For some crustaceans in Antarctic waters, it’s like having an older sibling at their side to fight off bullies.
Forests of seaweed armed with powerful chemical weapons protect these shrimplike amphipods by sticking close by, because the algae are filled with a chemical that fish and other predators find foul. The seaweed benefits in return because the amphipods eat competing forms of algae. Some amphipods go even further, by incorporating the algae’s defensive chemicals into their own tissue.
It’s what scientists call a “mutualistic” relationship.
“What’s impressive to me about the Antarctic mutualism is that it is the two major components of the community. It is the seaweeds that form the structure, and the most abundant animals. I call it a community-wide mutualism. I can’t think of another mutualism that is on that scale,” said AAAS Fellow, chemical ecologist and ecophysiologist Chuck Amsler from his office at the University of Alabama at Birmingham.
Amsler studies these mutualistic neighborhoods in the frigid shallow waters near Palmer Station, one of three U.S. permanent research facilities in Antarctica that are maintained by the Office of Polar Programs at the National Science Foundation.
Much of his work involves chemical interactions between organisms. For plants, and for some animals with little or no mobility, the ability to run or swim from a predator is not an option. That’s where their chemical arsenals, and these mutual aid arrangements come into play.
“Understanding what drives chemical diversity is a big question right now in chemical ecology, both in terrestrial and marine environments,” said Amsler.
Studying Antarctic seaweeds involves some demanding fieldwork. Divers on Amsler’s team must be certified scientific divers.
“It is worth the work. It makes them better scientists,” he said. And, it is under water where some of the wonders of this part of the planet reveal themselves.
“At Palmer you think about Antarctica being this desolate place with very little life. And that's true on land. But you dive, and literally there are undersea forests of brown algae, that you can compare to the giant kelp forests in California,” he said. “When you get to deeper water where the seaweeds start to thin out; these enormously rich, dense communities of sponges; and colonial sea squirts; it’s not what anyone would expect looking around on the surface. It is so magnificent.”
While study of chemical defense brings knowledge about organisms in Antarctica, Amsler’s discoveries are just a starting point for other scientists looking at chemical compounds that can help conquer human diseases.
For decades he’s collaborated with fellow UAB researcher marine invertebrate zoologist James McClintock and University of South Florida chemist Bill Baker. Their work on chemical defenses has uncovered information crucial to medical advances for humans. It has included discovery of a compound that is effective against the antibiotic resistant MRSA bacteria, that kills more than 11,000 patients a year.
Amsler has seen many changes in Antarctica since his studies there began.
“Most of the island that Palmer is on is covered by this huge ice piedmont. It has retreated enormously,” he said. That’s led to dramatic changes in wildlife populations. Once abundant Adélie penguins are now much more scarce because of climate change and resulting changes in ice structure.
“The Adélie penguins get nailed a couple ways. One is they are very dependent on the sea ice for their feeding. And sea ice in this part of the peninsula is three months less in duration than it was 30 years ago. The other is they are very hard wired into where they nest and when they nest,” said Amsler.
It’s just the opposite for the more adaptable gentoo penguins, making it easier for them to colonize.
Improvements in technology have made some aspects of polar research much simpler. Amsler says communications is at the top of that list. Back in the 1980s, communication was a ham radio patch; one way communication with researchers back in the states or family members.
“With the guy on the ham radio listening for you to say ‘over.’ So, ‘I love you honey, over.’ he laughed. “And at Palmer, there was a chalkboard you would sign up they’d come and get you; which made it kind of a social event, waiting for your phone call,” he said.
Having internet access now means scientists can stay in touch with their universities, with students, and with colleagues when a research issue needs attention. Without it he says, it would be almost impossible for senior scientists to spend as much time in the field as they’d like.
Maggie and Chuck Amsler at the summit of Amsler Island. | Courtesy of Chuck Amsler
The scientific contributions made by Amsler and his wife, invertebrate zoologist Maggie Amsler, led to an island near Palmer Station being named after them, in recognition of their career contributions in Antarctic marine biology.
“The only reason there was an island there to be named after people of our generation, was, the glacier used to cover all of this. It’s retreated so much that it became an island. It was named for us in 2007. Climate change has its advantages,” he joked.
What is ahead for Antarctic researchers? Amsler says there is a push within the National Science Foundation to gather more data remotely. New tools, such as underwater robots, can add knowledge without the cost or the environmental footprint of a scientist being on site.
Amsler says one experience on a recent trip unexpectedly allowed him to appreciate the magnificence of the underwater environment. While he has done hundreds of polar dives, a stint as an assistant for one of his colleagues allowed him to see his research world with a different lens.
“I did have an epiphany moment," he said. "I was helping a post doc on her project, that involved me lying motionless on the bottom while I was holding this light sensor that was wired to the surface where she was recording light. I was sitting there, looking around. I see all these amphipod everywhere. I have made hundreds of dives in these communities but just that moment of looking around, my face stuck on bottom and having those numbers become this visual memory; all these tiny little animals on all these big plants. How could that not be important?”
[Associated Photo Credit: Kate Schoenrock]
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