Our spiny Sterechinus friends
It's time to do some science down here! I've been here for about 10 days now, and I've gotten decently settled into the rhythm of the endless (literally) days. I get up around 6-7am, take a shower and get our gear ready (which can take 30-45 minutes if we're headed out to field sites), then get some breakfast before the line closes at 730. Then it's on to the day! Often times I'm not leaving the lab until 9 or 10pm, so the days tend to be long, and often action packed. Some days are pretty chill however, as evidenced by the fact that i'm currently doing laundry and getting this blog entry in. I'll go over a standard day at some point, but for now I'll give you an overview of the system and what we do out here with Sterechinus neumayeri, an Antarctic sea urchin commonly found in coastal areas all around the continent.
The Question - Ocean Acidification
Every good project needs a good question. Ours is this: In a world of increasing CO2 imput from anthropogenic means, what will happen to animals as the ocean becomes more acidic over the next 100 years.
WARNING: SCIENCE CONTENT FOLLOWING!!!
CO2 is responsible for increasing temperatures worldwide. You already heard that part of the equation. What you might not have heard yet is that CO2 is also (and even less debatably) increasing the acidic content of the ocean. As CO2 equilibrates between air and the ocean surface, more CO2 is added to the bicarbonate buffering process. The equation is pretty simple and looks like this: CO2 + H2O <-> H2CO3 (bicarbonate) <-> HCO3- + H+ (carbonic acid). So, you can see if you put in a bunch of CO2 (with water unlimited in the ocean), the equation is pushed to the right, ending with an increase in carbonic acid. This is dangerous part. As carbonic acid increases in the ocean, the pH drops.
Ocean pH has ranged from 8.0-8.3 over the last 25 million years, with fairly slow (10000-100000 year) changes between these values. Now, while that may not seem like a large shift - remember the pH scale is log based, so each .1 shift is actually 30% more acidic. In the last 50 years or so, the pH of the ocean has dropped .1, meaning a 30% more acidic content of the ocean in 200 -2000x faster than the natural fluctuations of ocean!! And, the scariest part - it's accelerating. Projections put 2100 values somewhere between pH 7.8-8.0 - the lowest recorded in the last 25 million years.
"So what?" - you might rightly ask. Well, the problem is, many animals (including coral, bivalves, crabs, lobsters, and yes our spiny friends the urchins) have calcite shells. These are formed from calcium carbonate (CaCO3). There's some more chemistry involved that i'll skip here (wiki actually has a pretty good overview of the cycle if you're interested), but essentially what happens is, in the presence of CO2, and high acid content, CaCO3 either cannot form, or simply dissolves. So, the shells of these marine inverts either couldn't form or would dissolve away if the ocean became too acidic. "How acidic is too acidic for the animals to survive and grow?" - you might ask next. Well, GOOD QUESTION! That's what we're here figuring out. Using sea urchins as a test animal, and controlled increases in CO2, we're looking at the responses of developing larvae to increased concentrations of CO2 in the seawater - up to very high levels (equivalent to a pH as low as 7.6). Once we raise the larvaes under these varied conditions, we process them for a battery of lab tests - heat shock tolerance, respirometry, proteomics, genomic microarrays, protein content, etc. So, now that you know what we're doing, let's get to the how we do it - with pictures!! -- END SCIENCE CONTENT WARNING
Unlike pokemon, in fact, we do not need to catch them all. But we do need a few hundred for all the projects here. So, how do you think we get them? Well if you watched the intro video you'll know- you should if you haven't yet, i'll wait. It's right down there... in the intro section- no, not the trip down entry, the one...yeah that one - click on the link... yeah i'll wait - it's only like 10 minutes, i'll go check on the laundry...
Laundry's switched to dryer...
Ok, you got it? cool right? We dive for them! Not me personally, although I'd love to get trained up on it. But a couple people associated with our group - who have already taken off actually - grab the urchins by hand during dives. We usually collect a couple hundred of them per dive, at a site called Cape Evans. Field trips will be a different post, as well.
Looks dark down there.... and cold.
Here Steve (red) and Henry (pink - also the guy who made intro video) get ready in their drysuits while the rest of us dive tend.
This is Henry's camera - I loaded this one especially for Dan Schmidt to see. The camera was a gift from Werner Herzog to Henry Kaiser for his work on Encounters at the End of the World. If you haven't seen this awesome documentary yet, you should. It's an artist's eye on a scientist's life down here - I'm doing a lot of what happens in the film, and it still amazes me to watch it.
Once we collect all our Sterechinus friends, we head back to McMurdo and right to the big adult holding tank, where we put all our catch (save those that have spawned on the way over) into the shallow flowing water table.
They love kelp! They munch on it, and carry it around on their backs as both a lunch snack and camouflage.
After the urchins are set and happy, it's time to spawn them. We use KCl to overload their musculature (all the muscles contract) and they release their eggs and sperm. Through a careful testing and mixing process (which unfortunately I was too busy to grab pictures of this time 'round), the fertilized eggs are placed into our experimental buckets. Some are in static culture without added CO2 for bulk material, method proofing, practice work and so on, and most are in treatment buckets with low medium or high (depending on the color tubing you see) levels of CO2.
As they grow through larval urchin development stages (blastula, gastrula, pluteus, etc), we continually check on some of them under a scope to make sure the kids are alright (bonus points if you can get the movie reference in addition to The Who song - if not, google it, i'm being clever here and want full credit).
The larval lab set up
Urchin babies under the scope - so cute. This is 12 hours after fertilization - 4-cell stage, after two cell divisions.
After the urchins reach the stages we're interested in, we freeze a subsection of them for each our downstream processes - of which i'll be most involved in the proteomics and genomic microarray work. And that's it for the sci lessons of the day. Thanks for your attention, there will not be a pop quiz.
Also, bonus picture - the wet lab has a touch tank which all the groups toss in animals that they don't need from collections for everyone to harrass...er...observe gently.
Here's a fun game to play: 5 points per animal identification down to family, 20 points per species name. Oh also all the points are worthless. Go.
Time to check the laundry again....