Microorganisms use floating plastic trash as rafts to ride the ocean’s currents. Some of those creatures could cause human disease, while others threaten to invade other ecosystems.

A recent study of plastic debris populations found at least 1000 individual species of microbes on millimeter-sized scraps of plastic bobbing in the North Atlantic. The floating garbage created an ecosystem scientists dubbed the “plastisphere.”

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“The organisms inhabiting the plastisphere were different from those in surrounding seawater, indicating that plastic debris acts as artificial ‘microbial reefs,” said Tracy Mincer of Woods Hole Oceanographic Institution, co-author of the study published in Environmental Science & Technology. “They supply a place that selects for and supports distinct microbes to settle and succeed.”

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Some of the plastic rafts were dominated by species from the bacteria genus Vibrio. These  bacteria can cause intestinal diseases including cholera. Undercooked seafood can carry the bacteria. They also can infect open wounds and cause septicemia.

Besides the threat to humans, microbe stowaways could invade pristine environments.

A 2002 study, published in Nature, warned that plastic rafts carried non-native microbes to remote islands in the Arctic, Antarctic and everywhere in between.

IMAGE: Plastic garbage on the water’s surface. (Gary Bell/Corbis)