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Banana farms are bad for crocodiles, scientists say

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A photo of a spectacled caiman (Caiman crocodilus).Paul Grant

Shoppers spend an estimated $15 billion on bananas each year world wide -- and demand for the toothsome treats spells trouble for Central America's crocodilian population.

Heavy rainwater washes pesticides used in plantations into the water streams in protected conservation areas where endangered caiman species live. A new study published in Environmental Toxicology and Chemistry studied 14 adult caiman -- kissing cousins to crocodiles and alligators -- and analyzed their blood for traces of 70 types of pesticides.

"Banana plantations are big business in Costa Rica, which exports an estimated 1.8 million tons per year; 10 percent of the global total," author Paul Grant from Stellenbosch University, South Africa said in a statement. "The climate of the country's North East is ideal for bananas; however, the Rio Suerte, which flows through this major banana producing area, drains into the Tortuguero Conservation Area."

Caiman near the Rio Suerte were found to have higher levels of pesticides in their blood streams. Nine pesticides in total were detected in the caiman blood. Of these, seven were listed as Persistant Organic Pollutants (POPS), banned under the 2011 Stockholm Convention.

"Caiman near banana plantations had higher pesticide burdens and lower body condition," Grant explained. "This suggests that either pesticides pose a health risk to caiman, or that pesticides harm the habitat and food supply of caiman, thereby reducing the health of this predator."

Caiman have long sat on top of the food chain and provide an integrated assessment of the damage pesticides cause throughout the ecosystem.

"Caiman and other aquatic species have been exposed to pesticides from upstream banana plantations, even in remote areas of a national wilderness area," concluded Grant. "Banana plantations may be economically important to Costa Rica; however their erosion of aquatic ecosystems highlights the need for a developed regulatory infrastructure and adequate enforcement."