Vernal Pools (Ephemeral Wetlands) with David Rosen

Hello and welcome to Golden State naturalist. I'm Michelle Fullner. And this episode we're gonna go on an adventure into some vernal pools. Now, if you're anything like me, you've likely spent most of your life having no idea what a vernal pool is. Maybe you're here and you don't know what they are right now. That's okay. I only found out about them in my California naturalist class. And I'm so grateful I did because they're so unique and amazing. And now I'm completely taken with them. But okay, what is a vernal pool. They're ephemeral or temporary wetlands that at least here in California go through three distinct phases, wet flower, and dry. There'll be a lot more on each of those phases later in the episode, but just know that this unique cycle of going through a wet phase where there's all these aquatic invertebrates, and then a flower phase where these beautiful flowers grow into the vernal pools and then a dry phase means that there's also a very unique sort of habitat and a lot of species of plants and invertebrate animals can only be found in vernal pools. So this blew my mind when I heard about it, especially since I've spent basically my entire life in California and had no idea these were even here. My guest, David Rosen, on the other hand, has been working in and around vernal pools for the last 19 years. He's so knowledgeable and also just so fun to hang out with. We met up during the wet phase in February. So in this episode, you're going to hear about a lot of the aquatic invertebrates you're also going to hear about some insects with no mouths, which common pest breathes through a tube and it's but when it's in its larval phase species that indicate good water quality, what kinds of birds and amphibians live in vernal pools? Why I'm so thankful that some of these invertebrates are tiny, and not human sized solitary bees, the underlying geology required to have vernal pools, the flowers that live there, and so much more. The best word that I can think of to describe my time out of the pools is enchanting. It was just a magical experience that really brought me back to my childhood just looking into this water and seeing what lived there. And I cannot wait to share that experience with you. I think you're gonna love it. But first, I wanted to remind you to make sure that you follow or subscribe to this podcast wherever you're listening. So if you're on Apple podcasts, that means clicking the little plus sign in the upper right hand corner, it should look like a check mark. If you already did that. I also wanted to let you know that you can follow me at Golden State naturalist on Instagram to see all kinds of cool pictures of my outings with naturalist and sometimes I'll post a call for questions so you can chime in to get all of your burning nature questions answered. So that's Golden State naturalist on Instagram. Finally, don't forget to share this podcast with any nature loving friends. So you might consider sharing with hikers, backpackers, campers, gardeners, people who like to go for walks the environmentally conscious, anyone who's naturally curious and the first person you would think to call if you found a wounded possum in your backyard. Hopefully it's the wildlife rescue. But if you call this person, they would tell you that so please share this podcast with any and all of those people. And without further ado, let's get our boots on and check out some vernal pools with biologist, wildlife photographer and naturalist with 40 years of experience in the field and also just all around great guy David Rosen on this episode of Golden State naturalist.

DR

Like just a vast open grassland. But when we step over that fence and venture out into it, you're going to be amazed because it is dotted with little vernal pools, each of which is unique, and each of which is teeming with little aquatic invertebrates right now,

when David and I met up, it was at the end of February, and it was a beautiful sunny day. And we hopped in his truck, and we drove out on a gravel road out in May their field. And as I looked out the window, I really couldn't see that much. It just looked like open grassland covered in these little mounds, that with the grass on top of them kind of gave the illusion of waves in the ocean, but I couldn't see any vernal pools from where we were on the road. The conversation you're hearing now is when we had gotten out of the truck, and we were standing on that gravel road, looking out at the grassland and how big is each vernal pool.

DR

It varies. Some vernal pools are really tiny, some are huge, and some can be just a few inches deep and others several feet deep. So it really kind of depends on the geology of the area. And it depends on that particular vernal pool

and can that impact What kind of life is found in the pool?

DR

Most definitely. Yeah, the deeper vernal pools sometimes have different critters living in them than the shallow vernal pools because the deeper vernal pools maintain the water in them longer during the season. So let's go further down to a vernal pool. Well, it's good to have this in there.

So we crossed over the fence off of the gravel road, and we're walking in the grass. And just out of nowhere as we get closer, I'm starting to see a couple of vernal pools. At this point, David had on his galoshes, and he got this white tray and he scooped some of the water from the vernal pool into it. Then he took a few careful steps out into the pool, and with a long neck did some practice to motions back and forth through the water. It's worth noting here that to be able to scoop in a vernal pool, you have to have a lot of paperwork done. So sacks blush, the organization that David works for, has both federal and state permits. So don't go try to scoop in a vernal pool because a lot of the animals in there are protected species. So we just got a big ol net full of the water from the vernal pool with we had a scoop of the water and then a net full of what was living in the water. And so I'm looking into this pan this broad white pan and I see some big guys in here see some little red guy so these little antennae look and things fooling around I see what looks like I'm sure they're not but they look like little slugs

DR

on the bottom that's a good description

and all the little crawly guys that are the lighter color I'm these are terrible descriptions, but but it's just teeming it is teeming with life.

DR

It truly is. And this is one of the things that makes the vernal pool a vernal pool is the unique aquatic critters that live in the vernal pools. Many of these only live in vernal pool habitat, nowhere else in the world but vernal pools, so we call them endemic creatures to the vernal pools,

David and I got to look at some of those vernal pool endemic creatures. And we also looked at a lot that are not endemic to vernal pools, but can be found in a lot of different types of bodies of water we recorded for over two hours, I would love to include everything from that, but it's just too long. So I had to pick and choose. I tried to pick my favorites, but it was really hard because it was all super fascinating. I'm gonna let David tell you about some of those creatures now. And the first couple you hear about can actually be found in a lot of different places. So what's the big guy here?

DR

So this, this large one right here, look through your magnifying glass. And if you look at the sides, do you see those beautiful, feathery gills? Those are gills. Those are gills and you'll see it quiver those skills in the water. And that's how they absorb oxygen from the water. That is a mayfly larva.

If you're hearing this and you're like, Okay, what is a mayfly? That's alright, they are in the same family as dragonflies and damselflies. And they do look sort of similar. They have those kind of glassy looking wings, and they're aquatic insects. They also have long tails. They're kind of cute. It's worth looking at a picture.

