More carbon emitted when top predators removed from food chain VICTORIA, British Columbia, Feb. 20 (UPI) -- Freshwater ecosystems emit a lot more carbon dioxide into the atmosphere when predator animals at the top of a food chain are removed, Canadian ecologists say. Predators' diets consist either directly or indirectly of all the smaller animals and plants in an ecosystem, researchers at the University of British Columbia say, and the smaller animals and plants play a big role in sequestering or emitting carbon. Trisha Atwood, a doctoral candidate in the university's Forestry Department, and colleagues report that when they removed all the predators from three controlled freshwater ecosystems, 93 per cent more carbon dioxide was released into the atmosphere. "We knew that predators shaped ecosystems by affecting the abundance of other plants and animals but now we know that their impact extends all the way down to the biogeochemical level," Atwood said. "People play a big role in predator decline and our study shows that this has significant, global implications for climate change and greenhouse gases," she said. The study was reported in the journal Nature Geoscience.