Virginia Institute of Marine Science
Understanding the mechanisms by which climate variability affects multiple trophic levels in food webs is essential for determining ecosystem responses to climate change. Here we use over two decades of data collected by the Palmer Long Term Ecological Research program (PAL-LTER) to determine how large-scale climate and local physical forcing affect phytoplankton, zooplankton and an apex predator along the West Antarctic Peninsula (WAP). We show that positive anomalies in chlorophyll-a (chl-a) at Palmer Station, occurring every 4-6 years, are constrained by physical processes in the preceding winter/spring and a negative phase of the Southern Annular Mode (SAM). Favorable conditions for phytoplankton included increased winter ice extent and duration, reduced spring/summer winds, and increased water column stability via enhanced salinity-driven density gradients. Years of positive chl-a anomalies are associated with the initiation of a robust krill cohort the following summer, which is evident in Adelie penguin diets, thus demonstrating tight trophic coupling. Projected climate change in this region may have a significant, negative impact on phytoplankton biomass, krill recruitment and upper trophic level predators in this coastal Antarctic ecosystem.
KRILL EUPHAUSIA-SUPERBA; SOUTHERN ANNULAR MODE; CLIMATE-CHANGE; SEA-ICE; MARINE ECOSYSTEM; VARIABILITY; PHYTOPLANKTON; DISTRIBUTIONS; OCEAN; RECRUITMENT
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We thank Raytheon Polar Services and Lockheed Martin, the captain and crew of the R.V. Laurence M. Gould, and the Palmer Station crew for field assistance. We also acknowledge the many current and former PAL-LTER team members for their assistance with field sampling and processing and analysing samples. We thank Simon Wright and Udi Zelzion for assistance with CHEMTAX and data analysis, respectively. The research was supported by the LTER Program of the US National Science Foundation (ANT-0823101). Data from the PAL-LTER data repository were supported by Office of Polar Programs, NSF Grants OPP-9011927, OPP-9632763 and OPP-0217282.
Saba, Grace K.; Fraser, William R.; Saba, Vincent S.; Iannuzzi, Richard A.; Coleman, Kaycee E.; Doney, Scott C.; Ducklow, Hugh W.; Martinson, Douglas G.; Miles, Travis N.; Patterson-Fraser, Donna L.; Stammerjohn, Sharon E.; and Steinberg, Deborah K., Winter and spring controls on the summer food web of the coastal West Antarctic Peninsula (2014). NATURE COMMUNICATIONS, 5.