DR

And and so the may fly larvae. This actually it's really interesting. I've worked out here 19 years and have spent countless hours wandering around the vernal pools, collecting specimens. So of all the years, though, that I've been scooping out here this year, we have seen more of these beautiful little mayfly larvae than any other year really not not sure why. Conditions this year just tend to favor them, I guess, you know, when they become adults, they don't even have any mouthparts. They just need Yep, their sole purpose in their adult stage is to find a mate, reproduce and lay eggs, and then they die. So many of these may fly species only live 24 hours or less. I believe there's a species of may fly in Florida, that it hatches and they all hatch at the same time. It's a synchronous hatching, or I'm saying hatching. It's a synchronous metamorphose of the larvae into the adult winged form. They all leave the water at the same time. And it is a mating frenzy for these animals. And they Yeah, and some Florida species that I was referring to, I think dies within three or four hours.

Goodness, what a sight and that would be to see Yep.

Okay, so I didn't look into the specific Florida species of Mayfly. But I did look up mayflies in general and it looks like the male's might live for one or two days to the blank but the females usually only live for five minutes. They have five minutes to find a mate lay their eggs and die. And that's it. I found a page on pbs.org that even has a poem about this by a California poet Darren gaff blue. And here's what it says. The mayfly never sees the dawn but once before his end to think he's born upon the mourn, yet not see one again. So that's really sad, but also beautiful and a little bit like our lives. So remember the Mayfly. Okay, now at this point, David is going to back up a little bit and give some more context a little bit more information about vernal pools and the lifecycle of the creatures that live there. This part blew my mind more than almost anything he said all day,

DR

vernal pools, one of the things that makes them unique is they're ephemeral, they dry up every year, the majority of these animals that we're looking at right now, these little invertebrate critters, they actually need the pool to dry up for if the pool stayed wet year round, they wouldn't survive, oh my god, they wouldn't survive. And the reason is that these little aquatic invertebrates, when they reproduce, they lay cysts that are eggs, but with a very hard sis like coding such shell. And it's a fully formed embryo inside. And so they might be reproducing multiple generations during the time that the vernal pool is wet. But when the pool starts to dry down, it triggers changes in these invertebrates, and then they lay their cysts that will stay right on the soil at the bottom of the vernal pool sometimes for 100 years, or you see, yeah, yeah. And they just are resistant to the desiccation and heat of baking in the Sacramento summers,

which is incredible, because I've gone outside for five minutes in Sacramento in the summer. Exactly. And I promptly went back inside when it's

DR

110. Out here. Yeah, you know, with the air temperature, you figured the surface of the soil temperature is probably like 130 or more. And there are all these little microscopic cysts from these aquatic invertebrates that are just they're baking in the sun. But they need that to survive. If the pool fills up the following year. Some of them will hatch into embryo, some of them won't hatch. Yeah, exactly. What they're doing is they're hedging their bets. And so if all of them came out of their cysts at one time, and then the pool dried up too fast, they would. Yeah, exactly. And so from a species perspective, it's a wonderful strategy to stagger their emergence from the cysts. Wow. So some of the other ones that we see in here, do you see these little squiggly guys?

Oh, yeah. What's that guy?

DR

So this little one is kind of it looks like it's what about a centimeter long. Here's another one right here. squiggling through the water, they move by bending their bodies back and forth. With little larvae. That's exactly what they are. Yeah, that's the way they move. Yep. And this is kind of unusual to find mosquito larvae in our vernal pools here at their field, because you see all the critters that are in here, many of these little invertebrates eat detritus, they eat the bacteria, the decomposers that are feeding on the detritus, they eat the detritus itself. And so there's not a lot of dead matter in there giving off the decomposition gases that attract mosquitoes. Oh, so mosquitoes are attracted to stagnant kind of unifying wetland areas.

So should I feel bad about myself that mosquitoes like me more than other people

DR

know those are the adults. Yeah, that that must mean you're sweet.

I just smell good. Yeah, definitely not like Deacon decomposing. No,

DR

no, that's just that's just the larvae that that feed. That's good. But

does anyone else relate to this? If I go hang out on the patio with my husband for 20 minutes on some nice warm evening, when we come back inside, I'll have like 15 mosquito bites and he will have zero. It's insane.

DR

The mosquito larvae are fascinating animals. And you see how they squiggle in move, but then you'll always see them come back up to the surface and hang from their tail like this one. See how it's it's hanging from its butt? Yeah, right up at the surface. So they have a tube coming out from the top of their body just back by the hind end, and that is a breathing tube. It's like a snorkel. And so they hang out at the top of the water. You see these two are doing it right here. And they're getting oxygen and then when they get enough oxygen, they go back down into the water. like these over here. Now, if you were to look at it under the microscope, you would see these really pretty kind of golden brown brush like structures by their head, and they wave in the water. And what they're doing is they're creating a current, and they're filtering out little protozoa and little bits of algae and detritus, and things like that. And that's what they eat.

According to terminix.com mosquitoes only need as little as a bottle cap of water to be able to breed. I've also heard of them breeding in snail shells, Terminix also lists trash can lids, flowerpots, discarded cups, buckets, grill covers, and tires as some of the places where these guys breed. So make sure to check all of those areas in your backyard. It doesn't take very much water. But what about a creature that's a little bit more picky about the water that it lives in? So what are these really pale like flea looking guys like if like a fleas were really pale and they swam around?

DR

Well, you just nailed those. Those are WaterFire fleas. Now they're not related to terrestrial fleas,

somebody else thought they looked like fleas.

DR

Someone else thought so too. And so they're in the genus daphnia. And so you might sometimes hear people talking about daphnia being used for water quality experiments and things like that. They're very sensitive to water quality. And one thing that is in common with all these little creatures that you find inhabiting vernal pools as they all need clean water to

survive, so I must be doing well because these guys are thriving out here. Exactly.

DR

And so the vernal pools tend to have very clean water and the water although it looks like it's still it actually is flowing,

really, I was gonna ask I was like, because it seems like it would get stagnant.

