Audio
The Underground World of Hawaii and the Implications for Life on Other Planets
Transcript
Ranger Dean: Aloha, I’m ranger Dean with Hawai'i Volcanoes National Park and you’re joining us for a podcast. There was a time, not that long ago, when scientists around the world believed that there was no way for life, as we know it, to exist in the deepest parts of the ocean. Crushing pressure and a lack of sunlight would permit only the tiniest of organisms to survive. Then in 1977, researchers studying hydrothermal vents on the floor of the Pacific Ocean uncovered a wonderland ecosystem thriving around the volcanic vents. Later expeditions would reveal mysterious fish, never-before seen crustaceans, and even giant tubeworms. Somehow, in these extreme conditions, life found a way. Today, researchers around the world are surveying some of the harshest environments on the planet searching for “extremophiles” and finding life in the most unlikely of places. One such researcher is my guest today, Dr. Diana Northup, visiting Associate Professor, Biology and Professor Emerita, University of New Mexico. Welcome to Hawaii Volcanoes National Park. I am so glad you could join us for the podcast today:
Diana: It’s a real pleasure to be here and talk with you, Dean, today. I love sharing my passion for lava caves and the mysterious life within them. It mimics, in a way, what you just talked about and it reveals how this featureless environment, where it looks like there’s nothing to eat, is actually a paradise.
Ranger Dean: Yeah, that’s so amazing. I first met you and your husband…uh several years. You were getting permits to survey some of the most remote and beautiful lava caves in Hawai'i. Ah..your husband Kenneth, I should point out is an amazing photographer whose pictures have appeared all over – bringing these strange underground worlds to people who would not otherwise get to visit them. So, what made you want to start searching lava caves for these extremophile organisms?
Diana: Something you may not know, is New Mexico, where I also live, is actually the Volcano State in the west. We can’t compete with Hawai'i but it still has lots of volcanoes, and..um, my husband was getting tired of the drive to Carlsbad Caverns National Park six hours away from our home which is where I did a lot of my research. He said, “Let’s go explore the volcanic caves over at El Malpais National Monument.” Only an hour from our house I might point out. So, that started a decades long passion for lava caves, starting with cave invertebrates which I studied for my master’s degree, and then microorganisms.
Ranger Dean: I’m glad you pointed that out because know that for years, biologists studying cave fauna focused primarily on vertebrate and invertebrate species. What drew you to take a closer look at the microbes?
Diana: So, in 1989, I, just for the fun of it, took a course on Microbial Ecology from Dr. Cliff Dahm at the University of New Mexico. During the course, Cliff handed me these little vials and said, “Why don’t you get some water samples from Lechuguilla where you’re doing your research and let’s see what’s in them.” So, we examined those using scanning electron microscopy, which can magnify things 1000s of times. I saw this tiny organism that was 1/100th of the width of one of my hairs and it looked like a braided rope and there were all kinds of other amazing shapes in water, in a cave, hundreds of feet below the earth’s surface. It was like falling down the rabbit hole in Alice’s Wonderland and I never looked back. I immediately began to shift my research to microbes and pursued a Ph.D. in how microbes eat rock.
Ranger Dean: The first time I saw one of these microbial communities, I actually thought someone had sprayed white paint onto the ceiling of the lava cave, but a second look had me scratching my head in disbelief. These microbial mats were actually millions upon millions of living organisms thriving in complete darkness – but how?
Diana: Actually, billions and billions to quote Carl Sagan. That very question you asked, drew me to this research and my first view of the white microbial mats on the walls that had beads of water all over them really captivated me. I learned that they were called “cave silver” which is actually a very apt title. And I also discovered the amazing world of what we call chemolithotrophy. Big word which basically means the microbes are getting energy and electrons, something you may not think of when you have lunch, from various things in the lava like sulfur, manganese, nitrogen, iron, and many other sources to power their metabolism. So, you might have eaten a hamburger or a tofu burger for lunch – they are actually eating pieces of the rock. Scanning through the literature revealed that very few scientists had studied microbes in lava caves, which left a wonderful gap to fill.
