What Are Vernal Pools, How to Help With Them

Editor’s note: This story was originally published in 2022.

With spring underway, it’s time to take a look at an ecosystem that only lasts for a short period of time called a vernal pool.

These bodies of water will dry up in the summer, but are necessary for some of the wildlife around Northern Michigan. People are slowly becoming aware of how important they are and how much we have to learn about them.

Vernal pools are large pools of water from melting snow and spring rain. These bodies of water contain a creature that exists nowhere else in Michigan.

“It usually holds water for about two months ore more. Fish can’t survive in them year round and fish tend to be these really voracious predators,” said YuMan Lee, conservation scientist at Michigan State University.

Without fish to eat them, ferry shrimp, a fresh water shrimp, can thrive in these environments.

“So they are these magical little creatures that show up when the pool fills up with water for a couple of weeks and lay their eggs and then they’re gone,” said Lee. “They only occur in vernal pools, you’re not going to find them anywhere else in any other habitat or ecosystem in Michigan so they are just really special places.”

Other species that depend on vernal pools are wood frogs and salamanders.

Salamanders will use vernal pools to lay their eggs. In some forests, there are more salamanders by weight than there are white tailed deer. They are a keystone species, meaning they are an important food source for other animals in the forest.

“They will go into the surrounding forest each system and provide food for a whole host of other animal species including raptors, herons, snakes, they are a silly important part of the food web in these forest eco systems,” said Lee. “Some have referred to vernal pools as the coral reefs of the north eastern forests because of the incredible diversity of animal species in particular, especially invertebrates and amphibians. You could just take one scoop of the net and find all sorts of little snails, fingernail clams and different larvae. We found, I think, over a hundred different invertebrate taxa already in vernal pools with just the little bit of sampling we have done in Michigan.”

Lots more work remains to be done though.

“So there are lots of things we don’t know about vernal pools, even just how to classify them or what are the different things that occur in them,” Lee said. “We don’t have a good idea of where they are, how many there are, how they are doing. They dry up so if you’re not out looking for them at the right time of year you might miss them and so they kind of fall through the cracks when it comes to our current wetland regulations.”

Lee says there are things that can be done to help scientists find our more about vernal pools and where to find them, or that people can get trained and help collect information and monitor the pools themselves.

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