DR

The water in these vernal pools it doesn't fill up because it rains and fills this shallow depression here, the way vernal pools fill up is from the bottom up, oh my gosh, because when it rains, there's a layer of hardpan impermeable hardpan a mixture of clay and dissolved minerals underneath the soil, it might be six inches deep, it might be a foot deep, might be a foot and a half deep, it depends on where you're standing. But when it rains, the water collects on top of this hard pan layer. And as it rains more, the water level rises. Eventually, the top of that perched water table becomes visible in these shallow depressions that we call vernal pools.

Wow. So this is kind of telling me if this is wrong, it's sort of like just a place where the water table is much higher, and then you've got like a grassland, correct. And then there's some depressions and all that all works together to make vernal pools

DR

kind of Yep. And and there have actually been some experiments done right here at the vernal pools that may 3 through University of California, I believe. And they were actually measuring they had a bunch of PVC pipe sticking down into the ground that had very sensitive instruments to measure water infiltration into the soil, water movement, subsurface, and they found that the water throughout this entire vernal pool grassland complex, that water that's perched on that hard pan layer is flowing, and so the entire perched water table is flowing. So, so the vernal pools get refreshed with fresh water.

And so it must filter through the soil filters, plants and everything that's going

DR

on, which helps clean the water if there are any impurities in it.

So don't judge me. But I Googled, can you drink vernal pool water and not so surprisingly, no one had an answer for this probably because no one wants to get sued. But also because everyone on the internet unanimously says you should never drink any natural water source without first filtering it and then purifying it either by boiling it or chemically purifying it, which should not be done with chemicals that you concoct yourself. But with specific tablets that are sold with the express purpose of making drinking water, there's a lot of little tiny things in the water that even if the water tastes really good, they could still really mess you up.

DR

But those water fleas actually are one of the more amazing critters that we have in the vernal pools because of their life cycles. So right now we're fairly early in the vernal pool season, and chances are nearly 100% of the water fleas that we see right in front of us here are females really? Yeah. And so when the vernal pools first fill up with water and the water flea cysts that were just sitting on the soil, for Lord knows how long when they hatch out all those are females. Oh my gosh, and they'll go through multiple generations. As parts energetically, wow, yeah, they just clone themselves.

Oxford languages defines parthenogenesis as reproduction from an ovum without fertilization, especially as a normal process in some invertebrates and lower plants.

DR

And so the female will produce a bunch of eggs each is an exact clone of the female water fleet. And then they carry those eggs around in their care EPIs in their shell. And if you look at water fleas, female water fleas that have these eggs in their shell, you can actually see them and when you look at them through a microscope, or you might be able to see it with the handlers and so you might find some that have some eggs in them now, they will continue to do this until the pool starts to dry down as I was mentioning before, and that triggers or monal changes in these animals that make them start producing Sunday eggs that will hatch into males.

Oh my goodness.

DR

And so the the sex determination in these eggs is actually controlled by environmental conditions

that reminds me of like sea turtles. Oh with sea turtles has to be a certain temperature for a clutch of eggs will be laid under the sand and then if it's a certain temperature, they'll be male and a certain temperature will be female. Okay, so this process and sea turtles is called temperature dependent sex determination or TSD. That's according to Ocean Science dot n oa.gov. Research shows that if turtles eggs incubate below at 1.86 degrees Fahrenheit, the turtle hatchlings will be male. If the eggs incubate above 87.8 degrees Fahrenheit however, the hatchlings will be female temperatures that fluctuate between the two extremes will produce a mix of male and female baby turtles, David said that it might be temperature or it might be photoperiod or maybe some other factors in the pools that trigger this sex determination in the water fleas there.

DR

As the pool starts to dry down, and it triggers these changes in these water fleas, they start producing haploid eggs as opposed to the deployed egg. So these haploid eggs, well, they start producing eggs that hatch into males, and then they produce these haploid eggs that need sexual reproduction to be able to develop it. Yeah, exactly. And so late in the season, you will often see these little water fleas with to brown cyst, like structures on their backs inside their therapists. Those are called a fibia. Each one's in a 1550s, plural. And these Excipient actually are the cysts that will survive the dry phase of the vernal pool each year and bake in the hot Sacramento summer. And then next time the conditions are right and the pool fills up with water, boom, you've got little water fleas that they're going to be females.

So and it all starts over again. Exactly.

DR

So it is just a truly remarkable process.

So do all of these critters in the vernal pools get along? Oh, not so much. David says there are some pretty intense predators in the vernal pools, some of these little aquatic invertebrates like the dragonfly and damselfly larvae and the aquatic beetle larvae prey upon things like the mosquito larvae, which is another one of the reasons you don't see too much mosquito larvae in the vernal pools and one of the predators that surprised me the most I'm just gonna let David tell you about it.

DR

Those are flatworms. flatworms. Yep. And we have three primary species of flatworms that we typically find out here. And most of what we've got in here right now, are these dark flatworms. Okay? The we do periodically scoop up some lighter brown flatworms, and one of my favorites are the bright fluorescent green. Oh goodness. They're about the same size as the ones you're looking at here. But they're bright green, and they actually have a species of algae that is living inside their bodies. Now the algae is photosynthetic, so it's making its own food and it shares some of that food with the flatworm. That's convenient. Yeah, I need that and then and then the flatworm provides shelter for the algae rather than just these free floating algal cells going through the vernal pool water they find a home inside this flatworm and so that's what's going on with the bright green flatworms. Now, all these flat worms can prey upon other critters in the vernal pool, but the flat worms have a mouth part in their stomach. and it's like a tool that projects out and they can insert it into their prey and slurp the insides of their. Yeah, it is horrifying. Just be very, very glad they're, they're not bigger than we are really glad. But yeah, so they suck the innards out of their prey item and then they bring their mouth part back in. But then after they digest stuff, it's not a continuous digestive system. It's a closed system. And so they poop out the same opening.

For a second someone's gets out.

DR

Exactly, exactly.

They'll low Unifor sense of security they look so squishy and harmless.

