Author Archive | rfantasia

Hi All,

Sorry it has been a while since our last blog post. We’ve had a super busy and productive season so far. There are a few posts coming your way to show you what we’ve been up to, both in work and free time. So heeeere we go…

Once we got our krill from the Lawrence M. Gould, we decided to kick off the season with some short term experiments. The purpose of these is to see how krill physiology changes over a short time period (48 hours) when they’re exposed to high CO₂ and/or high temperature. Some things that we measured included blood pH, cellular pH, and lactate.

Krill Blood
Krill have an open circulatory system, which means that there are no veins, arteries, or other blood vessels to carry around their juices. Like many other crustaceans, they also do not have any hemoglobin, the iron containing molecule in our blood that carries oxygen and gives it that nice red color. Instead, they use hemocyanin, a copper based molecule, which means the blood is clear-ish and difficult to find in these little guys. Brad and Abigail were able to find a nice large pool of it to take samples from.

Brad drawing blood from one of our krill

Why these measurements?

One way that organisms can keep their machinery running smoothly is by moving things out of cells and into their blood, or vice versa. By measuring the cellular pH and blood pH, we can get an idea of how krill are moving around those little H⁺ ions (acidity).

Lactate works as an indicator of anaerobic respiration, the kind of metabolism that goes on when not enough oxygen can get to muscles in order to produce all of the energy they need. There are a couple of reasons organisms have to switch to this kind of respiration, but either is because they’re using oxygen more quickly, they’re have trouble getting oxygen to the muscles, or some combination of the two.

To measure lactate and cellular pH, their tails were chopped off and frozen to be analyzed back home. We do love our animals, but in order to study them, sometimes we have to do not-so-nice things. We are sorry, and we hope that their sacrifice will benefit the future of all krill-kind. No picture right here, in case it’s something you didn’t want to see, but feel free to click the link below if you do.

WARNING: GRAPHIC KRILL-HEAD CONTENT

Measuring all of these parameters is important, because if a krill’s metabolism is going to change under increasing ocean temperature and acidity, these results can help explain how this change comes about. It will be very interesting to see what we get here – and how it comes together to tell the story of how krill respond to a changing ocean.

Right now Abigail and I are conducting some repeats of this same experiment (which are always good to have in science) as well as a similar experiment where we see how the krill may react to the same conditions over a longer time period (21 days).

Since we ended up with a nice mix of sub-adults (essentially krill in their late “teens”) and juveniles on our first krill delivery, we decided it would be a good time to conduct a juvenile growth experiment. Much like most animals, krill grow more quickly in their early stages than they do once they are nearly full grown – so the juveniles we got are ideal for this kind of an experiment.

We set up three treatments, as usual, each with 30 krill in their own jars. Each jar was observed daily, to see if the krill had molted. Krill do not grow continuously, but they can increase size (or sometimes decrease) each time they molt. Each time a krill molted, we weighed it and measured its length, as well as the length of the exoskeleton it shed. This allowed us to calculate what’s called the growth interval, between the krill and molt lengths.

Measuring krill length

A krill “molt”

Krill typically molt every 30 days or so, and about 25 days later we only have one straggler that hasn’t molted yet. The krill in the high temperature treatment seemed to molt much more quickly than those in the control and high CO2 treatments. This isn’t entirely too surprising, since most biological rates in ectothermic (“cold blooded”) organisms increase as temperature does. It also seems that these guys had a smaller (or negative) growth interval, as compared to the ones in the other treatments. One potential explanation for this is that, under higher temperature conditions, the krill have to devote more energy to metabolism than to growth, but it’s too early to call for sure.

It hasn’t been all work and no play for us at Palmer station this season. Aside from plenty of indoor activities like movies, music, ping-pong, and pool, there is a lot of great outdoors to enjoy down here.

The Great Outdoors

The scenery alone makes sitting around and relaxing a great time. We’ve had plenty of nice sunsets, and watching how quickly the ice can blow in still amazes me. Earlier in the season the sunsets would last for hours, and run right into sunrise with no darkness in between.

And there’s always the glacier, if you want to hike up for an even better view.  The flags mark the edge of a safe hiking area. If you cross them, look out, you’re in danger of falling into a crevasse and spending the rest of the season down there. From up here you can see all of the islands surrounding Palmer station, and beyond. Unfortunately we picked a pretty stormy day for this trek…

We’ve been able to camp out quite a few nights. Some people do almost every day.  There’s not much wood around to start a campfire with, but the weather has been awesome and hardly ever too cold.  No dorm room on station can beat camping out in the backyard – it’s really amazing to wake up in the morning to the grunting call of a leopard seal or the splash of a big piece of ice falling off the glacier.

At first, the 24 hour sunlight was a bit too much, and we would have to pull our hats over our eyes to get some zZzZz’s in the tent, but now it’s getting pretty dark at night and we almost have “normal” sunrises and sunsets.

The Wildlife

Occasionally we’re able to take a boat out to one of the islands near station and do a bit of exploring. We’ve gotten to see some pretty cool wildlife, like these Adélie penguins on Torgerson Island…

…and even some babies, like the fuzzy guy in the pic below.

Even though the penguins get most of the attention, they’re not the only birds around. The brown skuas are my personal favorite. These guys are pretty intense, and have a reputation for dive-bombing scientists that wander too close to their nesting sites. They’ll also snatch up the occasional penguin chick, if given the chance.

We even saw some grass out on Torgerson! It sounds boring, I know, but it was NOT something I expected to see in Antarctica. There is actually a surprising amount of green stuff down here, in small patches. Most the “plant” life is in the water, as phytoplankton or kelp.

You don’t need to get on a boat to see the wildlife around here, though. Just step outside the lab and there’s usually something going on, like lazy seals floating by on ice floes and the other oft-forgotten bird, the noble Showy Sheathbill (probably the animal we see hanging around the most).

Hope this was a nice little break, I know it was for us. Next up….more science!