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Anvers Island E. Domack The higher trophic levels The New Program

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slide1

Anvers Island

E. Domack

The higher trophic levels

The New Program

SATELLITES: Over the last decade, satellite observations of Ocean Color (SeaWiFS, and MODIS) Sea-Surface Temperature (AVHRR and MODIS), Sea Ice (MODIS, QuickSCAT) winds (QuickSCAT) are the major data streams for the WAP. These data streams have been used largely for chlorophyll and temperature surveys; however to take advantage of the full ecological information we will apply a newly developed spatially and temporally dynamic water mass mapping algorithm. This algorithm assimilates concomitant passes of ocean color radiance channels and sea surface temperature, then based on bioinformatic clustering algorithms, objectively determines the number and different types of water masses in the area of interest. This approach has been shown to map ocean biomes, and has been particularly effective at tracking coastal water masses (Oliver et al. 2004; Oliver et al. 2008). An initial analysis of the statistically significant satellite derived water masses in the WAP region shows a high degree of variability. These satellite data streams will be combined with 17 year LTER time series.

  • The NASA Biodiversity program is initiating a new program focused on understanding how climate change will impact Antarctic ecosystems. This program leverages off the NSF sponsored LTER Palmer program. The program will combine:
  • - long term time series data of the WAP
  • - active radio-tagged penguins
  • autonomous underwater gliders
  • population modeling and,
  • novel remote sensing approaches for water mass delineation
  • These technologies will provide insight into the physical factors that determine the biological hot spots that determine the zones that define penguin foraging regions along the WAP. This efforts will focus on the ship based sampling grid and process studies conducted at Palmer Station (red circle).

Physics and lower trophic levels

Over the same time period, ice-dependent Adélie penguin (Pygoscelis adeliae) colonies in the northern WAP region (Anvers Island) have undergone drastic population reductions, a decline mirrored by the equally ice-dependent Weddell seals (Leptonychotes weddellii). Ice-avoiding species of penguins (Gentoo, P. papua, and Chinstrap, P. antarctica) and seals (Fur, Arctocephalus gazelle, and Elephant, Mirounga leonina), however, have been rapidly increasing the same region. New, large breeding colonies of Gentoo and Chinstrap penguins now exist within 10-20 km of Palmer Station, thus providing a clear boundary for the current extent of climate migration along the WAP.

The Western Antarctic Peninsula (WAP) is undergoing the most dramatic climate change on Earth, with mid-winter temperatures in particular increasing by 6o C (5.4 times the global average) during the past half century. With this warming, the maritime system of the northern WAP has expanded southward, displacing the cold continental, polar system of the southern WAP. This “climate migration” has produced a cascade of events with significant consequences for the ecosystems along the WAP. For example, in the southern WAP, 87% of the glaciers, the sea ice season has shortened by nearly 90 days and the perennial sea ice is gone.

Gliders: Gliders are autonomous, underwater, robotic vehicles programmed to swim along prescribed tracks in the upper 1000 meters, making ~60 vertical profiles over ~30 km each day. The glider will be configured for shallower depths to focus on the upper 100m of the water column. The distributed sensor suite will characterize the ecosystem’s physical structure (C, T, D), in situ phytoplankton fluorescence and particle backscatter. The shallower working depth will increase the data resolution in the upper water column overlapping the penguin activity. The resolution will be 0.25m in the vertical with a profile every 200m along its track. In addition to the SeaBird CTD, the glider will have two Wet Labs Eco-Triplets providing backscatter at 4 wavelengths (470nm, 532nm, 670nm, and 880nm) as well as two fluorescence channels (Chl-a and CDOM). These in situ optical properties are critical, as Adélie penguins are visual predators.

The changes in the sea ice have resulted in observed changes in the WAP ecosystem. Using three decades of satellite and field data, we have found that the primary productivity has significantly changed along the WAP shelf. Summertime chlorophyll (Chl) (summer integrated Chl is ~63% of the annually integrated Chl) declined by 12% along the WAP over the past 30 years, with the largest decreases equator ward of 63º S and a substantial increase occurring in the south. The latitudinal shift reflect the shifting patterns of ice cover, cloud formation, and windiness affecting water column mixing. Regional changes in phytoplankton coincide with observed changes in krill (Euphausia superba) and penguin populations.

