The Hidden Biodiversity of the Ocean Realm
(Continued)
College research assistant professor Astrid Schnetzer (left) and postdoc Xuemei Bai collect water samples in the San Pedro Channel as part of a project in the Caron lab to monitor the presence of the algal species and associated toxins that form harmful blooms.
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Fuhrman’s team made a major discovery last year, when they found annual repeating patterns in the kinds and abundance of microbes at the site. They were able to relate these patterns to changing environmental factors.
Who’s there, Fuhrman said, “doesn’t change a huge amount from month to month. But two, three months later, the community has changed. And by six months, it’s a very different group. But by 12 months, the [original microbe groups] are back.”
That pattern, he said, supports the idea that microbes, like animals and plants, each have a specific biological niche.
“This conclusion shouldn’t be that earthshaking, but it actually is for some people,” said Fuhrman, who published the findings in the Proceedings of the National Academy of Sciences. “Microbes have their own, unique place in the world. It’s not the ‘if you lose one, another one’s fine, a dime-a-dozen’ kind of thing. They all have their own job. You wouldn’t see a repeating pattern if any one could do the job. It would just be random and change unpredictably.”
From Caron’s point of view, discovering the diversity of microbial life — the who — is one of the two most pressing questions in his field. The other is the where: Are some marine microbes found only in specific locales, or does the open nature of the oceans give most microbes a global reach, what he calls “cosmopolitan” presence? His work suggests it may be a mix. “I think that some organisms will have a discrete distribution, but we’ve already found that quite a few species do have a global distribution.”
Caron expects that, even for cosmopolitan species, their relative abundance will differ from place to place, depending on specific local conditions. “There’s usually a large suite of organisms at low abundance that can backfill (become more abundant) when and if environmental conditions change.”
In that way, the functions of the ecosystem can be maintained, even if the individual species shift. Caron likens it to a soccer game, with players substituting in and out. The individual players may change, yet the game goes on.
That’s why, Caron said, maintaining biodiversity — even of tiny microbes — is so important to marine health. “Microbes do the majority of the biological work in the oceans. They produce most of the energy and organic matter, and they decompose all of the dead organic matter. They support a wonderful and charismatic macrofauna, from shrimp to dolphins. What microbes do is fundamental to the way the oceans, and our entire planet, works.”
Molecular and genetic tools have enabled microbial ecologist David Caron to not only discover hundreds of new species of single-celled marine life, but also to better understand evolutionary relationships between them.
Photo credit: Don Millici.
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College research efforts in these crucial areas are set to expand. In fall 2006, seven new marine scientists joined the College faculty, recruited as part of an innovative “cluster hire” in environmental genomics and biogeochemistry coordinated by Michaels of the Wrigley Institute.
Among the new faculty are John Heidelberg, an associate professor of biological sciences, and his wife and colleague Karla Heidelberg, an assistant professor of biological sciences, who now live at the Wrigley Marine Science Center on Catalina Island with their two children. Both scientists have played key roles in large-scale, genomic studies of microbial diversity.
In March, the Heidelbergs and geobiologist Ken Nealson, the Wrigley Chair in Environmental Studies in the College, were among some two dozen co-authors of a report on the largest-ever global census of marine microbial life. The genomic study, published in the Public Library of Science Biology, revealed thousands of new and astonishingly diverse species. The team also described millions of new genes and proteins, some of which may prove useful in the creation of new antibiotics and alternative energy sources and in furthering our understanding of the role of microbes in global climate change.
New hire Katrina Edwards also studies microbial diversity, but in a largely unknown terrain — the rock below the sea floor. Since 2003, Edwards, an associate professor of biological sciences who was among the first anywhere to earn an interdisciplinary doctorate in geobiology, has been preparing to probe the biosphere scientists believe thrives underneath the ocean. In 2008, she will begin drilling to depths of 500 meters at a site in the tropical Atlantic Ocean.
Considering that soil holds the most diverse group of microbes on land, most believe that she will find a mother lode of new species in the sea subfloor. “No one’s ever done this before, so we really don’t know,” Edwards said.
Describing the extent of microbial diversity is not the only goal of these researchers. Most also want to apply what they learn to solve urgent environmental problems facing the oceans, and there are immediate practical applications too.
“So many of these microbial systems are incredibly important all over the planet,” said Michaels, listing pollution, bioremediation, climate change, corrosion, sewage treatment and biofuels as some areas where research on microbes may prove pivotal.
Geobiologist Katrina Edwards will search for new forms of microbial life in the rocky depths below the seafloor.
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For example, Caron’s new insights into the workings of normal marine communities will aid his research monitoring harmful algal blooms off the California coast. Algal blooms, which can prove fatal to marine life and cause millions of dollars in economic damage, begin when one species becomes overly dominant. Caron hopes to understand what factors tip the ecological balance.
Fuhrman’s genetic tests are already being used to test coastal waters for the presence of potentially harmful viruses — including enteroviruses and hepatitis viruses — and other human contaminants. “People have asked me for a long time, ‘Is it safe to go into the water?’
“If we understand how the natural ecology works, then we’ll have a better idea of what’s happening with these pathogens — in terms of how long they’ll survive in the water, what conditions promote them and what conditions inhibit them,” Fuhrman said.
College marine scientists still do much of their work at the old Hancock building at the center of campus — as well as aboard sea-going research vessels and in the labs at the Wrigley Institute’s island campus. In many ways, they are asking the same kinds of questions about biodiversity and the marine world posed by earlier faculty. But now, they’ve got better tools — and an ocean that needs help more urgently than ever before.
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