It’s the time of year when storms begin rolling in again across Northern California, bringing much-needed water to the dry landscape.
And that precipitation is causing life to rebloom again in the region’s vernal pools, small temporary wetlands caused by rainwater filling up depressions in the ground.
These pools are scattered across California, though many have been lost to time. Throughout the winter and spring these wetlands are teeming with unique plant and animal species, some of which can be found nowhere else.
But that beauty and diversity is fleeting as the weather dries out and the pools evaporate, ready to return with the next rains.
Near Mather Field in Sacramento, the public has a chance to see some of these vernal pools, which date back between 50,000 and 200,000 years.
David Rosen is the Director of Educational Programming and Lead Naturalist with the nonprofit Sacramento Splash.
He recently spoke with Insight Host Vicki Gonzalez about the uniqueness of the vernal pool habitat, and how his organization is helping to bring that science to the greater public.
This interview has been edited for length and clarity.
Interview highlights
How did you become so interested and passionate about vernal pools?
Personally, I became passionate about birds when I was 12 years old and just dove in head first. Then that just expanded to learning about all things nature. I’ve worked as a naturalist and environmental educator for over 40 years now, and the last 22 of which have been with Splash…
And the last 22 of which have been with Splash, which is just the most phenomenal organization, small but mighty. Last year alone, we connected over 20,000 students with nature and science.
What is Sacramento Splash? How do you teach people about vernal pools?
Well, as you might suspect by the name, we focus a lot on water… water quality issues throughout Sacramento. We try to encourage students to adopt different practices around their neighborhoods to prevent pollution from getting into stormwater runoff and going down storm drains, which jeopardizes life in our local waterways… but also jeopardizes our drinking water.
Our Splash Education Center is located at Mather Field. It’s surrounded by a nearly 1,400-acre vernal pool preserve called the Illa M. Collin Conservation Preserve. Sacramento Splash has been using that preserve as an outdoor classroom for 26 years now.
So what is a vernal pool exactly? How do they develop?
They develop over tens of thousands of years. It’s a temporary wetland habitat that fills with rain… that’s how it all starts. The rain saturates the soil and you get this perched water table on top of a layer of hardpan underneath the vernal pool grassland habitat. And then when the pools fill with water, they explode with life. They are teeming with thousands and thousands of little aquatic invertebrates, of dozens of species. Many of these are threatened and endangered species because vernal pools themselves are an endangered habitat. We have lost well over 90% of the historic vernal pools that used to occur here in California.
Invertebrate exoskeletons seen in a vernal pool during the dry phase.Courtesy of David Rosen
You have three distinct phases. The wet phase where it’s teeming with the aquatic invertebrates, and then as the pool starts to dry down it enters what we call the “flower phase.” The pools become ringed with beautiful vernal pool flowers. And as the pool continues to dry up, the entire pool gets coated with this incredible kaleidoscope of colors. Then, as everyone knows here in the Sacramento Valley during the summer it’s 180 degrees and everything gets hot and crunchy and crispy out there, and we get into the dry phase.
But the next time it rains there are little cysts, little eggs that can last through the dry phase and can actually last for dozens and dozens of years. So when the pool fills up again, boom, they pop open and it’s filled with little aquatic invertebrates again.
Are there any special guidelines or maybe rules like do’s and don’ts about visiting a Vernal Pool and interacting with it?
There are. Because vernal pools have become such an endangered habitat here in California, many of the plants and animals that are endemic to vernal pools… they’re found nowhere else in the world except vernal pool habitat. With the loss of so much of that habitat, many of these plants and animals have become threatened and endangered species as well. You can’t just go up to a vernal pool, start scooping up critters and checking them out because it could be disturbing a federally-threatened or endangered species or a state-listed species.
In order to do what we do at Splash, we have special permits through the federal government, through the US Fish and Wildlife Service, through California State Department of Fish and Wildlife. [The permits] allow us to legally go out and scoop up aquatic invertebrates, survey what is living in the vernal pools out at Mather Field, and to be able to use some of those creatures for educational purposes.
What is it like to share your work with others, and maybe teach them something about these pools for the first time?
It’s magic, it truly is. When you can get a fourth-grade boy out on a school field trip jumping up and down because he found his vernal pool flower that he became the class expert on, that’s the magic of Splash right there. We’re building future scientists, we’re growing future environmental stewards.
Students scoop up samples in a vernal pool near Mather Field.Courtesy of David Rosen
We have kids coming in, and we put some of these aquatic invertebrates under microscopes for the students to identify, their eyes just go wide open. Each student becomes the expert on a vernal pool plant and animal. And so when they come out on their field trip, they’re thrilled to death to be able to see the creature that they became the class expert on. Even if it’s a tiny little water flea, the size of a period at the end of a sentence in a book… they discovered it or they learned about it.
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