Forest Loss May Starve Fish: Tree Debris Feeds Aquatic Ecosystem

It goes to show that our planet is interconnected in ways that we might never expect. Researchers have found that logging and forest loss is actually starving fish. How? The lack of forest debris that washes into freshwater lakes is stymying the growth of microscopic zooplankton, which provide a major food source for fish.

The researchers wanted to assess a Canadian lake that had previously suffered an ecological disaster; acid rain caused vegetation to die back, which meant that these days the area surrounding the lake has varying degrees of forest coverage.

Carbon from forest debris actually has a different elemental mass than carbon produced by algae in the aquatic food chain. By analyzing young Perch that were born that year, the scientists were able to determine how much of their mass came from forest vegetation, and how much came from the aquatic food chain.

"We found fish that had almost 70 percent of their biomass made from carbon that came from trees and leaves instead of aquatic food sources," said Andrew Tanentzap, one of the researchers, in a news release. "While plankton raised on algal carbon is more nutritious, organic carbon from trees washed into lakes is a hugely important food source for freshwater fish, bolstering their diet to ensure good size and strength."

That's not all that the researchers found, either. It turns out that at least 34 percent of fish biomass comes from vegetation, and increased to 66 percent in areas surrounding rich forest. They also found that fish were fatter in areas where there was more forest coverage around the lake.

"More than 60 percent of the world's fresh water is in the boreal areas such as Canada, Scandinavia and large parts of Siberia," said Tanentzap in a news release. "These areas are suffering from human disturbance such as logging, mining, and forest fires resulting from climate change-all occurrences predicted to intensify in coming years."

The findings reveal how forest coverage is important not just for animals on land, but also crucial for fish health. By preserving forested areas, conservationists can help nearby freshwater lakes.

The findings are published in the journal Nature Communications.