Friday, June 29, 2018

Happy Mayflies? Happy Lake Erie

by Sara Guiher, TMACOG Water Quality Planner

Very few of us welcome mayflies to our homes, places of work, cars (let’s be honest, they’re EVERYWHERE), with open arms. A large hatch like we’ve had this year might make you want to hide until it passes. But when it comes to the health of Lake Erie, mayflies are a good sign!

Mayflies spend most of their life in an aquatic environment such as a lake or river. The adult form that we are familiar with lives only long enough to reproduce after leaving the water. During their aquatic stage mayflies are intolerant of pollution and low oxygen. When Lake Erie received high levels of industrial pollution and sewage, these organisms could not survive in large numbers. When our lake was declared “dead” in the 1960s, mayflies were in the same place. Today’s issues in Lake Erie could also impact these sensitive species; large algal blooms can deplete oxygen in the water. But this year’s batch is good news about water quality, at least in early summer.

So next time you see a swarm of mayflies, hopefully you smile at their signal that hope is not lost for Lake Erie. Just remember: when you greet a cloud of our water quality friends with a smile, it’s probably not a good idea to open your mouth.

Here's some mayfly larvae collected by students in the 2017 Student Watershed Watch. 

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