The public hears of a changing seascape, mostly from pollution or climate change. But there are disturbances in deeper waters as well, and that’s where Lisa Levin points her camera.
Levin, director of the Center of Marine Biodiversity and Conservation at the Scripps Institution of Oceanography, focuses on one part of the ocean we can’t see: the continental margins. During the past 25 years, she has studied regions of the ocean naturally deprived of oxygen, between 200 and 1,000 meters deep. These bands, or oxygen minimum zones (OMZs), contain less than 90 percent of the oxygen found at the surface—and significantly less life. Now these areas are starting to expand worldwide.
Levin’s recent papers have promoted a more protective view of the deep sea. “There weren’t a lot of such papers ten years ago," she says. "Even I wasn’t thinking about it.” But her study sites started showing evidence of direct impact from human activity, and she now fosters a sense of stewardship in her talks. She has begun to engage the public on this ocean realm, and she endeavors to help other countries manage their deep resources.
During the February 2012 meeting of the American Association for the Advancement of Science in Vancouver, Canada, SciCom’s Amy West spoke with Levin over breakfast before her symposium to discuss the altering ecology of the deep ocean.
This field was not easy to get into as a woman 30 years ago. What helped you enter the deep-sea world?
I started as a graduate student at Scripps in 1976. I was 21. Hydrothermal vents had just been discovered. That excitement was infectious, and I became fascinated. Scripps was one of the few places doing deep-sea biology, and that gave students incredible opportunities. My deep-sea dissertation was actually on tidal flat ecology, but I and another student got $5000 to experiment on how fast animals colonized deep-sea sediments. I was in a great window for women in academia; the women I graduated with at Scripps have all been successful.
You also work in shallow water?
The ecological principles are the same; they feed each other. But the deep sea inherently is fascinating. It feeds the curiosity-driven part of me, the part that loves discovery, novelty, and awe. Every time we go to a new place, we bring up things nobody’s seen before, and that is incredibly exciting. Going to sea is an escape from the lab and demands of day-to-day life. That’s very rejuvenating.
"We have to set aside conservation areas. We have to give industry a sense of responsibility for these systems. They are not there simply to be plundered."
How many hours or days do you think you’ve spent in manned subs?
I’ve probably been on 75 dives as a rough estimate, but I honestly don’t know how many.
With such limited time in research dives, do you feel it’s difficult to get that big picture view of the true issues in the deep sea?
I do think it is hard to get the big picture. All the new acoustical tools allow us to get a more comprehensive view, but they don’t provide images of the organisms specifically. We are doing the best we can, but we’ve seen less than five percent of the ocean floor, and we've studied less than one percent.
What have you seen change over time at your dive sites due to human impact?
The sites I’ve visited most are off California and Oregon, and those sites show an increase in fishing effects. I’ve had my experiments upended by trawls, we've encountered ghost fishing nets, and we've seen fishing boats everywhere.
What's the most interesting thing you’ve come across?
One of the most interesting is something we found at 1,850 meters off Costa Rica, called a hydrothermal seep—an ecosystem halfway between a hydrothermal vent and methane seep.
Is that the first time a hydrothermal seep has been observed?
Actually an Alvin pilot noticed shimmering water coming from the base of a tubeworm bush. We put in a temperature probe and found warm water. The scene looks very vent-like, but it’s in a setting full of methane seeps—it’s warm, but full of methane. We wanted to call it a “veep.” Scientists studied these habitats separately, even though the organisms are similar. But the more settings we discover, the more we realize they are not so separate.
Can you see oxygen minimum zones?
I have been studying them for decades, but had never actually seen them with my eyes. In 2008 I was able to make a dive off India between 700 and 900 meters at the lower boundary of an OMZ. I knew the larger organisms are zoned, so to cross those zones and see the biology change with my own eyes was pretty awesome.
Aren’t OMZs natural? Do you think their expansion is manmade or natural?
It’s hard to study without a long time series. The current understanding is that adding carbon dioxide has accelerated the rate of ocean warming [warm water holds less oxygen] and the melting of the polar ice caps. Both of those enhance layering in the ocean, a layering that reduces the vertical mixing. Normally oxygen enters the deeper ocean by mixing. Respiration in the ocean is also continually depleting that oxygen.
There’s no longer any vertical mixing?
There’s less. And that is causing oxygen to not be completely replaced when used up. Our understanding is that it’s leading to an expansion of OMZs at a pretty rapid rate. No one knows exactly if this is part of some long-term cycle. The belief is that things are going in one direction, and it’s being accelerated by humans.
How does that chunk of deoxygenated water affect life? Can animals swim up through it?