DR

Well, you know, I I shot a video one time of flatworms under a microscope. And, and I was watching it and it was all three of these species. So there were the black ones, the brown ones, the green ones, and they were all just flowing through the water. And it reminded me of lava lamps from the seven. Oh, for sure. And so I thought, this just really needs a Pink Floyd song in the background. And you do it. I did it for Bing Bing, a child of the 60s and 70s myself.

Have you gone into a cozy trance inspired by this talk of Pink Floyd, have you become comfortably numb? Well, I don't want you to become just another brick in the wall. So I'm gonna have to break up this party and tell you about a creature that's actually got a few things in common with the flat worms, but it takes things to a new level of sci fi horror. So get ready for this.

DR

Here's a tiny little aquatic beetle larva. Okay, what kind of small that is, but if you look at it with your magnifying glass, you might notice that it's got some serious pictures for its size. At the end its head. I don't know if he can see the pictures or not with the magnifying glass. But the aquatic beetle larvae, we can get much larger. I've seen them where they've been nearly three inches long. And these are huge pinchers Oh, my n. And it's something like from a science fiction movie because they will grab their prey and things even as largest tadpoles, these little aquatic invertebrates, the aquatic beetle larvae will eat vertebrate animals, if they can get them. Wow. And so they they will grab a hold of the tadpole, for example, with those big pictures. And through those pictures, they inject an enzyme and they keep holding on with the pictures. They're injecting this enzyme, the enzyme dissolves the insides of the tadpole. And then the remarkable thing is the aquatic beetle larva, it can reverse the pump mechanism on its pinchers, and it turns into straws, and it slurps out that tadpole soup.

Again, I'm really glad these aren't human size Exactly.

DR

Well, when when at splash when we have school groups coming out, we go and we scoop up samples from usually two or three different vernal pool sites. And we usually get some aquatic beetle larvae a little later in the season. Some of these are large, you know, pushing two to three inches long, big pictures that are tiny, right? And one day, one of my colleagues at splash and I were we're looking at these critters that we had scooped up and and I said, Hey, I'll give you a buck if you stick your finger in with that aquatic beetle larva. And she did. She stuck her pinky finger in there. And it nailed it. So they don't care what it is. They're big. You are exactly. They're opportunistic. And they they feel I mean, she felt a little pinch. It didn't hurt a lot. And you know, she pulled her finger out of the water like, but yeah, they're very opportunistic. And so they will go after whatever happens to be available and get the energy from it that they need. A little

bit later. We actually got to see one of these aquatic beetle larva in action, and it was insane. Oh,

DR

look, look at this. There's the aquatic beetle larva in it grabbed something else.

God something. Oh, yeah. And I borrow your magnifying glass real quick.

DR

Let's see what is it kit? Oh, man. Oh, look it it got made fly larva. It's kind of a tiny little may fly larva in its pictures. And so it's grabbed that may fly larva, it's injecting the enzymes through those pinchers. And it's dissolving the inside of the maze. So that's what it's just hanging on there for a minute. Exactly. And then it'll suck the dissolved insides out of that.

It reminds me of a dog that like you know, got a squirrel and then it shaking it.

DR

Yeah, exactly. Trying to get it in position. So Couldn't get those pictures in there because the aquatic beetle larvae don't have chewing mouthparts and so they have a liquefy yeah liquefy their prey and suck the juices.

I actually got a video of this moment and I'll post that on Instagram sometime within the next couple of days. But if this is all too horrifying for you, and you're wondering what else lives around the pools? Well the answer is a lot of things including specialized vernal pool plants, including some vernal pool endemic flowers, meaning that some of these flowers are only found in vernal pools. Some of them have a very special relationship with solitary bees. Now, we tend to think of bees as living in large colonies because many of us are most familiar with European honeybees. But as the name implies, those bees are actually native to Europe, not North America. Many of our native bees here are completely solitary, and were European honeybees are great generalists and will pollinate a wide variety of flowers, which is one of the reasons they're so useful in agriculture. Many native bees will have a highly specific specialized relationship, which is one species of flower. I'll let David tell you more about these bees.

DR

And there are several species of solitary bees out here in a few different generic and the solitary bees associate with the vernal pools but live more in the surrounding upland areas. So when we're talking about vernal pool conservation, we're not just talking about protecting the pool itself, we're talking about protecting an entire complex, an entire ecosystem that includes the wet vernal pool and the surrounding upland habitat because everything is connected in a vernal pool ecosystem and everything depends on everything else within the vernal pool ecosystem. So these little solitary bees live underground. They're not a communal sort of be like the honeybees. They don't have a big hive with you know, many individuals, they just have a little hole in the ground, and there's one beak living in there, hence the name. Bilbo Baggins, yep.

In a hole in the ground, there lived a hobbit not a nasty, dirty wet hole filled with the ends of worms and an Uzi smell nor yet a dry bear Sandy hole with nothing in it to sit down on or to eat. It was a hobbit hold, and that means comfort.

DR

And so they build this tunnel down into the soil, maybe eight to 10 maybe 12 inches.

Wow, that's far for a little bit it

DR

is and they'll have several little brood chambers coming off that main tunnel. So what they do is they just live underground and they get a signal, believe it or not when they're underground. They know when their species of vernal pool flower is blooming. Yeah, it's it's pretty remarkable.

So that in sync with it.

DR

They are and you know, conditions might be pretty good for down in GIA to be blooming for example,

down India is a really cute little vernal pool flower. It's purple. And it reminds me a little bit of a pansy.

DR

But maybe this year, at that pool, there's no down into the bees don't emerge. They can stay underground for two, three years. And then once their specific vernal pool flower blooms Foom. They come out they'll start visiting those flowers and they'll gather all the pollen. And within their little brood chambers in their underground tunnel. They make a little pollen bowl. And on each of those pollen bowls, they lay a single Lake. Wow. And when the larva little white, wormy looking thing hatches out, then the larva eats that pollen bowl, which is rich and protein. And it grows and grows and eventually metamorphosis into an adult winged solitary bee and repeats the cycle.

So it sounds like that's what the females are doing. Right? What are the males doing?

DR

That's a great question. The males are just going around looking for females.

