September 1, 2010

Back from Moorea, and now the data

Assistant Professor of Biology, Queens College and The Graduate Center

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J.T., Chris and Francois head for a snorkel hunt

J.T., Chris and Francois head for a snorkel hunt



We’re back in the Big Apple.

Sadly, we left Moorea the day before the big performance by the “Tahitian Elvis” in one of the hotels. But we were happy to know that we collected a large amount of data for analysis.

For the last few days of our field expedition, we were extremely busy gathering species from more sites on the island so we could have sampling points across the entire coastline of the island. We combed the full range of manmade habitats, including sneakily snorkeling under expensive hotel bungalows that are suspended over the water. We took samples from piers, rock walls used to shelter small harbors and dock pilings used by boats.

But the manmade structures that harbored some of the highest degrees of biodiversity turned out to be tires. They were tied to docks and used as bumpers to prevent damage to boats. But to marine animals these tires provide the perfect place to call home. The tire acts as a substrate for a wide array of taxonomically diverse sessile animals (i.e. barnacles that stay attached to a surface) and on the tires of Moorea we found sponges, bryozoans, polycheates (segmented tube worms), colonial ascidians, bivalves (i.e. oysters and clams), and anemones. Why do tires provide such good habitat? Well, unlike other fixed structures, tires rise and fall with the tide and therefore are permanently available for sub-tidal species that normally live at much greater depths. From our observation these tires were heavily encrusted with various bivalve species, which provide an additional “base” habitat for other species to begin to inhabit.

Not only did we find a wide variety of sessile animals, on some of the tires we found several species of fish (damsel fish, butterfly fish and pipefish) as well as a small octopus. These were scooped up in the inside of the tire as we lifted it out of the water. We also found peanut worms, brittle stars, sea cucumbers, large flatworms, nudibranchs (sea slugs), numerous crabs, nemerteans and a pair of candy cane-patterned coral banded shrimp. All in all, each tire contained a dozen animal phyla (phyla are primarily the highest level category used for classifying animals into taxonomic groups).

But what about the invasive species? Detecting invading species can be a tricky business and this is especially the case for small marine invertebrates that might be hard to identify (and for many taxonomic groups there are only a few experts who can do the job properly). One of the motivations behind the DNA Biocode program is purely practical. Instead of having to rely on the taxonomic expertise of a few individuals scattered across the globe, we hope that the genetic data we generate will associate our collected specimens with previously collected individuals whose species membership is known. In a few weeks, the genetic data from all 390 individuals we collected should be ready for analysis and we will then finish writing up a paper describing the process behind detecting new species using this automated method, as well as reporting on what new species have been detected on the island.

Subsequently, our findings can be used to test ecological models that predict the stability of species interactions and how novel invasive species affect the structure of marine ecological communities.