Looking Back in Time Through Marine Ecosystem Space: A Predators Perspective on Climate and Change in the Western Antarctic Peninsula William R. Fraser Polar Oceans Research Group Sheridan, Montana

Outline PAL Space/Time Regional SettingPAL Space/Time Regional Setting Climate Change OverviewClimate Change Overview Geology and Adélie Penguin Population DistributionsGeology and Adélie Penguin Population Distributions Climate Change Effects and Ecosystem ResponseClimate Change Effects and Ecosystem Response Conclusions and Future DirectionsConclusions and Future Directions

The Western Antarctic Peninsula (WAP) The WAP is the only location in Antarctica where the Antarctic Circumpolar Current (ACC) is directly adjacent to the shelf break. The ACC is Antarcticas warmest water. Ross Sea gyre Weddell gyre D. Martinson

PAL Spatial Operational Area and Data Time Series WAP = 220,000 km 2 Anvers Isl Anvers Isl. Palmer Station LTER Grid = 120,000 km 2 LTER Research Top Predator Studies E. Erdman, SO-GLOBEC database

Sampling capitalizes on a nested grid approach by using research platforms that annually operate over large and small scales during the October-March period

Climate Change…surface air and ocean temperatures Meredith & King, 2005 Martinson et al., In Press Coldest Water in January Water Column D. Martinson ˚ C/year Significant at 0.05 ~5.4x global average British Antarctic Survey

Climate Change…sea and glacial ice 83% of glaciers are in retreat Major loss of perennial sea ice cover Duration of the sea ice season has decreased by 85 days during the last 25 years Cook et al Sea Ice Cover S. Stammerjohn Perennial Ice S. Stammerjohn

Breeding Distribution of Adélie Penguin Populations in the Western Antarctic Peninsula Region Photo by H. Geisz, PAL LTER Fraser & Trivelpiece 1996 Hypothesis: The breeding distribution of Adélie penguins is limited to regions where prey availability is predictable over ecological time scales (decades to centuries) Rationale? Adélie penguins are flightless and incapable of foraging at night, which greatly limits the range over which they can search for prey in summer when feeding chicks

Hypothesis Testing: Technological Advances Mapping the oceans floor Miniaturizing satellite-linked instruments to track Adélie penguins at sea

Hypothesis Testing: Geology and Bathymetry The Palmer Deep off Anvers Island ANVERS Is E. Domack

Hypothesis Testing: Bathymetry and Adélie Penguin Foraging Ecology Anvers Island E. Domack

Anvers Is Bathymetry and Adélie Penguin Foraging Ecology: Causal Factors and Larger Scales Primary Production Contour of regions of low pCO 2 (highlighted in red), based on WAP January cruises D. Karl, unpublished Adelaide Is

Anvers Is Bathymetry and Adélie Penguin Foraging Ecology: Causal Factors and Larger Scales Regions of Polynya Formation WINTER 2001 and 2002.

Anvers Is Bathymetry and Adélie Penguin Foraging Ecology: Causal Factors and Larger Scales Importance to Other Predators (Crabeater Seals)

Climate Change Effects and Ecosystem Response 0.107˚ C/year Significant at 0.05 ~5.4x global average Perennial Ice

One of the mechanisms by which climate change induces change in ecosystem structure is by disrupting the evolved life history strategies of component species. Rhodes & Odum 1996 New Paradigm…Climate Migration Key Physical Variables are Changing Along a North to South Gradient Sub-Antarctic Life History Groups are Replacing Antarctic Life History Groups WAP Ecosystem Structure is Changing in Fundamental and Possibly Unprecedented Ways

Key Implication: Ecological changes are due to region specific changes in sea ice as a temperature isotherm migrates north to south Sea ice data courtesy of E. Chapman How is Climate Migration Operating?

Net Average Effects?...Annual Winter Sea Ice no Longer Covers Approximately 50% of the WAP mmmmmm Adelaide Isl. Renaud Isl. Anvers Isl. Palmer Sta. WAP Ecosystem Structure is Changing in Fundamental and Possibly Unprecedented Ways Sub-Antarctic Life History Groups are Replacing Antarctic Life History Groups

North to South Changes in Primary Production (climatology, ) Relative to Penguin Populations M. Vernet

ADELAIDE IS ANVERS IS Statistically significant north to south differences in recruitment frequency and population size structure North to South Changes in Antarctic Krill (Euphausia superba) Populations Atkinson et al A two-fold decrease/decade in krill density

North to South Changes in Antarctic silverfish (Pleuragramma antarctica) Populations ANVERS IS ADELAIDE IS

North to South Changes in Populations of the Lanternfish (Electrona antarctica) ADELAIDE IS Silverfish ANVERS IS Lanternfish

North to South Changes in Stable Isotope Signatures (krill dominated diets at Palmer vs silverfish dominated diets at Avian Is PALMER STA AVIAN IS

North to South Penguin population changes Habitat optimum hypothesis: Too much ice is as detrimental to Adélie penguins as too little ice. Fraser & Trivelpiece 1996, AGU ANVERS IS ADELAIDE IS On Anvers Island chinstrap and gentoo penguins, two sub-Antarctic species, are replacing Adélie penguins

Conclusions and Future Directions Climate migration is having an impact on a range of ecosystem properties, from key physical variables to food web structureClimate migration is having an impact on a range of ecosystem properties, from key physical variables to food web structure Trends indicate that the ice- dependent life history group that once populated the northern sectors of the WAP are being replaced by an ice- intolerant life history group over ecological time scales.Trends indicate that the ice- dependent life history group that once populated the northern sectors of the WAP are being replaced by an ice- intolerant life history group over ecological time scales. Glacially incised, cross shelf canyons are focal points of physical and biological processes affecting WAP ecosystemsGlacially incised, cross shelf canyons are focal points of physical and biological processes affecting WAP ecosystems Future directions…Future directions… Antarctic Circumpolar Current

Future Directions Looking back in time through marine ecosystem space… … by emphasizing changes in sampling strategies that will capture climate migration and provide a more mechanistic understanding of marine ecosystem response