They're having a great time. Yeah,

DR

exactly. So so they're living the bachelor lifestyle and you know, when when the vernal pool plants bloom, the males, you know, I think they still are pretty specific to the flowers that they visit, but they're not building the elaborate brood chambers and things like that. They're just going around looking for nectar so they can survive. I'm not sure what the lifespan of these little bees might be. But do you know that they can stay underground for two to three years?

Oh, and so there's several species out here like several

DR

species and they they sometimes have I have a specific species of vernal pool flower that they have evolved to coexist with Wow. And it's a mutualistic symbiosis because you know the bee benefits because it's gained the pollen so it can raise its young. And the flower benefits because in the process of the bee getting the pollen, the bee pollinate flowers, so they can go to see they

can the baby bees came back next year,

they'll be more flowers.

DR

So, you know, it's just a perfect, perfect example of that.

I'm so fascinated by the solitary bees, I would actually love to do a whole episode on native bees, so gonna keep my eyes out for somebody on that. But what kinds of vertebrate animals live in and around the pools. vernal pools

DR

are really important not just to the aquatic invertebrates, but to a host of other vertebrate animals that live in and around the surrounding grassland habitat. David

is super knowledgeable about birds. Here are a couple that we heard and saw when we were out there in February. The western meadowlark.

DR

western meadowlark, I think has one of the most beautiful bird songs in the United States. They're brilliant yellow on the front with a jet black V, on their breast. So if you see them from the front, they stand out really boldly. But if they fly away, and land out in the grasslands here, they blend in perfectly, they virtually disappear. And they nest on the ground.

We also saw a greater yellowlegs.

DR

Watch it feed, it's just going to be dipping back and forth into the water. And it's going to be pulling out all these little invertebrates that are so rich and protein.

There are also a couple of amphibians such as the spadefoot,

DR

which are a little tiny type of toad. Oh, and they're the cutest little things. If you if you look at a Western spayed foot, you'll notice it looks like Jabba the Hutt.

There are also Sierra and tree frogs in the pools and we actually got to see a couple of their tiny adorable tadpoles when we are out there. Now David and I could have spent all day looking at invertebrates in the pools but eventually it was time to move on to the interview. So we found a comfortable spot to sit on the grass beside one of the pools and I pulled out my questions. There's so much good stuff in this interview, including more about what makes a vernal pool a vernal pool science education that happens at Sacramento splash where David works, the amount of pools we have left where you can go to see one and what times of year it would be best to do that you're going to hear about all of that and more right after a short break

Okay, one last thing before the interview, and that is that there was a lot of audio I just couldn't fit into this episode, including David and I talking about the genetic diversity of animals in the pools how water boatman carry their own oxygen underwater in vertebrates called copepods and seed, shrimp and more. And I'm going to put all of that up on patreon.com/michelle Fullner, which is a way for listeners and supporters of the show to directly help this podcast get made by donating as little as $4 a month for that support. You get extra rewards like the audio extras that will be going up from this episode. Sometimes there are extra videos and behind the scenes updates on the show later this month. I'll also have my very first ask me anything AMA and folks who become oak level supporters. That's the highest level of support. By the end of April, we'll be getting a little thank you gift for me in May plus you get my eternal gratitude and the knowledge that you're making the show possible for me to create which enables all kinds of people to learn more about nature and why it's so important to protect it again, you can find all of that on patreon.com/michelle Fullner. That's Michelle with two L's Fullner is fu ll ner. Now let's get to the interview. How did you end up here? How did you end up interested in vernal pools and doing this work?

DR

That's that's a great question. Gosh, I I'd say it started when I was 12. And it was thanks to Sara Lee coffee cake. What? So butter pecan coffee cake to be precise. And they used to come in these little round tins, aluminum tins. And I decided one day when I was 12 I asked my folks Hey, can I make a bird feeder out of this and hang it up in our backyard? And so we did we started getting a bunch of birds I fell in love with birds decided I don't know what I want to do if I ever grow up, which I don't think I have. But it's going to involve nature. It's going to involve wildlife and sharing cool things with other people. And so I've worked for over 40 years as a naturalist with various organizations and agencies and so forth. And I pursued my own photography, business shoe nature and wildlife photos for publications. And so I got a call one day from a woman named Eva Butler. And she was the founder of Sacramento splash back in the late 90s, and 2000. And she just recently retired move back to Maine where she has a home and Eva was contracting me as a photographer to photograph plants and animals, of the vernal pool ecosystems here, it made her feel this was 19 years ago, when I made first contact with Eva. So Eva is taking me around the vernal pools and pointing out all this cool stuff. And she is so passionate about vernal pools, and so passionate about protecting it. And as we were walking, I just happen to share more about my background, and you know, my background in environmental education. And she said, wow, we're looking for guides here at splash, would you be interested in guiding for us at splash, and so I took maybe all of about 30 seconds, and I told her, You seem nice enough. Sure What the hell. And so that was how my relationship with splash and vernal pool ecosystem started. And I learned so much from Eva. And, and you can't get a more passionate individual when it comes to vernal pools than even up there. And so I just fell in love with vernal pools as well. And just from what you've seen today, in the short time we've been out here, how could you not followed with vernal pools?

I'm hooked.

I'll be back. Yeah, very cool.

I actually already have gone back to see the flower phase, which I'll tell you a little bit more about later. But I'd also love to go back again during the dry phase. And then again next year during the wet phase, I have a feeling there will just always be something interesting to see at the vernal pools. All right. So I think we need to back up a little bit to and say, What do you think what is a vernal pool?

DR

Great question. Yeah, vernal pool is an ephemeral wetland here in California goes through three distinct phases. There's a wet face, like what we're looking at right now. We're sitting here by the edge of this beautiful vernal pool, and it's just full of water. Okay, it's teeming with the aquatic invertebrates that we've been looking at. And many of those are threatened and endangered species. Now, eventually, this pool is going to start drying up. And when it does, there's a unique set of plants that many of which only associate with vernal pools, their vernal pool endemic species only found around vernal pools and you start seeing rings of these flowers around the vernal pool as the vernal pool dries up. Eventually, those flowers as the water goes away from the vernal pool through evaporation primarily, the flowers will cover the bottom of the vernal pool, and so many different species of flowers during that flower phase.

