Endangered: The Deepwater Tahoe Stonefly

A stonefly, waiting to be eaten by some cruising fish.

Although I spent many summers in my early youth on the shores of Lake Tahoe, I never encountered the Tahoe Stonefly. Neither had anyone else in those days—not just because it’s found at depths of 200-270 feet (60-80 meters), but it wasn’t even discovered until 1963. Capnia lacustra, now endangered, is only found in Lake Tahoe. It is one of two stonefly species that lives its entire life cycle under water, collecting, shredding, and consuming algae, plant material, and detritus. 

It made the endangered species list due at least in part to “cultural eutrophication,” a form of water pollution that occurs when excessive fertilizers run into lakes and rivers. This encourages the growth of algae and other plants, which cause overcrowding as plants compete for sunlight, space and oxygen. 

Stoneflies performing a little synchronized swimming.

Who loses? The Tahoe Stonefly. You might not think this is a big deal; but Stoneflies are integral and important food web components of most stream ecosystems throughout the world and therefore are almost exclusively beneficial insects. All stone flies are intolerant of water pollution, and their presence in a stream or still water is usually an indicator of good or excellent water quality.  


Sources

Endangered species international
Life in fresh water
What When How: Insects
NW Nature
The endemic deepwater stonefly in Lake Tahoe
Beneficial Bugs