Radio-tagged penguins: Adélie penguins are the focal top predator of the PAL LTER research program, and databases encompass virtually all aspects of their ecology. These databases have already provided significant insights into WAP ecosystem processes ranging from long-term changes in sea ice conditions to Antarctic krill population dynamics. For the purposes of this proposal, field data acquisition will rely on 2 principal methodologies: Instrumentation, Platform Terminal Transmitters (PTTs). During the programs, PTTs will be deployed on Adélie penguins using long-established attachment protocols. Sensors on the PTTs provide foraging location, dive-depth, water temperature, salinity and light level. The data can be retrieved in almost real-time via the ARGOS satellite constellation. The PTTs will be programmed to obtain data that are temporally synoptic with the daily presence of the gliders, thus providing complementary profiles of hot spot physical and biological properties. Programming will include a seasonal switch, meaning that following the departure of the gliders, data acquisition will continue into the autumn but at a reduced rate (sampling every 3 days rather than daily). Autumn is the time of ice formation and is grossly under-sampled as a habitat component in this species. Past experience suggests that for birds instrumented in January, we will obtain data until the March-April period, at which time battery capacity typically expires and/or the PTTs drop off when the birds moult.

100

Night

10

Krill:Salp

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0.1

Investigators discovered that krill and salps were inversely related to each other and that salps dominated warm waters. This resulted in increases in the regions of the warmer water (equator ward of 63º S). These shifts are significant and have profound implications for higher trophic levels. This is because the krill are a key stone food resource for many penguin, whales and seal species.

0.01

0.001

-4

-2

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Mean Air Temperature (°C)

Based on terrestrial and at-sea observations demonstrated that the distribution of Adélie penguins and their prey was extremely heterogeneous, co-occurring spatially and temporally only in regions characterized by a unique combination of deep bathymetry, circulation and upwelling of warmer, nutrient-rich Upper Circumpolar Deep Water. It is only in association with these regions that Adélie penguins breed in summer and forage in winter. The suspected reason is that Adélie penguins are flightless, hence the spatial scales over which they can search for prey are highly constrained. Radio tagged Adelie’s show heavy foraging (white and yellow circles) in the regions at the head of the canyons.

SALP

KRILL

Day

Penguin-Satellite-Glider Studies of Climate Mediated Changes in a Polar Food-Web

Oscar Schofield1, Matt Oliver2, Josh Kohut1, Steven Savard1, Alex Kahl1, Andrew Irwin3, William Frazer4

1: Coastal Ocean Observation Lab, Institute of Marine and Coastal Sciences, School of Environmental and Biological Sciences, Rutgers University2: College of Marine and Earth Studies, University of Delaware 3: Department of Mathematics and Computer Science, Mount Allison University 4: Polar Oceans Research Group

Abstract. We are studying climate change impacts on the ecosystems on the West Antarctic Peninsula (WAP). We will use "top-down” historical time series analysis of existing space-based and in-situ measurements of WAP phytoplankton, krill and penguin distribution and abundance data from the Palmer Long-Term Ecological Research program. Our second approach is a "bottom-up" field program is focused on spatially predicting the foraging locations of the Adélie penguin. This field effort links space-based platforms, AUV's and animal-borne sensors. The results quantify the ability of satellite data streams to capture and describe the climate driven ecological changes in the WAP and predict how Adélie penguin foraging locations and their associated biodiversity.

The new NASA biodiversity efforts

A newly funded NASA Biodiversity program will focus on understanding the physics and biology using a suite of technologies (satellites, gliders, and radio-tagged penguins) to create a coherent 3-D volume of the WAP. These assets will be adjusted adaptively to enable the development of the Generalized Additive Model to determine the relationship between species distributions and abundance, and the satellite predicted pelagic ecosystems.