Ranger Dean: Having these microbial colonies thriving in such impossible conditions, it’s like you turned Biology 101 on its head. We opened the podcast talking about this life that was found around hydrothermal vents on the ocean floor where it was discovered that instead of relying on photosynthesis to convert carbon dioxide into organic carbon, the bacteria are actually using chemicals such as hydrogen sulfide to drive their metabolic process. You found something similar when you were doing global sampling in these lava caves. Where did you get your samples from?
Diana: That started with our attending an International Symposium on Vulcanospleology. So, the study of caves in volcanic environments, and it took place in the Azores, islands that are volcanic islands 1600 kilometers from the Portuguese coast out in the middle of nowhere. And I formed a partnership with the Azorean scientists who helped sponsor this meeting and our goal was to explore the microbial communities of the caves on the islands through a grant from the Portuguese government. Other conferences led to research opportunities in Australia, which is really cool. One with really high carbon dioxide that you could only be in for an hour, and also Iceland. And then a cave researcher colleague at the University of Hawai'i -Hilo, Dr. Fred Stone, introduced me to Hawaiian caves, and that was a true love affair with the Hawaiian lava caves. So, we returned in 2008 to do research in Hawaii Volcanoes National Park and other caves on the Big Island. That provided the first more in-depth look at the microbes of Hawaiian lava caves, using genetic sequences just like you might do with your saliva to learn more about genetic background, but also cultures – growing them, geochemistry, what’s in that rock to eat? And scanning electron microscopy – where we could look at them closely.
Ranger Dean: So, let’s talk a little about how you and your fellow researchers went about this. In addition to the microbial mats, you identified secondary mineral deposits such as a weakly crystalline copper-silicate deposit right here in Hawai‘i. It was blue-green in color and it contained reticulated and fuzzy filaments. And we’re going to try to get a photo of this uploaded to the podcast webpage. This is where the story starts to get really interesting. These secondary type deposits weren’t the same as the microbial mats and they weren’t just a rock formation – but the spooky world of something in-between. What are these things, Dr. Northup?
Diana: So they were a real revelation, umm.. but it makes sense if you think about it. So, many microbes facilitate the precipitation of mineral deposits – their specialty. Thanks to my colleagues Dr. Penny Boston and Mr. Mike Spilde, we started looking at what we called “microbes that masquerade as minerals” to see how extensive the microbial presence is in these secondary mineral deposits. It turned out, it’s quite substantial. So that blue-green mineral you mentioned um… contains a lot of toxic copper. And one of Kenneth’s photos of it actually made the cover of Astrobiology where we published an article. So, why would those organisms be in there if it’s toxic? Because the deposits are teeming with microbial life. We were attracted to these because of their color, but we started looking at all the other types of secondary mineral deposits and we’re finding evidence across all those sample types that microbes cycle nitrogen – which is a key element for life and the other life in lava caves. We also find that some of the microorganisms may use sulfur, or iron, or manganese as energy sources. There much better at expanding what they can eat. So, there’s a lot of diversity to this and many of them are organisms that we don’t yet really understand what they eat and what they do.
Ranger Dean: This is really an amazing story as it unfolds. So, in my profession of conservation biology, molecular biology and genetics just rewrote the book for us. We started to see what things were related to – even if they didn’t look like each other. So, you were using a combination of scanning electron microscopy and molecular analysis, and you dove deeper to reveal something amazing. Both the microbial mats and the secondary mineral deposits were teeming with life – it just wasn’t life as we normally know it. So, I was reading about this last night and it just blew me away. Tell me a little bit about the diversity of these novel species.