Okay, so as I mentioned a minute ago, I did just recently go back out to the vernal pools, and I did this during the flower phase, probably about a week ago now. And it was amazing, very similar in the way that you walk out onto the grassland and it just looks like a grassland, but then you keep walking. And now instead of finding a pool full of water, you find this basin of flowers, and it's just this gold and purple and white, and it's just gorgeous. And so now David is about to tell you the names of some of those flowers, and I want to challenge you to just Google at least one of them because there are some very cool looking flowers out there. You've got

DR

vernal pool gold fields that coat the bottom of the pool, you've got white never Reshef that looks like snow has fallen on the vernal pool, you've got around the edges, you've got down NGF we have three different species of down ninja. Here. We have vernal pool, checker, bloom and meadow foam and vernal pool monkey flower. And, you know, that's just I mean, there are dozens and dozens of really amazing species of plants. So we've talked about two phases, the wet phase and the flower phase. Now, eventually these flowers will have all been pollinated. They've all gone to seed, they've disperse their seeds and the pool is totally dry. And that usually happens here at Mater field by late April. The pools usually are pretty dry by mid May things are pretty hot. and crispy out here.

So the flowers are pretty much done by that

DR

the flowers are done by that point, there might still be a few species of flowers that grow in upland areas blooming in mid to late May, but you know, not too many. And so we've got those three distinct phases that the vernal pools go through. So that's something that makes the vernal pools unique, and the little vernal pool invertebrates that have deposited their cysts. Those cysts need that dry phase in order to persist. And they need to bake in the hot Sacramento sun. And during the summer months, and if the pool were to stay wet year round, you'd see an entirely different array of plants and animals. vernal pool animals, the little invertebrates and vernal pool plants have evolved in conjunction with the wet phase flower phase dry phase cycle of the vernal pools here.

Remember from earlier David said that part of what makes a vernal pool a vernal pool is that underlying geology, it has to have that hardpan layer to bring the water table up really high. It's called a perched water table. And part of what that does is create a really special habitat for very specific plants.

DR

And then also, vernal pools here in California. I mean, they're an endangered habitat. There used to be so many vernal pools throughout the Central Valley of California, and now that we've lost probably 90 to 95% of the historic vernal pools that used to be here. So it's a rare habitat subsequently, many of the plants and animals associated with vernal pools have become threatened or endangered as well, because they've lost their habitat. And that habitat loss is primarily due to agricultural development and urban development and things like that.

So where can people still find vernal pools? Are they mostly in this area or that can you find them down in Southern California or the southern reaches of the Central Valley too?

DR

You can you can find vernal pools in one of the largest contiguous blocks of vernal pool habitat is just little northeast of Merced down in the San Joaquin Valley, but there are vernal pools down in the San Joaquin Valley. There are vernal pools in the Sacramento region. And as you go north in the Sacramento Valley there vernal pools up around to Hamer County, Glen County, you know, possibly even up to Shasta County.

Wow. So I was curious about how far south you could go in California and still find vernal pools and I found a page by the San Diego Zoo wildlife Alliance saying that there are vernal pools in San Diego and the site says while vernal pools once covered roughly 200 square miles in San Diego County. It's estimated that 97% have been destroyed due to land development for housing, agriculture and grazing, vernal pools that still remain are threatened by the spread of invasive grasses off road vehicles and urbanization. So there aren't that many left and they are threatened. But there are some down there in San Diego. They even have a unique plant species in the San Diego pools called misalignment. I'll put a link to this page in the show notes so you can learn more about it. So you talked about a little bit I was going to ask you how they're formed. I guess he didn't say how they were formed. I mean, it's that hard pan underneath, but like, where does that come from? Why is that they're here, and maybe not in some other grassland areas?

DR

Beats me.

Are you ready for all the geology puns you're about to hear? I don't know if you're ready. Here they go.

DR

I'm honestly I'm pretty igneous when it comes. I've always just taken it for granted. I'd come up with a few more geology plans if are a little bolder. So at any rate, yeah, the hard pan I actually am not positive how it formed. But these are ancient riverbeds in here and so the riverbeds flowing 150,000 years ago or or more day we're carrying a lot of silt and eroded material from the Sierra Nevada range. And a lot of that was deposited a lot of that was probably clay particles and things like that in the silt. And so the hardpan is predominantly clay and and cobbles and things like that. So the cobbles, probably leftover from the old riverbeds, the clay material that was deposited from those ancient riverbeds as eroded down from the Sierra Nevada. Fascinating.

Funny story. Weeks after recording this interview, I found out that David Rosen is actually friends with Nate Manley the geologists from my first step I sewed and they know each other because Nate used to be on the board at SAC splash where David works. So of course, I reached out to Nate to try to answer this question and I asked him why there was that shallow hardpan layer there under the vernal pools and he said, it probably has to do with the distribution of sedimentary materials sands versus salts versus clays when they were first laid down. Then there's the effects of weathering, older soils will develop a cemented horizon created by dissolution and disintegration of materials near the surface and re deposition of those materials lower down in the soil profile, he said, we also have to consider bioturbation the disruption and redistribution of near surface soils by critters like pocket gophers. I don't know if you remember from the beginning of the episode, but I mentioned that there are these little tiny mounds scattered all over the vernal pool grasslands. And turns out that those little mounds are actually created by gophers who are moving the dirt around and the mounds fall roughly along the territorial lines of the gophers. So those are called Mima mounds and nated, that that's potentially related to the formation of the pools too. So the next one I wanted to ask you about is, you mentioned that three phases, right, we've got the wet, the flower and the dry, right? What's your favorite?

