To Compare or Not to Compare

During our time in Panama, we had the chance to meet with distinguished researchers from different fields of ecology. Many of them highlighted the importance of carrying out comparative studies -be it comparing different bird species, contrasting forest plots or distant coral reefs. Even though these types of studies might sound extremely hard to set up, the information we can learn from them are totally worth the effort.

Coral covered by brittle stars, Ophiuroidea (Photos by Brandon Varela)

Measuring coral reef biodiversity can be tricky, because of the 3D nature of these ecosystems. One of the sampling methods commonly used to estimate biodiversity in coral reefs entails collecting coral rubble (pieces of dead corals). Even though you can break the rubble into pieces and find a myriad of macro-invertebrates, it is difficult to standardize sampling. In other words, all pieces of rubble are structurally different. Some pieces of rubble have more holes and crevices for crabs, shrimps, fish and more critters to crawl in than other.

The solution Dr. Nancy Knowlton’s lab found was to create a series of reef condominiums, known as ARMS (Autonomous Reef Monitoring Systems). These plastic structures are strategically planted in different coral reefs around the world and are left there from 1 to 3 years. Both mobile (for example, crabs and shrimp) and sessile (like algae and sponges) organisms colonize the ARMS. After retrieving the ARMS, researchers can have a better idea of the biodiversity found in that coral reef. The organisms found in the ARMS are also barcoded, and thus far ~90% of the species found were not present in databases!

Using a combination of standardized sampling methods, comparative studies and molecular technologies makes it possible to start asking questions that we could have only dreamt of a decade ago.

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