Impact of Climate Change on the Antarctic Silverfish and Its Consequences for the Antarctic Ecosystem

Pleuragramma antarctica is the dominant forage fish of the coastal Antarctic, exhibiting a circumantarctic distribution and a well documented abundance in all shelf environments, from the high Antarctic Weddell and Ross Sea systems, to the milder waters of the western Antarctic Peninsula (WAP) shelf. Rapid regional warming on the WAP has produced a dichotomy in annual weather patterns between the high Antarctic systems and the WAP, resulting in swiftly rising midwinter air temperatures and fewer sea ice days during the annual winter cycle on the WAP, and little change in the Ross and Weddell Seas. The WAP shelf thus provides a model system for examining the potential effects of climate warming on an important Antarctic species. Pleuragramma’s life history is characterized by slow growth, late maturity, a high reproductive investment and an association with coastal sea ice for spawning and larval development. All those features will allow the species to weather episodic annual failures in recruitment, but not long term change. Most effects of the increasing temperature associated with climate change will be indirect ones, as temperatures will not increase to the point where they are physiologically life-threatening in the short term. A recent survey of Pleuragramma distribution on the WAP shelf revealed a large break in its historical distribution in shelf waters, suggesting a collapse in the local population of silverfish there. The break occurred in the area that has been most heavily impacted by rapid regional warming: the northern mid-shelf including Anvers and Renaud Island. It may be that the multi-faceted effects of climate change are already at work in its local disappearance