Drying Rivers, Dying Fish

Print Friendly
Brown desert with curved impression of riverbed, many streams branching off it

Brown desert with curved impression of riverbed, many streams branching off it Source: A river ran through it

The dry Colorado River delta in the Baja/Sonoran desert may leave a fascinating mark on the earth, but ecologists and fish are alarmed. Human use and climate change are draining rivers around the world, endangering fish and entire ecosystems in the process.

When rivers dry up, the food chain gets shorter, claims a study published an October 2010 issue of Science. Large-bodied fish, which are top river predators, cannot survive in the low oxygen-high temperature conditions of drought and thus perish.

Drought is not the only factor simplifying food chains. Increased flooding is also playing a role. Flooding creates higher flows, which “take out the middle men in the food web, making fish feed lower in the food chain,” said John Sabo, a biologist at Arizona State University and lead author of the report.

Still, the effects of drought are more catastrophic for fish and longer lasting.

As the lifeblood of ecosystems, rivers’ abilities to maintain their natural flow variations are important for their proper functioning, as the study indicates. An increase in droughts, which climate change research predicts, will not only threaten food chains, but also agriculture and recreation.