Kevin Arrigo studies some of the teeny tiniest organisms on the planet -- microscopic plants called Phytoplankton that scientists think might produce up to 50 percent of the Earth’s oxygen. To get at what makes these itty bitties tick he climbs aboard giant ice-breaking ships and heads out to the planet’s icy North and South where they are the most active. Arrigo chatted with us about what it’s like to work in the world’s polar regions and what it feels like to take a wrong step and get a boot full of freezing arctic water.
Do you consider yourself a biologist?
I’m a biological oceanographer. I study the biology of the ocean at a pretty large scale. I’m not a marine biologist. I look at really big ocean issues. One example is the organisms that are the base of the food chain, microscopic phytoplankton. They’re tiny plants that feed everything in the ocean and produce more than 50% of the oxygen we breathe. Most people think of trees, but it’s mostly the phytoplankton that are doing the work.
They’re responsible for the coming and going of the ice ages, which is driven by changes in atmospheric CO2. When the winds pick up, the ocean gets fertilized by iron-rich dust blowing into it. This stimulates phytoplankton to suck CO2 out of the atmosphere and then the planet starts to cool. After thousands of years, the temperatures drop so far that the planet goes into an ice age.
The place I study phytoplankton is in the polar regions. They’re places we don’t understand very well. The North Pole and the area around Antarctica are very different. Most of the climate change is driven by phytoplankton in and around Antarctica. The ones growing in the tropics have very little impact on Earth’s climate.
Around Antarctica, the ocean is a big watery place full of microscopic plants and they need nutrients just like your garden – mostly nitrogen or phosphorus. Luckily the Antarctic has lots of nitrogen and phosphorus, but not much iron. The ocean can become anemic too. Warm times like now, the ocean is really anemic - not much iron is being blown into it.
Does that mean we could theoretically combat climate change by adding iron?
There’s been at least 13 large scale experiments where people have dumped iron into the ocean to see if you can stimulate phytoplankton to grow. It works, in a sense. We can fertilize the phytoplankton and make them grow quickly and take up lots of carbon dioxide. But in many cases the experiments have been done in weird times or unusual places so the results have been mixed. The key thing is that you have to sink the phytoplankton away from the surface ocean, because when the plankton dies, they’ll decay and the carbon is just released back into the atmosphere.
How would you get them to sink?
I was funded by the Department of Energy for a while and we were doing models of this. What would happen if you took a virtual ship and dumped virtual iron into the ocean, what kind of impact could you expect? It’s a really expensive experiment to conduct.
It’s one of the geoengineering solutions for climate change. You can pull CO2 out of the atmosphere, this solution doesn’t require a point source of carbon, but you have to spread a lot of iron over a very wide area. And we don’t know if it has an impact on the biology -- food webs and all that stuff.
This would be tinkering on a really large scale. There are actually companies trying to do it to get carbon credits.
What are you working on right now?
We study both poles. The Arctic is losing all it’s summer ice. For me I jumped into that field because I’d been doing Antarctic research for most of my career. I thought all the sea ice is going away and there’s all this new habitat for phytoplankton to grow. Ice blocks light and they can’t grow. And 2007 was the year where there was 23% percent less ice than we’d ever seen before in the summer.
What do the phytoplankton do now that there’s less ice?
We started first studying them with satellites because it’s cheaper. What we found is that as the ice is going away the Arctic Ocean is becoming more productive. This is almost certainly going to drive ecological changes that we don’t understand yet -- it’s just too soon.
So we got a cruise together to look at what’s happening off the coast of Alaska, in the Chukchi Sea. It’s a really neat place. A pretty shallow ocean, only 40 meters deep and really biologically productive. There’s just whales and walruses and seals all over the place.
That’s where we made this big discovery in 2011. The paradigm had always been: the ice starts to go away and the phytoplankton starts to grow. The blooms don’t begin until the ice melts in June or July. But in 2011, under 3 feet of ice, there was this enormous bloom of phytoplankton. It was way under the ice. It was the highest concentration of phytoplankton ever measured anywhere in the world. The water was pea soup green. We were drilling holes to sample the water and you couldn’t see the bottom of the hole. It was like that for 200 feet under the surface ocean. We couldn't believe it! Anytime we’ve ever sampled under the ice you find by the time you get into the ice there’s nothing.
So we went back and studied that again this summer. And unfortunately this time we went too early and it was just primed and ready to go. The reason phytoplankton can grow under the ice is that when the snow begins to melt, it forms ponds on the surface that let in lots of light. The Arctic used to be really thick old ridged ice. But now it’s really new flat ice because it melts and re-freezes every year. Years ago, it used to be this rubbly mess you couldn’t get an icebreaker through. Now these nice ponds form on the surface and they act like windows and let all the light through the ice. But in 2014 it never got warm enough for the snow to melt all the way. It came so close, it would tantalize us for a couple days and then it would snow again
Did you manage to learn anything on that trip?