DR

Oh, boy, that is so hard. I would say I'm fascinated by the aquatic invertebrates. During the wet phase, I just loved them. And, and you can just as we were doing before, you can sit for hours, just watch them swimming around in the pan that you've collected. And it's so wonderful to see the students faces when we have school field trips coming out to splash. And see the students just light up when they look through a dissecting scope and see a live clam trip. And that was the critter that they became the class expert on when they were studying the splash curriculum in their classroom or you know, when they see those vicious pinchers on on an aquatic beetle larva, up close and personal. And when they see the little fairy shrimp through a microscope, because part of the splash program, when the students are doing the splash lessons in class before they come out on their field trip, they actually get the opportunity to grow fairy shrimp in their class that we send them fairy shrimp cysts, and it don't worry, it's not from any endangered species or anything like that. And so the students put what just looks like dust in a glass enamel or glass pan and fill it up with some spring water. And, you know, keep it away from direct sunlight, where it's gonna get too hot, and boom, they have little fairy shrimp, and that is splash lessons, get them doing population surveys, you know, the rate of emergence of the fairy shrimp from their cysts, and they grasp things out and, and so it's, you know, interdisciplinary, yeah, they are working on math skills with our curriculum, they're working on science stuff with our curriculum, they have art opportunities with our curriculum. And and it's just, it's a wonderful opportunity for many of these students to witness things that they've never had a chance to see. And when they come out on their field trips, so many of these kids have never been out in nature. They might be from Title One schools, they might live in an urban area where they're surrounded by buildings and paid and the transportation to get out here as in transportation is a challenge. And, and so it's an incredible opportunity to provide a positive, exciting, first experience in nature for these students. And that's what I think Splash is all about, you know, the cool information about the vernal pools is great. But what we are primarily out here to do is to make connections between nature and these students and, and get the students excited about being in nature, and get them feeling comfortable with being in nature, and get them interested in science so that they might want to pursue it later in life.

That's fantastic. We get people from a lot of backgrounds to be involved in science and a lot of different perspectives. That's great. Yep.

DR

And those nature connections are key to at all. And that's the true magic of splash.

I love this hands on approach to getting kids involved in nature and science. And what if we had don't want to come out and see the pools too. Well, if you live anywhere close to Sacramento, you can sign up for a public tour with SEC splash. The last remaining date for a tour this year is April 24. And there are still a few spaces available in the afternoon session, David says to add to the waitlist, if that fills up, and there's still a chance that you can get it, you can sign up for the tours on sac splash.org, which I'll link in the show notes. And if you can't get it on a tour, is it acceptable to walk around or do you just is it you just recommend that people stay away so they're not walking on the ecosystem or

DR

that's that's kind of a gray area. Okay, right now. The land manager out here center for natural Lands Management, who's managing the 1400 acre vernal pool preserve here at made their field for Sacramento County. They would prefer to not have a lot of people wondered, I personally think there's there's a fine line between too many people walking around and nobody walking around. We definitely don't want to impact the vernal pools negatively. But there are some real advantages to having people come out here. That was the whole reason the splash program started. The only reason the 1400 acres of this vernal pool preserve are still here is because Eva Butler and Sacramento splash. got people coming out here built a community of vernal pool advocates, who when the time came, stood up to development interests that wanted to put a sports complex in over the vernal pools, soccer fields, baseball fields and things like that. And that would have done away with some of the premier vernal pool habitat and species in the whole Sacramento region. Getting people out here and learning about vernal pools as long as they are respectful to the habitat and its inhabitants. It's it's really, I think, very critical to the survival of vernal pools, people are only going to want to protect what they know about and people only know about what they are taught. And so when people come out here and experience it firsthand. You've got a vernal pool advocate for life.

Yeah, absolutely. So try to get on a tour. Yep, do your best to get in one of those add to a waitlist. If you can't and you really want to come see it. Just be very respectful. Don't be picking flowers. Don't be walking in the vernal pools don't scoop out any invertebrates because you need a special permit for all of that. So just be super respectful and cautious around the vernal pools

DR

Exactly. Okay. And it's currently not posted. No trespassing. So you know, someone might come and ask what you're doing and visit with you for a little bit if it's a Sacramento County Park Ranger or you know, one of the managers from Center for natural lands management, but you know, technically right now it's not posted. So

okay, mostly be respectful. That's the most important Exactly. So that's what you need to know about visiting vernal pools in the Sacramento area at me their field, but I would imagine that it's similar in other places. So just make sure that wherever you live, if you want to visit vernal pools to look into any local organizations that might be able to help with that. And if you visit on your own, make sure that you're not trespassing and make sure to be respectful there. I wanted to back up to a question earlier, I didn't ask my follow up, which is we talked a little bit about where in California you can find vernal pools. Are there places outside of California with vernal pools, are they similar? Are they different?

DR

There are vernal pools elsewhere and and there are vernal pools in the eastern United States too, but they are very different. Most of the vernal pools out in the eastern states, you know from you know the Mid Atlantic region north up into name you find what are referred to as vernal pools and they do fill up with water during the winter rains, they the water stays in those vernal pools longer I believe that some of them might dry up but not all of them and they typically are found in wooded areas.

Yeah, this is the only vernal pool we've seen that's got trees near it at all. You know they're very widely spaced, we're not in the woods.

DR

We're not in the woods by any means. And but the vernal pools out east typically are in a more wooded area, but there are some similar critters. There are some fairy shrimp that live in those vernal pools. There are various salamander species that live in those vernal pools. One of the main characteristics of any vernal pool is there are no fish, and of course the vernal pools out here are dry up every year. Most of the vernal pools back east dry up every year, and fish could not survive. And so the animals that live in the vernal pool have have evolved different strategies to survive that dry phase. You know, the salamanders, they'll go through their aquatic larval stage metamorphose into the terrestrial stage. And then they'll go and find a nice log to crawl under. And, you know, survive hot, drier periods, stain moist, maybe go down out here. Some of the amphibians like this yarn, treefrogs, the Western spade foots, you know, they bury themselves in the soil, the spade foots actually dig their own burrow actually named Exactly, they have little, little black hard shovel like structures on their hind leg and they burrow backwards into the soil and cover themselves up as they go. So they might be, you know, six inches down in the soil, and they coat themselves with a layer of mucus, and they stay there for 10 months. Oh my goodness, until a month until precipitation comes and it kind of wakes them up. And if it seems like enough, they've come out and they go to the vernal pool and they they mate, and then rinse and repeat. Yeah,

I'm not gonna lie it there have been moments that I've wished I could do this during the Sacramento summer. So So here in you know this where it gets super hot in the summer in Sacramento? Is the dry phase the longest phase? It is okay. Definitely. And in the eastern ones that you're talking about with the wet phase be longer, probably okay. Yep. Here though, in the dry phase. Is there really anything to say during the dry phase? Or is that it can

DR

be really fun coming out. You know, my suggestion, given the temperatures we get here, come out in the morning.