Some animals can’t tolerate the OMZ conditions and live above it. As the upper boundary of this layer moves upward, those animals are pushed into shallower waters. Plankton that live in OMZs by day migrate up at night to feed. But as they move up, they have further to go to oxygenated waters. With warming and acidification in surface waters, their window of suitable habitat is shrinking from both directions.
There has been evidence that fish like sole and rockfish are losing the bottom end of their habitat range. Some are moving north where there is more oxygen. Species that can’t move probably die or suffer in some way.
I care and you care, but why would my mom care about these areas?
Deep-water fisheries. Climate regulation. Biodiversity. Oceans control climate by drawing down carbon dioxide from the atmosphere for plankton and photosynthesis, which then sinks to the seafloor. The deep ocean plays a critical role in that carbon burial. We are also starting to find pharmaceuticals and other applications for deep-sea organisms. In the field of bioprospecting, bamboo corals have been discovered as good bone replacements [as materials that would be synthesized artificially]. Climate change and human activities could easily destroy components of biodiversity before we find their beneficial uses.
But in essence all the bioprospecting and exploration benefits humans.
The movie Avatar is a perfect analogy for what we are poised to do in the deep ocean with mining. We don’t understand the ecology and all the deep-water connections, or the way the deep ocean functions in the health of our planet. I think we know it’s important, but we don’t know all the linkages.
People have a hard time when it’s out of sight, out of mind. If you could do a public service announcement about the deep sea, what would it be?
I am conflicted because I'm meeting with Nautilus Minerals tomorrow to talk about monitoring in deep-sea mining. I am of the opinion that scientists have to engage with industry. The deep sea is not going to remain the domain of the ivory-tower academicians or curiosity-driven researchers. There are too many resources down there. The threat is especially severe in less-developed countries that need the money and have the resources. I don’t want to actually promote mining, but if it’s going to happen, we have to ensure the environmental work is first rate. We have to set aside conservation areas. We have to give industry a sense of responsibility for these systems. They are not there simply to be plundered.
I feel your passion. You can’t protect these unseen areas.
It’s scary. It’s really scary [voice cracking]. I came away after six months on sabbatical in Namibia and realized they have two environmental lawyers in the entire country, and no deep-sea biologists. They had leased tens of thousands of acres of deep seafloor for phosphate mining without any relevant biological research being published. Climate change and direct human activities are going to affect the ability of these ecosystems to recover.
Do you think it’s too late to reverse the impacts?
No, I think it’s the right time, because deep-sea mining hasn’t happened yet. Some of the impacts like deep-water trawling, however, are quite severe already. Five years ago, while exploring off New Zealand, we found the first methane seeps, full of new and exciting species. Every single site had been subject to trawling; one of those sites had been trawled 200 times. Governments can outlaw trawling and allow communities to recover.
You don’t think it’s a function of visiting more sites?
No, human impacts have changed over the last 30 years. We have moved deeper and deeper with oil and gas extraction, with fishing, and now we are poised for mining. Those are the big three. If you look at where people fish, it’s deeper and deeper every year. More than 4,000 [drilling] rigs exist in the Gulf of Mexico, and they are getting deeper [more than 3,000 meters]. Until the Deepwater Horizon blowout, people weren’t even thinking about them as a form of disturbance.
Do you feel like a pioneer in this field?
No. I feel like there are many great scientists working in the deep sea. I do feel like our challenges are really daunting, and I am not sure of the best approach. I know that public awareness has to be part of the solution.
Is that why you’ve taken an interest in science communication?
I think the public is inherently fascinated by what’s there. My former student had his paper with video come out on the dancing Yeti crab, and within a week on YouTube there were 40 versions of the Yeti dance set to popular songs. The public had a great time with it.
Is the concept of OMZs too technical for people to grasp?
There’s real power in a phrase that captures an idea that people repeat. The term “ocean acidification” is not accurate, but it’s an idea. It caught on like wildfire partly because there is a clear term to express that concept. So “deoxygenation” was introduced. At first I objected, but then I realized we need a word. We need to raise consciousness: the ocean is losing oxygen, and it’s a big issue too.
Amy West, a graduate student in the Science Communication Program at UC Santa Cruz, earned her bachelor's degree in marine biology at the University of the Virgin Islands and her master's degree in marine science at the University of Otago, New Zealand. Her internships at UCSC have included the Monterey Bay Aquarium Research Institute news office, the Monterey County Herald, and KUSP-FM public radio. This summer, she will produce videos as a multimedia intern for the Golden Gate National Parks Conservancy in San Francisco.
© 2012 Amy West