We found a lot of things we wanted to know in terms of the physical and chemical system that makes these big phytoplankton blooms grow. We knew that lots of light isn’t enough. You need lots of nutrients too. In the past, whenever scientists would sample the water, they’d find little or no nutrients at the surface. We thought maybe they were there in the winter and by the time scientists got there in the spring the phytoplankton had consumed them. When we sampled this time in early spring, there were lots of nutrients everywhere. We knew that as soon as the lights come on they’ll be ready to go.
Do you do the same type of research in the South Pole?
In the Antarctic the questions are different. We deal more with: What controls the kinds of phytoplankton that grow there? There’s two main groups in the Antarctic. One consumes twice as much CO2 then the other one does so it’s really important to understand what factors allow one to grow better than the other. We’re doing a lot of physiological work on the phytoplankton -- measuring growth rates, photosynthesis (fixing carbon), and other stuff to see how healthy they are under different conditions of light and nutrients.
What we’re doing in the cruise coming up in October is to look at the molecular biology of the phytoplankton, their genetics. If you add iron what are the genes turning on? What are they doing to acclimate to not having enough iron? How do they use it when it becomes available? One kind might be better at taking it up than the other. What dictates the winner of the competition between the two groups?
What are the two groups?
One is diatoms, they have little glass shells and they’re the most productive phytoplankton in the world -- 25 percent of oxygen on Earth is made by them. The other one is called Phaeocystis -- little round balls that are brown. They’re the ones that take up lots of carbon, lots more than diatoms.
Some people think that changes in the amounts of these two kinds of phytoplankton has an impact on CO2 in the ocean – and may play a role in the wax and wane of ice ages. There’s a big drop in CO2 before an ice age and part of the explanation could be that the ocean switches from a dominance of diatoms to Phaeocystis. That’s why it’s important to understand what makes them both of them tick. We want to understand their genetic adaptations.
That’s what were going to do October 26 - November 26.
Are you headed down there on a US research ship?
Yep, it’s the National Science Foundation leased Nathaniel B Palmer. Sometimes you have to share the ship. This time we’re taking 20 people on our team. The Stanford group is 14 people and 6 from our collaborators from Woods Hole.
What’s your job on the ship?
I’ll be the chief scientist when I go which means that I’m in charge of the research. There’s a captain who runs the crew and I run the science team. So it’s up to me if there are decisions to be made about where we’re going to sample and what we’re going to do.
There’s a lot of planning involved. We try as much as we can to predetermine where we’re going to do sampling. We do a lot of water sampling. There’s an instrument called a CTD that measures conductivity temperature and depth that we drop in the water and send it all the way to the bottom. It gives us a vertical picture of temperature and salinity. We also wrap a bunch of bottles around it on a carousel so that we can stop the instrument at any depth and close a bottle to traps a parcel of water inside. Then we just bring it to the surface. So you can measure the concentration of nutrients, phytoplankton, chemistry, and biology anywhere in the water.
When we’re doing a station we always do that. The Rosette is the name of the carousel that the bottles are hooked to, and we also attach a fluorometer which measures fluorescence of chlorophyll. If we’re studying 200 meters of water, we may only collect water from 6 depths, but the fluorometer can help us estimate how much phytoplankton there are at every depth, especially when we use it with a transmissometer, which measures particle concentrations.
Particles of what?
Particles of anything. The transmissometer measures light scattering. If a beam of light hits a particle it’s going to scatter. So if you’re near the coast and there’s sediment or if there’s living particles, it will scatter the light. If you want to know what the particles are, you can put a video camera on the Rosette and take pictures of all the particles as you go down.
What’s a “station”?
What you're doing is taking a ship and moving around and every once and a while you stop. Oftentimes you design a grid and every 10 km you stop and sample the water. By the time you’re done you want to map properties of the area you care about. So you need to figure out where you're going to stop and make the measurements. So we’re going along and we may stop every 10 km and do a station. It’s a place you’re making measurements.
There are some things you can measure continuously. The ship has water intake and you can make nice maps because the ship always knows where it is.
We also get off the ship onto the ice if it’s around. And if you do that in the Antarctic the penguins come from all around to see what you're up to.
But the station work is the bulk. You can do it on the ship or in a small boat. It’s easier to do it off the ship. If we’re doing optics it’s hard to do it from the ship because it casts a big shadow. We like to get away from the ship a bit.
We also get off the ship onto the ice if it’s around. You park the ship, lower the brow -- basically a gangplank -- over the side and walk down onto the ice. And if you do that in the Antarctic the penguins come from all around to see what you're up to.
