence indicates that the present-day nearshore benthic community of Fildes Bay relies on different primary food sources, channeling bottom-up supplies through multiple pathways, which leads to highly stable systems in the face of current scenarios of global change.