An Atlas of Marine Species in the Antarctic's Changing Climate

Last week, a group of Antarctic researchers published an atlas of the waters around the world's most southern continent—the "most thorough audit of marine life in the Southern Ocean."

The Biogeographic Atlas of the Southern Ocean set out to collect a large amount of environmental data about the region, not just to create a census of the more than 9,000 species around right now, but to help predict how the changing environment (i.e. climate change) could affect the area in the future.

The book was published by the Scientific Committee on Antarctic Research and drew on contributions from a large group of global experts. On the atlas site, they write that some of the waters studied—to the west of the Antarctic Peninsula—are "warming faster than any other place on Earth."

While the atlas contains many photos of animals cute (penguins) and cool (squid), its 800 maps and diagrams are perhaps best at telling the story of today's marine Antarctic environment and where it's headed in the future.

Huw Griffiths from the British Antarctic Survey, who edited the atlas, shared some of those maps with me and told me more about the project. He explained that, until now, the go-to Antarctic Map was a series published in 1969, and they felt it was time for an update.

"We knew that we knew more than was in the most-cited literature, basically," he said. Nevertheless, scientific knowledge of the Antarctic remains limited. "To me the most interesting thing was finding out what we knew we didn't know about," he added. There are whole areas of the continent where very little data has been collected, such as the deep oceans or areas permanently covered in ice and therefore impossible to get to.

Maps in the atlas showing the sea ice at different times in the year give an idea of how even the basic shape of the continent changes with the seasons. The map below shows the amount of time the Southern Ocean is covered by sea ice—you can see how the mass can grow and shrink.

While changing sea ice and melt levels are an obvious climate change worry around the world, they present specific environmental challenges closer to home. Griffiths said sea ice is not necessarily bad; some of the microscopic plant species like it, as they can cling to it and still get sunlight through the ice (as long as it's not too thick). But if the ice doesn't melt enough, those plants won't fall to other organisms as food.

Sea ice and snow also makes a good habitat for emperor penguins (Aptenodytes forsteri), but not king penguins (Aptenodytes patagonicus), which prefer rocky nesting grounds. "If ice patterns change and bits of the Antarctic Peninsula for instance melt, you might find king penguins take over the habitats that were emperor penguin habitats," said Griffiths. You can see their current distribution below:

Despite the million-plus records in the atlas, it's clear that this latest study is also limited in its scope. In the map below, the red dots show discoveries made in the researchers' immediate area of interest and the blue just outside.

You can see that, around the pale blue area of sea ice, there are fewer records noted—that's not because there aren't species there, but because gaps in our knowledge remain. The best studied areas are naturally those near research bases and shipping routes, given the difficulty and expense it takes to get to the region.

This next diagram shows the numbers of species found in each area around the Antarctic. Again, low numbers don't necessarily mean low populations of organisms. "There's nowhere in the world that would really have only 10 species known from there, so the chances are anything less than the hundreds, we really don't know very much about those areas," said Griffiths.

That's not to say the new atlas didn't make some new discoveries. For instance, the researchers found out that the rather terrifying-looking crustacean Glyptonotus antarcticus, thought to be one species, could actually be a group of 11 different species.

Griffiths said they plan to put each chapter of the atlas online in PDF form in the future, and are gifting copies to research institutes that work on the Antarctic. The ultimate plan is to keep building on the huge compendium of knowledge, but, for now, the atlas is a pretty thorough starting point to build on.