Penguin Dynamics Along the West Antarctic Peninsula

This activity incorporates the use of real scientific data to explore ecosystem dynamics among three Antarctic penguin species. Students will analyze two Long-Term Ecological Research (LTER) data sets and supporting graphics to cause and effect and feedback relationships driving changes observed in Adelie, Chinstrap, and Gentoo penguins between 1975 and 2010 along the West Antarctic Peninsula. The penguin population datasets were collected from the Palmer Station Study region, which is part of the Long-Term Ecological Research program. The LTER program began in 1974 and has been collecting annual data in this region (as well as numerous other regions in Antarctica) on a variety of ecological interactions. short and long-term penguin changes three dataset to analyze the relationship between climate change, the Antarctic web, and penguin population dynamics.


INTRODUCTION
Scientists have been collecting Long-Term Ecological Research (LTER) Data along the West Antarctic Peninsula (WAP) a nnually since 1974. 1 The Palmer LTER project is one of 26 LTER sites that are also found throughout the U.S., Puerto Rico, and Tahiti. Palmer LTER is focused along the West Antarctic Peninsula and based out of the Palmer Station on Anvers Island (-64.77417*S, -64.05450*W). 1 The information generated from decades of annual data collection has allowed scientists to observe short and long-term penguin population changes in the ecological dynamics along the WAP. This activity focuses on the changes observed between 1975 and 2010 in the population dynamics between three species of penguins found along the WAP: Adelie, Chinstrap, and Gentoo. The impact of changing ocean temperatures along the West Antarctic Peninsula is also investigated using a second LTER dataset to analyze the relationship between climate change, the Antarctic food web, and penguin population dynamics.

A CLOSER LOOK AT THE PROBLEM
The Percent of Penguin Population data (see Figure 1) reveals an 85% decline in Adelie penguin populations along the Palmer Station study region while Chinstrap and Gentoo penguin populations are on the rise. Facilitating a class discussion encourages possible causes for the changes observed in the data. Student concerns relevant to climate change, sea-level rise, and predator-prey relationships are addressed using a series of graphics that address each area of concern. Allowing students to work in teams facilitates open discussions as they make interpretations and inferences based on each graphic. The Student Lab Sheet (see online access link on page 28) provides space for observations of each data set and for each of the graphics.
Adelie penguins are far more dependent on sea ice than are Chinstrap or Gentoo penguins. The latter two species prefer nesting sites along rocky outcrops that are free of ice. Annual sea ice has continued to decline with changes in climate and sea surface temperatures. Sea ice forms when ice freezes at the surface. Sea ice is responsible for increasing the Southern Continent's frozen surface area by 14-16 square kilometers (5-6 square miles) during the winter months 3 (Figure 6).

West Antarctic Peninsula Analysis
It is important to differentiate between the decrease in the sea ice season observed along the West Antarctic Peninsula as compared to the remainder of the Southern Continent ( Figure 7). Increases in annual sea ice have been recorded in the regions south of the peninsula and throughout East Antarctica. 4 Scientists are continuing to research the discrepancies observed between East Antarctica and the West Antarctic Peninsula sea ice to define the key variables driving this variance.

Antarctic Food Web Analysis
Large predators such as penguins, seals, and whales characterize the marine food web along the west Antarctic Peninsula. (See figures of Antarctic food webs online at http://pal.lternet.edu/research/transformational-science and http://polardiscovery.whoi.edu/antarctica/ecosystem.html.) This aquatic food web is sustained by upwelling that supports high productivity and large krill populations. 6 The base of this aquatic food web is the algae that grows beneath the sea ice and supports the plethora of microfauna that the krill (Euphausia superba) feed upon, from diatoms to copepods. As a result, krill are highly dependent on sea ice for survival in their first year. 7 Increases in sea ice yield increases in algae (phytoplankton) growth, which raises the productivity to support krill growth and survival. Sea ice reduction lowers productivity and reduces the biomass of krill along the West Antarctic Peninsula.

Adelie Penguin Diet Graph Analysis
Why does the decline in sea ice impact Adelie penguins and not the Chinstrap and Gentoo penguins? The previous analysis of the Antarctic food web reveals the key role krill play in penguin diets. This section looks at the diet composition of Adelie penguins using real data collected at PAL-LTER between 1992 and 2015. A step-by-step tutorial is provided to assist students in accessing real data from the Palmer LTER portal (see online access link on page 28).
Students will generate a pie graph to illustrate the Adelie penguins diet composition, which is comprised predominantly of two species of krill (Thysanoessa macrura; Euphausia superba). Chinstrap and Gentoo diets also include krill. In addition, Gentoo penguins also forage on small fishes and squid. 9 Their food resources are not sea ice-dependent species and can be found in many regions along the West Antarctic Peninsula. The dietary restrictions of the Adelie penguins create a more sea ice-dependent species.

PULLING IT ALL TOGETHER
This activity allows students to explore the interdependency between climate change, sea ice, and the Antarctic food web along the West Antarctic Peninsula. The diet composition of Adelie penguins is predominantly two species of krill; whereas, Chinstrap and Gentoo penguin diets are more diverse and less sea ice-dependent. Changes in annual sea ice are decreasing along the West Antarctic Peninsula, whereas, other regions of the Southern Continent continue to show increases in annual sea ice. Less accumulation of sea ice in the study region is creating a decline in productivity leading to reductions in krill concentration. This reduction in krill for this region presents a burden for Adelie penguin populations, requiring greater energy expenditures in search of a scarcer food source. As a result, Adelie penguin populations have been observed moving farther south along cooler peninsula regions harboring more sea ice. 10 The plight of the Adelie, Chinstrap, and Gentoo penguin population dynamics is marked by the displacement of the Adelie population as the Chinstrap and Gentoo populations adapt to environmental changes impacting the West Antarctic Peninsula's ecosystem. Reductions in sea ice conditions have increased available nesting sites for Chinstrap and Gentoo species, which are less sea ice-dependent than Adelie penguins. This activity demonstrates how competition and predator-prey relationships drive evolution processes as each species strives to adapt to changes in the environment around them. MIRIAM SUTTON is a former classroom science educator who now provides education, communication, and outreach to academic and general audiences while assisting research institutions with broader impacts through her 501c3 organization, Science by the Sea®.

Comparison of Classroom Data Distribution for Graphing Activity
Single Species Data Set STEP 1a: Pairs/Teams of students generate an Adelie Penguin Graph STEP 1b: Pairs/Teams of students generate a Chinstrap Penguin Graph STEP 1c: Pairs/Teams of students generate a Gentoo Penguin Graph STEP 2: Each team analyzes their single species graph and draws their conclusion based solely on their single species STEP 3: Each team presents their findings of their single penguin species to the class for comparison and discussion Note: The "blind study" technique used with the Single Species Data Set provides an easier graphing exercise for younger students and also generates a livelier discussion among students as each team discovers the positive and negative variance revealed in the separate datasets.
Composite Species Data Set STEP 1: Pairs/Teams of students generate a single graph of the three penguin species STEP 2: Each team analyzes their composite species graph and draws their conclusion based on changes observed in each species of penguin STEP 3: Each team presents their findings of their composite species graph to the class for comparison and discussion Note: The Composite Species Data Set method requires less class time to complete once graphing is completed. Students who are unfamiliar with generating three graphs in one chart may find this method challenging.