Lake Joyce!
(Written Oct 23)
I’ve been at Lake Joyce for a week now. We’ve set up all our tents and melted a dive hole. The science gear is unpacked and being used on the first samples! All had gone very smoothly, and we are way ahead of schedule. And the mats are recovering and precipitating calcite! Here’s an abbreviated description of week 1:
Steve and I arrived into camp last on Saturday, and the weather was beautiful - bright sun and no wind. It was warm! Megan (from the BFC) had already set up my tent, so I just had to move in. The cook tent, the toilet tent, and the land-based science tent were also already up. Everything looked great. Over the next two days, Megan and Leah (BFC) assembled the floors for the tents we put on it ice, one for dive gear and one for science. They put up the tents with a bit of help from us. The rest of us sorted gear out and got things organized. Evenings were lots of fun with Megan and Leah and always included lots of laughter. They flew back to McMurdo on Tuesday. The weather was beautiful the whole time.
On Sunday, we started melting the dive hole. To do so, we pump heated antifreeze through a coil that is placed on the ice. We pump the melted water out of the hole. We ran the system 24 hour per day for about 2 days before the lake water started seeping into the hole. Once it started, the hole filled in 10 minutes, so there wasn’t any time to climb down into it this year. The ice is much thinner for this hole - only slightly more than 4 meters versus the slightly more than 5 meters we had last year. That meant we didn’t stop soon enough to be able to sample the ice, etc. Once the hole is filled, with water, it can take a long time to melt through the last bit of ice because all the heat tends to go up into the water rather than down into the ice. The hole was through by the end of Tuesday; it was very nice to have the dive hole ready so quickly.
We didn’t have all the necessary gear for diving on Wednesday, so we spent that day getting organized and working on miscellaneous things. Tyler and I got his underwater stereo video cameras going and lowered them into the dive hole. Here are some cool images:
<network connection too slow>
Thursday was our fist dive day. Ian went in first to put caps on the sediment traps that we left in the lake last year. That has to be the first thing to do so that the divers don’t actually disturb them and add more sediment. We need to know how much sediment falls out of suspension in the lake water to understand how much the mats get buried and how they respond to sediment. He brought up three of the six bottles, and Dale brought up the other three on his dive. He also looked around and saw that the deep water microbialites that we sampled a lot last year have active growth on their tops, which is a big improvement over last year. On Friday, Dale collected two samples in core tubes. One got a bit disrupted, but the second sample came up beautifully. Ian took down the diving PAM fluorimeter, which measures the activity of photosynthesis on the mats. He found that the mats at about 13 meters depth are much more photosynthetically active than they were last year. The signal was much weaker on the tops of the deep water microbialites. Ian collected some pinnacle mats from 13 m water depth.
It was great to have samples. The 13 m pinnacles are very photosynthetically active, so we imaged them using the imaging PAM fluorometer, which give the distribution of photosynthetic activity on the structures. We also looked at the various bacteria under the microscopes. We found two different sizes of leptolyngbia, one probably phormidium species, and one pseudanabaena. There are also several types of diatoms, but they aren’t very abundant in this sample. All of these organisms are photosynthetic and they have lots of pigments showing that they are active. The proportions of the different species varies with position on the pinnacles, which shows that they are taking advantage of different ecological niches.
In addition to having interesting species distributions, the pinnacles show lots of evidence for calcium carbonate mineral precipitation associated with the microbial mats. There are tiny flecks of CaCO3 almost everywhere and there are a few larger crystals with good crystal faces. I am quite sure that we’ll find that the photosynthetic activity of the mats is influencing the isotopic composition of the CaCO3. This will be a very exciting result.
The deeper cores that Dale collected also have varying microbial communities on different parts. We looked at the one that got disrupted during sampling. It contains lots of diatoms on the top, as well as abundant leptolyngbia of the slightly larger size. I also looked at two pinkish stripes that ran up the side of the structure. They also contain abundant leptolyngbia and diatoms, but the diatom species vary as do the filament diameter. I think that the communities vary even on similar-looking structures on the microbialites. However, because there are many fewer living cells in general, this variation might be due to chance colonization effects rather than stable ecological differences. I think that we’ll need to look at several samples to see which is the case. If they all have the same species at the peaks, that distribution probably represents a stable ecological difference, whereas if they are all different, it’s more likely to be a chance colonization effect.
Today (Saturday) was a less successful dive day. Dale decided he is too congested to dive. Ian started a dive, but had too much trouble clearing his ears. Thus, he came back up. This afternoon, Tyler did his first dive. He was over weighted and had trouble with buoyancy. That, combined with too much water in his mask made his dive short as well. At least we have several good samples to work on and the mats are growing well. We’ll have lots of time to work on them over the next several weeks!
