Deforestation Leaves Fish Undersized And Underfed

The role forest matter plays in aquatic food chains is a relatively recent discovery

Deforestation is reducing the amount of leaf litter falling into rivers and lakes, resulting in less food being available to fish, a study suggests. Researchers found the amount of food available affected the size of young fish and influenced the number that went on to reach adulthood. The team said the results illustrated a link between watershed protection and healthy freshwater fish populations. The findings have been published in Nature Communications.

“We found fish that had almost 70% of their biomass made from carbon that came from trees and leaves instead of aquatic food chain sources,” explained lead author Andrew Tanentzap from the University of Cambridge’s Department of Plant Sciences.

“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,” he added.

Size matters

Dr Tanentzap observed: “Where you have more dissolved forest matter you have more bacteria, more bacteria equals more zooplankton.

“Areas with the most zooplankton had the largest, fattest fish,” he added, referring to the study’s results.