Compared to most other crustaceans, Antarctic krill aren’t considered large. But in the right company—specifically, other krill species—the shrimp-sized Euphausia superba is the big krill on campus. Far more importantly, Antarctic krill are at the center of the Southern Ocean ecosystem.
A wide array of predators rely heavily on krill in the region. Some penguin species—including Adélies and chinstraps—get almost all their calories from krill. Krill swarms are also a huge draw for baleen whales, such as humpbacks and minkes, that migrate from the tropics to feed in the Southern Ocean. Research shows that humpback and fin whales—whose populations are recovering after centuries of whaling—eat more than 2 million tons of krill combined each year, all from a small region near the Antarctic Peninsula where the commercial krill fishery is increasingly concentrated.
Krill are also a huge, um, draw for marine biologist and cartoonist Jen Walsh. For almost 15 years Walsh, a research biologist with the Antarctic Ecosystem Research Division at the National Oceanic and Atmospheric Administration’s (NOAA), Southwest Fisheries Science Center, has collected krill samples in the Antarctic Peninsula to study how diet, sea ice conditions, population density and abundance, and other environmental variables impact the species.
And through her Instagram account @thescholarlykrill, which she launched in 2020, Walsh entertains and educates her followers on krill science, policy, and more—including August 11, World Krill Day.
This interview has been edited for clarity and length.
Q: What led you to NOAA to study Antarctic krill?
A happy accident! A scientist from NOAA’s U.S. Antarctic Marine Living Resources (AMLR) program was on my committee when I was finishing graduate school in 2008. He needed a technician to go to Antarctica to analyze fur seal milk and scat samples collected at a U.S. field camp in the South Shetland Islands. I went to sea for six weeks during the Antarctic summer and did lipid analyses on milk samples and sorted poop, but I also got to help in the lab with identifying zooplankton samples. When our ship surveys switched to winter, I still wanted to go to sea, but I didn’t have samples to work on—the field camps close in winter—so I proposed that I do lipid and stable isotope analyses on Antarctic krill and other zooplankton species. I went to sea for five winters in a row and studied what krill and other zooplankton eat during winter, which wasn’t well studied before.
Q: What research are you directly involved in?
Unfortunately, we stopped doing ship-based oceanographic surveys in 2016 because it was too expensive to go to sea each year. Instead, we began using autonomous underwater gliders in Antarctica for our krill research. I went from doing biochemistry almost exclusively to being a glider technician and pilot, which had a steep learning curve! But I got to trade in my lab coat for a hard hat, which is kind of fun.
Q: Gliders? Tell us more.
Gliders resemble large, yellow torpedoes, and they carry sensors on them that collect almost all of the same data we used to collect from a ship, including krill biomass data and measurements of water properties, such as temperature, salinity, dissolved oxygen, and chlorophyll concentration. They can even take underwater pictures of zooplankton. Each glider is powered by three big lithium batteries, and they can remain deployed for more than three months and cover hundreds of miles while diving to more than 3,000 feet below the ocean surface. When they surface between dives, we can talk to them over an Iridium satellite connection from anywhere in the world using a laptop and an internet connection, so we don’t even need to be in Antarctica to control them. Working with gliders has been a big change for our program but also an exciting one as more and more research programs—including several in Antarctica—have started using gliders for ecosystem studies.
Q: Do you control gliders from San Diego? Or are they preprogrammed and hopefully stick to the plan?
Yes and yes! We deploy the gliders with a waypoint plan, which is a path of GPS coordinates. We try to replicate the same path each year to make our annual biomass estimates comparable. However, the ocean doesn’t always cooperate, so we don’t always exactly stick to the plan. For example, every year we monitor iceberg positions as well as areas of high ice concentration, and we may need to alter the waypoint plan to steer the gliders around ice. In other years, currents may be extreme, and our gliders are so big and slow that they can’t fight currents that travel faster than them, especially if they’re in shallow water. Sometimes we need to steer gliders out into deeper water, away from coastal currents, and then get them back on their original paths. But when they’re in deep water and light currents, and sea ice cover is low, they are fairly autonomous. Throughout our glider deployments, which run 60 to 100 days, we have a glider pilot on duty 24/7. I frequently pilot gliders in my pajamas from my living room couch!
Q: What’s the ultimate goal of NOAA’s Antarctic krill research?
Under the U.S. Antarctic Marine Living Resources Convention Act of 1984, the AMLR program has a legislative mandate to conduct ecosystem research in Antarctica with the goal of managing Southern Ocean living marine resources. To that end, our main objective each year is to estimate the biomass of Antarctic krill in a specific area around the northern Antarctic Peninsula where seals and penguins feed during the summer breeding season. Based on our data, we provide management advice to the Commission for the Conservation of Antarctic Marine Living Resources, which is the international body that sets catch limits for the growing krill fishery.
Q: What’s something you’d like everyone to know about Antarctica?
Well, winter might sound harsh, but you’re less likely to get seasick because there’s no ocean swell due to the thick sea ice. People often ask about changes in the environment, especially in sea ice, over the years I was there. Variability in sea ice cover is normal, but I think the changes in sea ice cover since we started using gliders have been more alarming. We first flew gliders in Antarctica in 2018, and we were constantly navigating them around icebergs and patches of sea ice. Since then, we’ve barely had to navigate around sea ice at all, and it seems that this upcoming field season, which starts in December, will be worse, as 2023 is on track to have the lowest amount of sea ice in Antarctica in more than 40 years. This loss of sea ice is devastating for the ecosystem in Antarctica, because so many animals—from the tiniest zooplankton to seabirds to some of the biggest marine mammals—depend on sea ice to survive, especially during winter. But melting sea ice isn’t just devastating for Antarctica—it can have negative consequences for the entire planet. I want people to know that even though Antarctica is far away from where most people live, we should all be concerned about the alarming loss of sea ice in Antarctica and how that may affect the climate all over the world.
Q: What inspired you to create an Instagram comic strip?
I love science communication, telling stories about science. I write a blog for NOAA Fisheries called “Glider Piloting With Jen: All Systems Go!” about how we use gliders for our research. But I also wanted to do something that focused on raising awareness about krill and how their habitat has been affected by climate change. I love to doodle, so I got the idea to draw a weekly comic for Instagram. For a few months, my mom and a few friends were my only followers, but now I have a decent following of fellow Antarctic science nerds. I try to make each comic educational in some way, but sometimes they’re just silly. I hope people see them, are curious to learn more about krill and the important role they play in the Antarctic ecosystem, and are inspired to live in a way that reduces the human impact on all environments—especially vulnerable environments like Antarctica.
Q: What does the future hold for krill research in Antarctica?
I’m not sure, but I think we have to focus on how krill populations will respond to future warming and less sea ice. The health of the Antarctic ecosystem hinges on how much krill is available in the future.