The continental shelf off the Western Antarctic Peninsula is our study site. We are spending 36 days at sea to better understand “regional climate warming.”
I want to clarify something very important before I move on: It is “warming” here in this part of the Antarctic but it is “cooling” in other places. There are both warming and cooling temperature changes occurring around our planet, it depends on where you are geographically.
We have a smorgasbord of scientists on board working as a group to try and make sense of how the warming in this region is changing the ecosystem (by the way, it is the most rapid warming of any place on the planet). I will start with why this region is warming. In a nutshell, if that’s possible, the deep ocean water is between 2-4°C (35-39°F). This mass of water is warmer than the surface water in the Antarctic Peninsula which is usually between -1.8°C (29°F), the temperature at which seawater freezes, to 2°C (-35°F) depending on the season. There has been an increase in the force and regularity of winds that come from the west (the ‘ole Westerlies for the sailors types that are reading). The wind drives the warm water from the deep ocean up to the surface. This melts sea ice and glaciers; these melted waters end up in the ocean and change the dynamic life living there. How? Well, I will start small and go big in terms of the organisms we are studying on this expedition. Please note that there are always exceptions in science, including the info below!
Bacteria (single celled organisms that you need a microscope to visualize)
Bacteria need food to survive and those studied on this cruise in the Western Antarctic Peninsula rely on carbon coming from dead matter and poop from other organisms as their food source. This comes from the phytoplankton and zooplankton that live in the ocean (you will learn more about them below!). The bacteria respond to the amount of phytoplankton present. At this point, there is no apparent relationship established for bacteria and regional warming but there will be some added data from this expedition to know more about what microbes are present and what they are potentially doing metabolically.
Phytoplankton (small plants living in the open ocean water)
In the northern parts of the peninsula, there has been a shift of phytoplankton to growth of smaller phytoplankton and a decrease in their numbers. Why? In part, this is due to more cloud cover and less light for growth of phytoplankton.
Zooplankton (small animals living in the open ocean water that can’t swim against ocean currents).
Zooplankton community structure is changing along the Antarctic Peninsula. Some of the shifts include a decrease in the number of krill and an increase in the numbers of salps (gelatinous organisms). Zooplankton play a major role in deposition of carbon from the surface of the ocean to deeper depths through their poop! Poop is heavy and so it sinks. This is important because the carbon that sinks is stored away from the atmosphere, partially relieving the greenhouse effect.
Penguins eat krill and small fish. Krill (see picture right) prefer to eat the large phytoplankton (remember that the numbers of large phytoplankton is decreasing as mentioned above). Because there is less preferable food for the krill, their abundance is declining. Fewer krill means less food for the penguins. Penguins also rely on winter sea ice cover to use as a refuge from predators and as a platform to find food. There is a decrease in winter sea ice and krill from North to South on the Antarctic Peninsula hence the decrease penguin populations.
The whaling group is monitoring the numbers (through visual surveys) of marine mammals in the Western Antarctic Peninsula with a focus on Humpback whales. Using a small boat and a crossbow with a skin sampling “bullet” they have been collecting biopsy samples to better understand the diet, sex, and identification of the whales. This, in the long term, will potentially help explain how regional warming from the North to the South is affecting the marine mammal population.
You may have picked up on a trend, all the biological oceanographers on board are trying to determine how their organisms of interest are affected by the warming of the water in the Western Antarctic Peninsula. How does the community structure change and how are those changes affecting the ecosystem? Putting a team of scientists together on a ship 24 hours a day for 36 days lends itself to an immersed learning environment. We eat, sleep, and live our lives together saturated in science. I often argue that oceanographers are the most progressive scientists because of their time spent as sailors sharing key scientific information with one another. They know their own science as well as their colleague’s science. When is the last time you spent 36 days straight with another department at your work place finding out what they do and sharing their results? It yields answers to big questions about our planet and how she is adjusting to change.
1. Map WAP: Red box indicates our location during the Long Term Ecological Research on the ARSV Laurence M. Gould. The grid indicates our sampling locations throughout the expedition.
2. SEA90007 (image by Emelia DeForce): The Western Antarctic Peninsula
3. Krill picture (image by Chris Linder): Krill are zooplankton and are a key food source for marine animals in the Western Antarctic Peninsula.
4. Whale’s tail (image by David Johnston): Surveying for Humpbacks close to Anver’s Island, Western Antarctic Peninsula
5. Cameron_penguin (image below by Jennifer Mannas): Cameron Rutt holds a juvenile Adelie penguin for measurements on Avian Island, Antarctica