The krill-dominated pelagic system of the Southern Ocean

Abstract The krill-dominated pelagic system of the seasonal pack-ice zone of the Antarctic Eastwind Drift and the Weddell Gyre is characterized by high concentrations of phytoplankton and krill (amongst other zooplankton) and warm-blooded top consumers. Krill, birds, and mammals are “giants” with high mobility and energy demands, slow growth, low reproduction, and a long life span. The high standing stock of krill and its consumers and their localised dense concentrations attract exploitation by man, but the low net production makes the system susceptible to overfishing. The system appears to be food limited at the adult stage of krill and its consumers. Fluctuations in abundance occur particularly at the larval phase of krill. The juvenile and adult phases are also subject to substantial spatial variations in abundance which affect any kind of harvesting by top consumers, including man.