Enormous Fish, Tiny Plastics

At Adventurers and Scientists for Conservation, we work with high-level athletes and researchers who not only travel the world but also work to protect it at the same time. Biologist Lesley de Souza is one of these adventurers. On a recent trip to Guyana, where she studies migration patterns of giant arapaima fish, she collected water samples for our ASC Microplastics Project. Below, read about her incredible experience: 

I plunge my arm below the surface of the water, feeling the weight of the bottle increase as it fills with our first sample. The sun is relentless here at 3 degrees north of the equator, and my first impulse is to dive in and cool down, but I know black caiman, anaconda, sting ray, electric eels and piranha also take pleasure in these waters.

We are on southern Guyana’s Rewa River studying arapaima, one of the largest freshwater fish in the world. Arapaima often surface to breathe air, and their size—more than 10 feet long and up to 400 pounds—makes them an easy target for sight fishing and overharvest. Despite their threatened status, they are a sought-after delicacy in tropical South America.

I’ve spent the last three years studying arapaima movement patterns, helping inform managers about the need for protection. I work with the indigenous Rewa villagers and Rewa Eco Lodge, whose ban on commercial harvest has contributed to high arapaima numbers here.

​One of the most remote ecosystems left on Earth, the Rewa is a biodiversity hotspot harboring giant Amazon River turtle, giant river otter, jaguar, harpy eagle, goliath bird eating spider, giant armadillo and tapir. Even so, when I learned of the ASC Microplastics Project, I wondered if plastic was present in these waters. So, during a recent trip, photographer Zachary James Johnston and I collected water samples for ASC.

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Changing Planet


Meet the Author
Gregg Treinish founded Adventure Scientists in 2011 with a strong passion for both scientific discovery and exploration. National Geographic named Gregg Adventurer of the Year in 2008 when he and a friend completed a 7,800-mile trek along the spine of the Andes Mountain Range. He was included on the Christian Science Monitor's 30 under 30 list in 2012, and the following year became a National Geographic Emerging Explorer for his work with Adventure Scientists. In 2013, he was named a Backpacker Magazine "hero", in 2015, a Draper Richards Kaplan Entrepreneur and one of Men's Journal's "50 Most Adventurous Men." In 2017, he was named an Ashoka Fellow and in 2018 one of the Grist 50 "Fixers." Gregg holds a biology degree from Montana State University and a sociology degree from CU-Boulder. He thru-hiked the Appalachian Trail in 2004. Read more updates from Gregg and others on the Adventure Scientists team at adventurescientists.org/field-notes. Follow Adventure Scientists on Instagram @adventurescientists, on Facebook @adventurescientists, and on Twitter @AdvScientists.