Mail Buoy: December 1, 2011

Hi Mary,

This is a good question, and there are several answers. Hypersaline basins are not uncommon and are becoming more widespread in certain parts of the world, and it is unknown the extent to which the microbes in them contribute to nutrient cycling. Their communities might represent a significant biomass that affects marine biogeochemcial cycles.

Additionally, the organisms that live in these basins most likely have unique genes and proteins that help them to adapt to the conditions here. Therefore we are here to learn more about the genes and proteins that they express so we can understand how marine organisms can adapt to such extreme conditions.

These basins are also great study sites for learning about how changes in water chemistry affect microbial diversity and activities since the chemistry of each DHAB is unique. From the standpoint of evolution, these basins have been separated from one another for thousands of years, and they are therefore interesting sites to study how microbial communities may evolve to become distinct from one another
based on local physiochemical conditions.

Finally, the conditions in some of these DHABs are possible analogs for certain extraterrestrial habitats.

Thanks for following our expedition, Mary, and keep on checking in with us!

Dr. Ginny Edgcomb

Hello Saffana,

The deep-sea brine lakes we are sampling on our expedition are still relatively new to science. The organisms that are capable of living in these harsh environments are therefore still largely unknown. Therefore, we all hope that we will discover many novel organisms. When we then describe these organisms based on their looks, their ecology, their genes, and their metabolism, we will be able to place these novel organisms into the big Tree of Life. This Tree of Life aims to reconstruct the relationships between all living creatures on our planet, from the smallest microbes to the largest whales.

Furthermore, the Tree of Life will help to reconstruct the evolutionary (ancestral) history of life. Each new species that is added to the Tree of Life helps to get one step closer to these goals.

Yours truly,
Dr. Thorsten Stoeck

Hi Lachlan! You're the first of my students from Falmouth Academy to write to me! We eat very well on the ship. Atlantis has wonderful cooks who make us all sorts of things. Tonight was roast beef, scalloped potatoes, broccoli, rice, shrimp scampi, homemade cake, and whatever we wanted to drink. Pretty good options, right?

The rescue put our experiments on delay by one day. We cut out a few experiments, as a result. We are using the remotely operated vehicle Jason as well as the SID-ISMS, which you can read about on this Dive & Discover website. There are a few little glitches with the SID that we are working out, but other than that, things are going pretty well! I miss you guys! Say hi to Ms. Gunnard for me!

Dr. E

Hello Jocelyn,
You and your classmates’ questions are very good. It looks like you all may make very good scientists one day.

First, let me get to the eyes of deep-sea creatures. Most creatures that live below 1,000 meters water depth have either no eyes at all or non-functional eyes. Simply because, as you already noted yourself, they don't need eyes down there in the pitch-black darkness. But you will also find some that actually do have eyes, even though they are useless. And again, you are absolutely correct by assuming that evolution should have kicked in and changed these species. However, evolution takes some time. Sometimes even hundreds of thousands to millions of years. And maybe, the eyed deep-sea organisms have discovered the deep-sea as a habitat only relatively recently and evolution has not yet progressed far enough to eliminate the useless eyes.

But to a depth of 1,000 meters, you can find many different organisms with eyes. Their eyes are very special. They still can detect the tiny bit of light that travels through the water and is invisible to the eyes of most organisms. But also, light is produced by many deep-sea creatures (biolouminescence), as a means of communication, for example. In this case, the eyes are needed to record these bioluminescent signals.

Our dive robot, Jason, most likely produces some heat. But to be honest, I do not know if anyone has ever measured the exact temperature. But if high enough, I could very well imagine, that that a temperature-sensitive organism like the shrimp Ms. Shield told you about could detect our vehicle.

Deep-sea creatures have many different modes of detecting their food. They can hear and also smell and taste. Also movements of the prey can be detected because the muscle contractions that are necessary for movements create electrical signals that can be detected by the predator.

Thank you for writing,
Dr. Thorsten Stoeck

Hello Natalie,
These are two highly interesting subjects. It was more than three billion years ago when the first life forms appeared on Earth. At this time, Earth was a very hostile environment, not comparable to the conditions we can enjoy today. For example, temperatures were still very high in many places, Earth’s early atmosphere was free of oxygen but included a number of other gases instead, some of which are highly toxic to most of today’s life forms. One such substance is hydrogen sulfide (this is the gas that smells quite like rotten eggs). Beneath the ocean surface, we still can find environments with such conditions, as for example in hydrothermal deep-sea vents. Also the deep hypersaline lakes that we are studying during our expedition lack oxygen and have high concentrations of hydrogen sulfide. Thus, they share some characteristics with the conditions on early Earth.

How do we know that the conditions in "our" brine lakes in the deep blue are similar to conditions on other planets? There is one decisive characteristic that the brine lakes share with other planets. This characteristic is one of the main reasons that prevented the evolution of life on the planets that we have studied so far. Namely, the lack of water. Each living organism needs water in order to keep its basic cellular processes going. As a smart student you now most certainly wonder, why do we lack water in the deep-sea brine lakes? The answer to this question is that the high salt concentration binds all available water and even attracts the water that is within living cells (this process is called "osmosis"). Therefore, the amount of water that is freely available to organisms in the brine lakes is close to zero (scientists speak of a "low water activity"). And this water activity in the brine lakes is as low as on other planets such as Mars. Studying the organisms living in the brine lakes and their adaptations to a low-water activity environment may give us some clues about the possibility of life forms on other planets without obvious sources of water.