I’ve been at Lake Joyce for a week now. We’ve set up all our tents and melted a dive hole. The science gear is unpacked and being used on the first samples! All had gone very smoothly, and we are way ahead of schedule. And the mats are recovering and precipitating calcite! Here’s an abbreviated description of week 1:
Steve and I arrived into camp last on Saturday, and the weather was beautiful - bright sun and no wind. It was warm! Megan (from the BFC) had already set up my tent, so I just had to move in. The cook tent, the toilet tent, and the land-based science tent were also already up. Everything looked great. Over the next two days, Megan and Leah (BFC) assembled the floors for the tents we put on it ice, one for dive gear and one for science. They put up the tents with a bit of help from us. The rest of us sorted gear out and got things organized. Evenings were lots of fun with Megan and Leah and always included lots of laughter. They flew back to McMurdo on Tuesday. The weather was beautiful the whole time.
On Sunday, we started melting the dive hole. To do so, we pump heated antifreeze through a coil that is placed on the ice. We pump the melted water out of the hole. We ran the system 24 hour per day for about 2 days before the lake water started seeping into the hole. Once it started, the hole filled in 10 minutes, so there wasn’t any time to climb down into it this year. The ice is much thinner for this hole - only slightly more than 4 meters versus the slightly more than 5 meters we had last year. That meant we didn’t stop soon enough to be able to sample the ice, etc. Once the hole is filled, with water, it can take a long time to melt through the last bit of ice because all the heat tends to go up into the water rather than down into the ice. The hole was through by the end of Tuesday; it was very nice to have the dive hole ready so quickly.
We didn’t have all the necessary gear for diving on Wednesday, so we spent that day getting organized and working on miscellaneous things. Tyler and I got his underwater stereo video cameras going and lowered them into the dive hole. Here are some cool images:
<network connection too slow>
Thursday was our fist dive day. Ian went in first to put caps on the sediment traps that we left in the lake last year. That has to be the first thing to do so that the divers don’t actually disturb them and add more sediment. We need to know how much sediment falls out of suspension in the lake water to understand how much the mats get buried and how they respond to sediment. He brought up three of the six bottles, and Dale brought up the other three on his dive. He also looked around and saw that the deep water microbialites that we sampled a lot last year have active growth on their tops, which is a big improvement over last year. On Friday, Dale collected two samples in core tubes. One got a bit disrupted, but the second sample came up beautifully. Ian took down the diving PAM fluorimeter, which measures the activity of photosynthesis on the mats. He found that the mats at about 13 meters depth are much more photosynthetically active than they were last year. The signal was much weaker on the tops of the deep water microbialites. Ian collected some pinnacle mats from 13 m water depth.
It was great to have samples. The 13 m pinnacles are very photosynthetically active, so we imaged them using the imaging PAM fluorometer, which give the distribution of photosynthetic activity on the structures. We also looked at the various bacteria under the microscopes. We found two different sizes of leptolyngbia, one probably phormidium species, and one pseudanabaena. There are also several types of diatoms, but they aren’t very abundant in this sample. All of these organisms are photosynthetic and they have lots of pigments showing that they are active. The proportions of the different species varies with position on the pinnacles, which shows that they are taking advantage of different ecological niches.
In addition to having interesting species distributions, the pinnacles show lots of evidence for calcium carbonate mineral precipitation associated with the microbial mats. There are tiny flecks of CaCO3 almost everywhere and there are a few larger crystals with good crystal faces. I am quite sure that we’ll find that the photosynthetic activity of the mats is influencing the isotopic composition of the CaCO3. This will be a very exciting result.
The deeper cores that Dale collected also have varying microbial communities on different parts. We looked at the one that got disrupted during sampling. It contains lots of diatoms on the top, as well as abundant leptolyngbia of the slightly larger size. I also looked at two pinkish stripes that ran up the side of the structure. They also contain abundant leptolyngbia and diatoms, but the diatom species vary as do the filament diameter. I think that the communities vary even on similar-looking structures on the microbialites. However, because there are many fewer living cells in general, this variation might be due to chance colonization effects rather than stable ecological differences. I think that we’ll need to look at several samples to see which is the case. If they all have the same species at the peaks, that distribution probably represents a stable ecological difference, whereas if they are all different, it’s more likely to be a chance colonization effect.
Today (Saturday) was a less successful dive day. Dale decided he is too congested to dive. Ian started a dive, but had too much trouble clearing his ears. Thus, he came back up. This afternoon, Tyler did his first dive. He was over weighted and had trouble with buoyancy. That, combined with too much water in his mask made his dive short as well. At least we have several good samples to work on and the mats are growing well. We’ll have lots of time to work on them over the next several weeks!
