Immersed In an Exotic Lab
For two years now, international teams of scientists have been combing the land and waters of the French Polynesian island of Moorea, working to create the world's first complete DNA inventory of a complex tropical ecosystem. The biologists and ecologists have climbed the island's jagged mountains, hiked its tropical forests and dived to its abundant coral reefs, accumulating samples of every species of plant, animal and fungi on the 1.2 million-year-old volcanic island.
But when CUNY assistant professor of biology Michael Hickerson and three of his students from Queens College and the Graduate Center spent two weeks on Moorea this summer, they did their hunting in some less-than-exotic places. Searching for sea creatures, they spent days underwater near manmade habitats -- wood docks and pilings, stone sea walls and, as Hickerson put it, "sneakily snorkeling" under expensive hotel bungalows suspended over the water.
"We spent several hours underwater with our knives and bags in hand, scraping off ascidians, sponges and bryozoans -- as well as a giant oyster that we think had 20 or 30 species living on its shell," Hickerson, a computational biologist, wrote one day in his blog on the University's Decade of Science website.
But the mother lode may have been what he and his team found clinging to tires tied to docks and used as bumpers for boats. Unlike fixed structures, the tires rise and fall with the tide and their treads become encrusted with countless species, while the inside scoops up everything from butterfly fish to peanut worms to sea cucumbers to a candy cane-patterned coral-banded shrimp. Even a small octopus.
Hickerson and his team -- Graduate Center student J.T. Boehm and Queens College undergraduates Francois Desinor and Chris Ludvik -- were part of an ongoing international effort called the Moorea Biocode Project that is using a technique known as DNA "barcoding" to identify species and perhaps even discover some new ones. The process involves taking samples of all non-microbial life found on and around the island and extracting mitochondrial DNA, which varies significantly between species.
The project began in 2008, and thus far more than 100 evolutionary biologists and ecologists from many institutions have taken part.
Hickerson and his CUNY team is focused especially on building the database for "invasive" or "colonial" species -- those that are not native to Moorea and presumably arrived at some point in history in the ballast water of cargo boats. "Many very small creatures, including larvae, can be very difficult if not impossible to identify at the species level," Hickerson says. "But we can use the DNA biocodes to identify them and measure the exact level of biodiversity. Most important, we can use it to detect invasive species that may have gone undetected."
The data could be critical to investigating how climate and oceanographic changes are altering the food chain and the species pool itself. Hickerson and his team are focusing on banded pipefish, a species commonly found in Moorea's abundant coral reef. By collecting DNA biocodes from what they find in the gut of the fish and comparing it to biocode database already collected, the researchers hope to obtain much more accurate estimates of the species' diet. And that would allow ecologists to obtain something they have long sought: a full picture of what they call "food web architecture."
After each excursion during their trip, the CUNY researchers returned to the Moorea lab to record their catch and prepare each species for DNA extraction and sequencing.
"All told, we processed nearly 400 different species," Hickerson said upon his return to New York, "and we suspect that several of them are non-native."
The sequencing will be done closer to home -- at the Smithsonian Institution in Washington. Grad student Boehm brought the samples with him in his luggage and delivered them personally to the DNA lab at the Smithsonian.
All of this leads to the core of Hickerson's expertise. He is developing computational tools to help understand how Moorea -- or any other island with a complex ecosystem -- becomes occupied by all its species, whether native or invasive. A moving volcanic hotspot formed all the Society Islands, nearby Tahiti emerging some 600,000 years later than Moorea. Thus, says Hickerson, "We can use all the biocode data to reconstruct how species from Moorea colonized Tahiti."
But the implications go far beyond these islands in the South Pacific. "Ultimately, the aim is to collect this type of genetic data from every species on the planet," Hickerson said. "This will be extremely useful for all sorts of applications, ranging from the identification of species to the discovery of new ones -- from estimating levels of biodiversity to reconstructing evolutionary history, and understanding the dynamics of species invasions.
- It's considered a natural laboratory, a complex ecosystem ready-made for biological and ecological study.
- Moorea was formed by volcanoes 1.2 million years ago and has high mountains, lush forests and a well-developed coral reef and lagoon system.
- The biocode project is centered at a well-equipped lab, called the Gump Research Station, run by the University of California, Berkeley.