Seas of the small
Most of marine biomass belongs to microbes, which comprise as much as 90 percent of total sea life mass, according to the new report. Ann Bucklin, a professor of marine sciences at the University of Connecticut and co-chair of the census's zooplankton project, and her colleagues worked to catalogue what she calls "the hidden diversity."
Whereas many estimates about zooplankton had been based on biomass or functional groups, she has been trying "to put species back in the equation," she says. Armed with a DNA barcode scanner and what she describes as "monster butterfly nets" to capture some of the smallest sea creatures thousands of meters below the surface, their group was able to rapidly sample and document new species and their distributions. "We saw animals alive that no one has ever seen," she says. Pulling up the nets filled with so many rare denizens of the super-deep, she says, was "mesmerizing." She recalls, "We had people jumping up and down saying, 'I've never seen a sample like this.'"
High-throughput DNA sequencing allowed the researchers to get a quick read on genetic material across a large sea sample. But these technological advances are no replacement for traditional taxonomy, Bucklin says. "We still need taxonomists to be able to describe these species and help us understand what's new," she says. However, with only 23 taxonomists on the steering committee in her field—and few students pursuing the work nowadays—she is afraid that "we are losing that expertise…the accumulated knowledge of what's a species."
After cataloging, Bucklin is looking forward to moving beyond the baseline. "We're finding huge numbers of new rare species distributed throughout the ocean," she says, noting that the census data have emphasized that "species are everywhere—and they're rare everywhere." And she wants to know why biodiversity is important. The multitude of species is "beautiful," she says, but "I want to know what they're doing…why in the grand scheme of things" it makes a difference if there are 14 species of plankton in an area rather than seven.
An ocean of data
One of the most difficult aspects of the endeavor, Ausubel says, was keeping all of the teams and researchers focused on the collective goal—and coordinating the flood of data. He compares the experience to "a funny movie from the 1930s where you have a switchboard" and are trying to stay afloat amid a constant rush of new input. His work sometimes came down to a comical roll call, he says, in which he had to ask, "Okay, cephalopod people, what's your number? Sponge people, what's your number? Annelid people, what's your number?"
In addition to new data coming in from sampling and surveying, he points out, there were also noticeable changes occurring during the decade of the census. The most apparent changes, he says, were in the polar regions, where ice has been retreating. In Antarctica, he notes, "we were there to observe large herds of sea cucumbers moving into areas that had been ice-covered" in previous years.
Climate change, however, is currently only third on the list of the biggest current threats to marine life, Ausubel says. "The number-one threat is direct removal of marine life"—overfishing—he says. The second most severe is destruction of habitat, such as development-driven changes in costal areas and wetlands. But changing climate will be of increasing importance in years to come, and its specific impacts remain unknown. "Climate change will reorganize life in the oceans," Ausubel says, quickly adding, "We don't know how."
Despite many disheartening long-term trends, including coral reef loss and continued overfishing, some success stories have also become evident. "Some of the marine mammals have certainly come back in considerable numbers," Ausubel says. The lesson to be learned, he notes, is that "if we leave areas alone for a reasonable amount of time," many of the species will rebound. However, protected areas rarely recover into an ecosystem that looks like it did before, and instead go through marked "regime changes," he notes.
If anything, the census has opened a proverbial new can of marine worms, leaving scientists anxious to go on with the work.
Many of the researchers are hoping to continue the effort into another decade and will be discussing the plan Thursday in London and again next fall at the World Conference of Marine Biodiversity in Aberdeen, Scotland.
"Are we done?" says Bucklin, reflecting on the marine census. "No. Are we close? No. But boy, did we get a hell of a lot done."