Diana: That’s truly amazing and it has changed over the years as we went from, I’m going to call them primitive molecular sequencing techniques, to really advanced. So, I went from getting a hundred at most, genetic sequences out of a sample to getting sixty-thousand sequences. And what that is telling me is who are the dominant organisms that are there. One of the ones I’m most intrigued by is what’s called the Archaea. And so, this is one of the domains of life. We used to call them just the “extremophiles.” And they are now being explored for who they are – and a whole bunch of them have newly been named in the last ten years. In the lava caves, were finding a lot of them. It’s like your peeling back the curtain over the microbial world. And in caves, we’re finding that there are many organisms that help maintain the rest of the cave ecosystem—so this is a new area of study because we’ve just sort of said, “Okay, microbes are there. What are they doing?” We don’t really know but some of them are what are called autotrophs. Instead of getting their carbon from organic matter – like what you may have had for lunch or dinner or breakfast, they are fixing (i.e. sort of a converting) carbon dioxide in the atmosphere to organic carbon, and that can become the basis of energy for other organisms in the cave.
Ranger Dean: So, I know we’re going to have a lot of interest in this just because these things really haven’t been studied to this depth before. So, what we’re going to try to do is put up some of the scanning electron microscopy photos of these incredible life-forms up on this same page with the podcast. And you knew we couldn’t do this podcast without bringing your research and findings to the implications for life on other planets. It’s appropriate that we’re recording this podcast just a few days after Perseverance has made a successful landing on the surface of Mars.
Ranger Dean: I was reading your article in Astrobiology and I can see why researchers draw so many parallels between Mars and parts of Hawaii. NASA has tested their Mars rovers on both Mauna Loa and Kīlauea volcanoes because of the phenomenal similarity of landscapes. So, the big question, does Mars have lava caves and just what are the implications for finding life, or at least a record of life there?
Diana: To me, this is a really exciting area of study. We’ve known for a while that there are lava caves on Mars, in fact there was a study by Glen Cushing that published… was published in 2007, where he documented some of the findings just a few years before from one of the Mars expeditions. There’s also evidence on other extraterrestrial bodies in our solar system that there are lava caves on these bodies. So, there’s are some great images of these on the web, that if people want to look at them you can see. Also, my colleague Dr. Penny Boston, proposed way back in 1992 in an article, that the subsurface environments on Mars would be a really good place to search for evidence of past life. We had a conference last year in New Mexico where we discussed the possibilities of life on Mars and how to explore for it. And, we think that lava caves provide a protected environment in which early life on Mars could have survived, or left evidence that they were there. And that provides a motivation for exploring our lava caves in Hawai`i to identify the best candidates for a rover to sample on Mars and elsewhere. In fact, I’ve actually been part of a ground truthing experiment where I identified, on the wall of a lava cave, what I thought were good targets for the rover and then they would come along later to have the rover see if it detected the same target. So, it’s a great thing to explore.
Ranger Dean: This is great! It’s really right there on the edge of the frontier of discovery. I want to thank our guest today, Dr. Diana Northup, visiting Associate Professor, Biology and Professor Emerita, University of New Mexico. I know she was really busy. She was doing samples underground today. She’s doing the podcast now and she flies out tomorrow for other commitments but I’m so glad you took the time to talk with us today.
Diana: Dean, it’s really been a pleasure and I hope that this can excite other people about how cool life in a lava cave could be. They can look at them differently and think about what’s living on the walls of those caves and enjoy the possibilities.
Ranger Dean: This is great. It also shows how our national parks and the resources within them can be such an amazing source of research and discovery. Also, I want to go..uh..a little bit off script here today to say, I know for the permits you guys got, you were very careful to make sure the resource was completely protected and was left in a pristine state as you left. I know, we went back in later. So, really, really a good way to care for the resource AND continue to learn. If you’d like to see the underground world of lava caves within Hawaii Volcanoes National Park, where some of this research was done. Kenneth has actually allowed us to post an incredible photo underground. We’re also going to post some of the scanning electron microscopy photos, so that you can meet some of these cool life-forms up close. Until next time, I’m Ranger Dean wishing you a safe visit to your national parks.
Description
Today, researchers around the world are surveying some of the harshest environments on the planet searching for “extremophiles” and finding life in the most unlikely of places. Researcher Dr. Diana Northup explains how life found a way in these extreme conditions.
Credit
NPS Podcast
Date Created
03/10/2021
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