Abstract
The extent, duration, and seasonality of sea ice and glacial discharge strongly influence Antarctic marine ecosystems. Most organisms' life cycles in this region are attuned to ice seasonality. The annual retreat and melting of sea ice in the austral spring stratifies the upper ocean, triggering large phytoplankton blooms. The magnitude of the blooms is proportional to the winter extent of ice cover, which can act as a barrier to wind mixing. Antarctic krill, one of the most abundant metazoan populations on Earth, consume phytoplankton blooms dominated by large diatoms. Krill, in turn, support a large biomass of predators, including penguins, seals, and whales. Human activity has altered even these remote ecosystems. The western Antarctic Peninsula region has warmed by 7°C over the past 50 years, and sea ice duration has declined by almost 100 days since 1978, causing a decrease in phytoplankton productivity in the northern peninsula region. Besides climate change, Antarctic marine systems have been greatly altered by harvesting of the great whales and now krill. It is unclear to what extent the ecosystems we observe today differ from the pristine state.
Highlights
The western Antarctic Peninsula region has warmed by 7°C over the past 50 years, and sea ice duration has declined by almost 100 days since 1978, causing a decrease in phytoplankton productivity in the northern peninsula region
Antarctic marine systems have been greatly altered by harvesting of the great whales and krill
We describe the physical setting, ocean environment, and ecological structure and dynamics of the western Antarctic Peninsula (WAP) coastal region based on research by Palmer Long Term Ecological Research (PAL) (Ducklow et al, 2012) and the British Antarctic Survey (BAS) (Meredith et al, 2004; Clarke et al, 2007)
Summary
The extent, duration, and seasonality of sea ice and glacial discharge strongly influence Antarctic marine ecosystems. The western Antarctic Peninsula region has warmed by 7°C over the past 50 years, and sea ice duration has declined by almost 100 days since 1978, causing a decrease in phytoplankton productivity in the northern peninsula region. The WAP region is distinctive among Antarctic regions, with its north-south geography and direct exposure to the prevailing westerly atmospheric and oceanic circulation It is distinct in its response to climate change, with strong sea ice decreases and rapid winter warming observed over the last three to five decades. In common with most of the world’s coastal regions, the WAP system is profoundly affected by anthropogenic influences, including climate change, pollution, past exploitation of upper trophic level species such as whales and seals, and current exploitation of fish and krill stocks. With a strong focus on Euphausia superba, the Antarctic krill, these studies formed the foundation of all subsequent research in the region and, throughout the Meteoric water (%)
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