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Keeping Track of Invaders

 Invertebrate zoologist Jonathan Geller shows off the DNA sequencer used in his research at Moss Landing Marine Laboratories. Photo: Melissae Fellet

Invertebrate zoologist Jonathan Geller shows off the DNA sequencer used in his research at Moss Landing Marine Laboratories. Photo: Melissae Fellet

By Melissae Fellet | KUSP News

Many marine invasive species enter California from San Francisco Bay and then spread into the waters of the western United States. Identifying new invasions requires knowing what organisms are currently living in the state. A scientist is helping to refine lists of current invaders by identifying them by their DNA.

Even though invasive species can disrupt ecosystems, invertebrate zoologist Jonathan Geller doesn’t get mad when he sees them.

“They’re beautiful organisms in their own right,” Geller says. “They’re just in the wrong place. So I don’t really blame them for that. It’s human activities that have resulted from them being displaced from their native homes.”

Determining If the Regulation Works

Boats bring these invaders to San Francisco Bay, often carrying them on their hulls or in their ballast water. Proposed state regulations require boats to treat their ballast water, in hopes of preventing new invasions. Environmental monitoring is key to determining if a regulation reduces the rate of new invasions, Geller says.

Monitoring for new invasions requires knowing what invasive species are currently in the state. However, some of those existing invaders are unaccounted for, even though the Department of Fish and Wildlife has been tracking them for more than a decade. That’s because marine organisms can be tricky to recognize even with trained eyes.

“Some of these things are hard to identify simply because they’re not native here and so biologists on this shore are not familiar with them,” Geller says. “But what we also find is that things that look similar to each other may be genetically different.”

Those differences are unique markers for each species. In his lab at Moss Landing Marine Laboratories, Geller is working to connect the names of marine invertebrates to the unique DNA sequences that act as barcodes for each species. But making those connections can be challenging, especially when working with marine organisms.

“If it’s a whale or a cow or a mouse, there’s not much confusion about what organism [a DNA sequence] came from,” he says. “But there’s something like 10 million marine invertebrate species out there.” And for many of those species, their names or unique DNA sequences aren’t known, Geller says. “So it’s a work in progress to make the accurate identifications, get the DNA sequence that belongs to that organism and build this database and now everyone can use it as a tool as we are.”

A Database of Invaders

In 2009, the state turned to him for help identifying DNA sequences for invasive species growing on plastic plates in San Francisco Bay. Geller says these organisms are things that you would see growing on the side of a boat, like barnacles and sponges.

Taxonomists at the Smithsonian Environmental Research Center named the species they found on the plates and sent tissue samples of each one to Geller’s lab. Geller and his colleagues extracted two types of DNA from the tissue samples, copied the DNA and determined its sequence to get a genetic barcode for each species. Geller says that the database that they’ve built over the past three years linking species name with DNA barcode probably includes many of the existing invaders in the state.

“It’s grown the list of invasive species in California, not because more have actually arrived, but because now we’re aware that they’re actually here and they’re hidden as a group of species that we uncovered the members of those groups,” he says.

The list of invasive species around the state may grow again, as the project expands over the next four years to include sites up and down the coast.

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