Diversified feeding strategies of Pleuragramma antarctica (Nototheniidae) in the Southern Ocean

The Antarctic silverfish Pleuragramma antarctica is a plankton feeder playing an important role at midtrophic level in High Antarctic ecosystems. Over years, a reasonable bulk of information has been collected on the trophic ecology of the species, nevertheless there are several aspects that still deserve full elucidation. Here, we explore the trophic plasticity of the Antarctic silverfish, its ability to change and optimize the diet according to the prey availability. A comparative analysis of stomach contents, fish condition, and feeding selectivity was performed on specimens from three different locations in the Southern Ocean: Ross Sea, Adelie Land, and Antarctic Peninsula. While confirming copepods and euphausiids as the most important items in the diet of the Antarctic silverfish, present study revealed significant local differences in diet composition and fish condition. The specimens from the Antarctic Peninsula showed the highest body condition and euphausiids were the preferential prey. Conversely, specimens from the Ross Sea and Adelie Land, where euphausiids are not as abundant as in those of the Antarctic Peninsula waters, showed a flexible and opportunistic trophic habit strategy, profiting of being able to rely on the great variety of planktonic prey. Being P. antarctica a key component of the pelagic ecosystem, improved knowledge of the trophic ecology of this fish would contribute to a throughout understanding of its response to environmental change.