In the Arctic you have to worry about polar bears and you have a guy on the ship with a gun spotting. I’d be really nervous knowing there were bears out there.
So we’ll also sample the ice and it’s similar things we measure there. Phytoplankton that live in the water and algae that live in the ice. We look at those too. One of my students is interested in the relationship between what’s growing in the ice and what’s growing in the water. Does that seed the bloom in the water column?
What do you wear on the ice?
We do use special gear but we probably don’t have to. It’s a few feet thick. Everybody is geared up with boots and foul weather gear. But at least one time during every cruise we have ice liberty. Where it’s just a fun day on the ice. So people are down there in bathing suits and shorts. We have frisbee games and just hang out like a day at the beach.
Isn’t it cold?
We try to pick a nice day. It’ll be around freezing, but if it’s sunny and you’re running around you get hot. You end up in shirt sleeves pretty quickly and you really do acclimate. What seems cold at first after a week isn’t that cold anymore. But you don’t wanna end up in the water.
When we’re working we wear the standard issue gear. Better safe than sorry. But it’s probably more then you need.
How long is the climb down from the deck to the ice?
It’s maybe 20 feet vertically. The gangway is 40-50 feet long on the Healy. On the Palmer they lower us down in a basket from a crane. It’s real quick. It’s not scary, unless you're afraid of heights. You’re in this netting. It’s a rubber inner tube with a tarp on top of it and it’s totally encased in mesh and connected to a crane so you can put lots of equipment in it. You couldn’t fall out of it if you wanted to.
The gangway, depending on how steep it is, is a little dicey. Especially if you’re carrying stuff. It’s steep and walking without holding onto the rails is tenuous. Climbing down the gangway takes like 15 seconds but it’s a brisk walk.
It’s slower going up. Your boots tend to slip off your feet when you're going up.
What’s it like on walking around on the ice?
The ice is nothing like lake ice, which is really hard. This stuff is pretty soft because it’s made out of ocean water the salt stops it from freezing solid. It’s always a little more porous and it’s kind of crunchy. There’s not a lot of snow because there’s not much precipitation at the poles. You don’t get ice with two feet of snow unless there’s a ridge and the snow drift has blown up on it. The thickest snow we see in the Arctic is 15 or 20 cm. We drill through the ice to collect our samples and we never had to shovel snow away.
Have you ever fallen through the ice?
Depending on when you’re there it might be covered in melt ponds that are about a foot deep. Later in the season they connect to the ocean and you can fall through. In the Arctic the Coast Guard, which runs the ship, doesn’t let you into melt ponds unless you have a dry suit on. Even then you’re roped up and there’s somebody on the edge of a pond holding a rope around your waist.
I have fallen through ice before. I stepped in walking on the ice in Antarctica. There was a crack in the ice that was covered in snow and my foot went all the way through into the water and I got a boot full of water.
How do you take ice samples? Do you drill?
We’re actually taking cores so we have to have a hollow-barrel drill. We’ve been using an electric drill on top, which makes the core barrel spin. You take little augers and drill holes. It’s not like ice fishing, it takes forever when you’re ice fishing on a lake because the ice is so hard. But this ice is like cutting butter. So one core barrel is 3-feet long. If the ice is deeper you pull the core barrel out, put an extension on, and put it back in and get the rest of the ice. You can also use a hand-auger drill and make a hole if you just want to measure how thick it is. We take ice physicists with us and they concentrate on all that stuff.
How did you get into this type of research?
When I went to grad school I would always say: “I’m never going to anyplace that’s cold or study anything that I can’t see with my naked eye.”
I was interested in ecology and ecosystems and I wanted to do mathematical models of them. But I didn’t know what I wanted to do with that.
The first thing I did was actually to study Balinese rice agriculture. I went to Bali and they were trying to understand how to maximize rice yield. It was a really neat system to model, but I was going to have to become an anthropologist if I wanted to pursue that.
I was at USC and one of the professors was going to the Antarctic for a two-year field season at McMurdo station. He said I could come if I wanted to do models there.
When you model there’s always something you don’t know without making measurements in the field. And I realized I didn’t know anything about how phytoplankton responds to salt or light, so I went down there and made the measurements. But you go down there for the first time and you’re hooked. Its just so cool.
Photos courtesy Kevin Arrigo
Not all science is done in a lab by guys in white coats staring into microscopes. Lots of discoveries require brave men and women to put their boots on the ground and get down and dirty in dangerous environments. Every month we’ll profile one of these field scientists, tell you how they do their job, and explain the science behind what they do. If there’s a scientist or field of science you’re dying to hear more about shoot us an email or a tweet: erin at erinbiba dot com, @erinbiba