Story and photos by Doug Jackson
Have you ever noticed those small ponds of water tucked away amongst the trees while walking through the woods?
Or have you ever heard a chorus of quacking that sounds like squeaking balloons echoing from within the forest in mid-spring?
Then you have most likely encountered one of Michigan’s many special wetland ecosystems known as vernal pools.
If you don’t realize what you’re viewing, it would be easy to dismiss these unassuming wetlands as just big puddles, small ponds, or swamps in the woods. But there is much more to these woodland wonders than just water and mucky soil.
These pools are ephemeral, in that the depressions they lie in are usually filled with water temporarily from winter until mid to late summer, and are typically dry, or mostly dry, throughout the fall.
Easily overlooked and unappreciated, vernal pools are threatened ecosystems that support a wide variety of wildlife, including some that depend solely on these pools for survival. The unique and diverse range of wildlife supported by vernal pools has lent to their nickname of choral reefs of the Midwest. And because these are wetlands, they play a vital role in purifying and recharging ground water that we humans depend on.
The quacking choruses we hear each spring are the mating calls of the Wood Frog. After thawing from a frozen state over winter, these frogs return in great numbers to the same vernal pools every spring to mate and spawn.
These pools become filled with Wood Frog tadpoles by late spring.
Other amphibians that depend on vernal pools are the Spotted and Blue-spotted Salamanders. These, too, return to the same pools each year to reproduce, filling their pools with salamander tadpoles for a good part of the summer.
There are clams that grow here too; little tiny clams, no bigger than a fingernail, appropriately called fingernail clams. Did you think you’d ever find shrimp in the woods of Michigan? There is actually a crustacean that is related to brine shrimp that only lives in vernal pools. These have the fantastical name of Fairy Shrimp, because they seem to appear out of nowhere and swim effortlessly in the water upside-down.
These amphibians and crustaceans are able to thrive in these temporary pools because fish are not able to live in them and, hence, unable to prey up their eggs or larvae.
It is fascinating to learn about these pools and discover all that lives in and around them.
Unfortunately, vernal pools have many threats facing them, including human developments, pollution, and climate change. There are laws, both federal and state, that protect most wetlands these days. However, due to the size and location of vernal pools, they do not fall under these protections.
Information about these pools is still limited with not much data on them. There is much to learn and to do to protect these delicate and easily misunderstood wetlands. Easy steps we can take include good stewardship and keeping our feet and pets’ paws out of them. Another is to participate in the Michigan Natural Features Inventory (MNFI) citizen science program called Vernal Pool Patrol (VPP).
If you’d like to learn more about vernal pools and the fantastical critters living in them, as well as steps you can take to monitor vernal pools, contact the Eddy Discovery Center (https://www.michigan.gov/dnr/places/v-centers/eddy) in the Waterloo Recreation Area near Chelsea at (734) 475-3170 to sign up for a presentation on Sunday, Feb.19 from 2-3 pm.
More information on MNFI and the VPP, including how to sign up for online training classes can be found at https://vernal-pool-patrol-mnfi.hub.arcgis.com/.