Yours truly,
Dr. Thorsten Stoeck

Thank you for your questions. We do not fully understand your first question.  If you could be more specific we would be happy to try to answer it. Your second question is interesting. We really don't know the exact conditions on other planets or the moons of other planets because they have never been directly sampled.  But, the data that exists suggest that the brine pools we are looking at may resemble a habitat that could potentially exist on another planet.  For instance, one of Jupiter's moons called Europa has been speculated to have a similar chemistry to some of the brines we are studying. DHABs are one of the closest natural habitats on Earth that microbiologists have as a proxy for an extraterrestrial habitat.

Dr. Bill Orsi and Colin Morrison

Hi Caroline,
There are many unique symbioses between hosts and prokaryotes (bacteria and archaea).  But, whenever we look for new symbioses, we typically find them!  As for how they survive with so much salt, that is one of our research questions and we hope to find out.  Thanks for your interesting questions!

Dr. Joan Bernhard

Hello Caroline,
These are excellent questions. Such questions are actually the motor of scientific research. We know a little bit about the importance of symbiosis in such harsh environments. And indeed, symbiosis with bacteria is a very successful strategy of numerous protists to conquer such extreme habitats.

In a mutualistic symbiosis, one of the partners helps the other to cope with conditions that may be very harmful or even lethal. For example, some bacteria can detoxify gases such as hydrogen sulfide, which we find in high concentrations in the brine lakes. In return, the organism that detoxifies the gas obtains nutrients that are produced exclusively by its host.

How protists survive in such high salt concentrations is one of our major aims to find out. Higher organisms such as plants and animals can have a mechanism to actively excrete salt from their interior. This way, they keep their interior salt concentration quite stable. Other mechanisms include the production of substances that are called "osmolytes." These substances are not salts, but create an environment within the cell that mimics the exterior high salt concentration. This way, the cell does not lose water to the exterior. You may have learned in class about the process called osmolysis, in which water is always attracted to the higher salt concentration.

Yours truly,
Dr. Thorsten Stoeck

Hello Maxime,
Thank you for these interesting questions! Basically, we have several approaches to track down any life forms in the deep brine lakes. One tool is cultivation. We simply take some water from the environment, put it in a container, add different nutrients, and let it sit for a while in our laboratories. Then, after a while, we take some samples from these cultures and screen these samples under a microscope, which is very similar to what you probably work with in your science class. If we are lucky (and we need a lot of luck), we can find some organisms that like to grow in our nutrient-enriched samples.

A more complex strategy to find life forms is to look at organisms’ genes, which we extract from water samples that  take in the brine lakes. Each organism has a very specific set of genes, and we use these genes to identify if and what organisms live in the brine.

To study how these organisms live without oxygen, we need to culture them. It requires many thousand cells to do experiments and gene analysis. We can detect specific genes that are responsible for the respiration process. Depending on which genes we can detect in such a culture, we can conclude their mode of respiration. The principal organelles that produce energy under oxygen depletion are already known to science and well described.

Yours truly,
Dr. Thorsten Stoeck

Dr. Joan Bernhard adds a P.S.
Hello Maxime,
If you follow along throughout our cruise, you will learn about some of the methods we use to show that organisms are living in these habitats. We already know of many protists that can live without oxygen, so we are not starting without some background knowledge.

Dear Sarah,

Well, your question made me smile. I guess since we have worked so hard on the new instrument that we brought, I was very hopeful (more sure) that it would work. But we only received it and fully assembled it one week before we had to ship it to Greece, so we did not have a chance to test it fully in Woods Hole beforehand. So although I expected we would encounter a few problems, I was pretty nervous that the problems would be too difficult to fix at sea. It is also pretty nerve-wracking to watch a new instrument go to 3,500 meters depth the first time. So far, we have been able to troubleshoot all the problems we have encountered. Thanks for asking!

If you are a chief scientist on an oceanographic cruise someday, you will find out that it takes a long time to plan an expedition like this one. I've been working on it off and on for the last year.

Thanks for writing!
Dr. Ginny Edgcomb

Dear Hailey,

I assume that your question is referring to the science crew, and not the ship's crew? The science crew was chosen based on specific skills that each person brings to the work. For example, some are geologists, several are microbiologists, some are aquatic chemists, and some are engineers/instrumentation specialists. In addition, there is a whole team specifically qualified to run the ROV Jason. Together, by pooling our skills, we can achieve more than any of us could by ourselves or if we chose people all from the same disciplines.

The ship's crew is selected more or less on the same logic. On this ship are all the people required to navigate, cook, pilot, maintain, repair, and operate the vessel, since we have to be able to deal with almost anything at sea. Thanks for the great question!

Dr. Ginny Edgcomb





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