Photograph by John Cancalosi, National Geographic

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A spectacled caiman, Caiman crocodilus, sits partially submerged in water. Pesticides are threatening the Costa Rican caiman population.

Photograph by John Cancalosi, National Geographic

Demand for Bananas Puts Costa Rica's Caimans at Risk

Pesticide concentrations are higher in caimans near banana plantations than those farther downstream.

Bananas are big business for Costa Rica, bringing in hundreds of millions of dollars each year. But the bright yellow fruit could spell trouble for the country's caimans, a crocodile relative.

New research from the journal Environmental Toxicology and Chemistry found that spectacled caimans (Caiman crocodilus) near banana plantations were significantly thinner, and had higher pesticide concentrations in their blood, than caimans in more remote locations. (Watch a video about banana farms in Costa Rica.)

"The animals are very, very thin—about 50 percent thinner than those away from the plantations," said study co-author Peter Ross, an aquatic ecotoxicologist and associate professor at the University of Victoria in British Columbia.

It's unclear whether the pesticides are directly toxic to the caimans or are impacting their health indirectly by diminishing the quality and abundance of their food supply.

Ross thinks the latter scenario is more likely given the moderate pesticide concentrations he and his colleagues found. Since all of the pesticides detected were insecticides, the chemicals could be knocking out the bottom of the food chain. This would affect the fish that eat the insects, resulting in caimans having to search farther for food and use more energy to try to find the few fish that remain.

A Banana Bounty

With its warm temperatures, bountiful rainfall, and good soil, Costa Rica is a prime location for banana production. As a key export, bananas play an important role in the nation's economy. In 2011, Costa Rica exported 2 million tons (1.9 million metric tons) of bananas, valued at over $700 million.