Yeah, bring water coming. Yeah.

DR

But if you walk out into a dry vernal pool, you're not going to necessarily be negatively impacted habitat because it's going to be really dry, hard packed soil. Okay, but you can sometimes look very closely and find the exoskeletons of some of the vernal pool and vertebrates that were living there during the winter. So this pool in particular has California clam shrimp in it, and it has dragonfly larvae in it, and it has aquatic snails in it. And you go out into the deepest part of the vernal pool and of course, during the dry phase, it would be totally dry. But as the water receded in the vernal pool, all those little critters converged into the last remaining wet areas. And then when that dried up, they died. And they left their exoskeletons concentrated in a rather small area. And it's really kind of fun to go through and say, Oh, look, this is the caribou this from a vernal pool tadpole trick that was in here.

Are they all sunbleached at this point, or are they have colors?

DR

Some of them still have colors, some of them are brownish, you know, but you can find the Karapiro you know exoskeleton from vernal pool tadpole shrimp, you can find, you know, dragonfly larvae, skeletons, clams, shrimp shells, you can find aquatic snail shells. And, and so there are things to see out here. During during the warmer months during the dry phase, you just have to know where to look. Exactly. And some of the birds that nest out here are still nest in it that okay, so you might still see some meadowlarks, you know, sitting around singing and proclaiming their territory, and defending their territory and male Redwing blackbirds defending their territory and the nests of the females in certain areas. Yeah, so there still are cool things to see during those months. Nice.

I just love the idea that you can go at different times of the year and see completely different things and have it always be new. vernal pools are such special places. And I love the work that they're doing. It's x flash to try to preserve those areas and teach others about them, especially teaching kids, which is why I asked my next question. How can people support what you're doing here? How can you know we make sure that these pools get preserved into the future

DR

be advocates for open space protection. We have lost so much open space in the Sacramento area. I live in Woodland personally and and you know when I first moved to Woodland, and I would drive back and forth to Sacramento splash between woodland and Sacramento, all you had was the airport. Now we have the whole Natomas North Natoma style. And then there are even more warehouses and businesses being established just south of the airport. And we're losing all that open space. And there were vernal pools in that open space And so, in general, being an advocate for open space protection is one of the best ways that you can protect vernal pools. If you want to support the education of kids about vernal pools, then go to splashes website, and we've got a very conspicuous button.

Donate now go for it. Everyone go

DR

exactly make a donation. And so you can certainly make a donation to splash.

David said that if you do want to make a donation, it will have the best greatest impact if you do it on the big day of giving, which is on May 5, because they're always matching donations. On that day, David says that there have been close to 70,000 graduates from splashes investigating vernal pools program to date and the program is still going strong. If you're listening and you're one of those 70,000 graduates, I would love to hear from you. So tag me in a post on Instagram about which vernal pool critter you became the clasp expert on. I would love to hear about that. David also said that splash served about 100 classes per year with this program. And it's looking into expanding potentially using other vernal pools in the area. And lots of other educational programs are going on through splash to all of them run by a small and very efficient staff. So if you do choose to make a donation, just know it's going to a really good cause. Well, with that in mind, I only have one question left for you. Which is what about your workout here? Still just takes your breath away?

DR

Sorry, get kind of choked up. When I think about this seen the kids faces? Yeah. When? How often do you see a fourth grade boy jumping up and down with sheer delight, because he just got to see his vernal pool flower that he became the class expert on. You know, we see that on a daily basis. And it just it warms our hearts.

3

It truly does. That's incredible. Yep. Such a worthwhile

DR

and so being able to do exactly what I'm doing right now sharing the wonders of this area and this habitat with other people. Yeah,

that's fantastic. And that will stick with those kids for the rest of their lives.

It does. That is so cool. Well, thank you so much. I know you guys are insanely busy. You took so much time Oh, to venture out with me. And I really appreciate it.

DR

My pleasure, Michelle, it was it was truly a pleasure. How often, you know, can people say they get to go out and just sit by room. Not often talk with someone as nice as your five first time. So thank you so much for the opportunity.

I love David's passion for both vernal pools, and instilling a love of nature in the next generation. It makes me feel so good to know how many kids over the years have been impacted by this program. Before I sign off, I just want to say thanks to a few people, including Nate Manley for consulting on geology for this episode to my amazing Patrons for making this show possible to the very cool community of nature enthusiast that's really starting to blossom around the show on Instagram, your comments and questions showing me that this work matters and is actually getting out there to people. So thank you for that. Thank you to everyone who has rated or reviewed this podcast, it really helps keep it up in the charts, which helps other people find it. So please do that. If you haven't yet it it really means a lot to me. And I read them all and I love them. And thank you to my amazing best friend and life partners, Dan Brown for doing more than your fair share of household stuff. So I can make this podcast and for being my sounding board for everything to do with everything but also for this podcast. The last little tidbit in each episode is that I tell you something interesting for my week. And this week. It's something embarrassing. So this shirt and it's got this this native Poppy I think it's pronounced Mata li ha I'm not sure if I'm saying that right. But anyways, it's got this Poppy on it and I love this shirt. And I wore it last week when Stan and I went out to the vernal pools to check out the flower phase and I was so proud of the shirt. And I was just ready for someone to see me and give me a compliment on it. So we're walking out and this big group of people is walking away from the vernal pools and I'm like just ready for someone to say something nice about my shirt. And then we're walking by this guy and he kind of goes past me and right after he goes past me, he goes, I love your shirt. And before I can even turn around I go thank you turn around. And I realize he's saying that to my husband who's right behind me and has this cool skeleton shirt on and he was really not talking to me at all. So that was both disappointing and very embarrassing, but I was happy first And that he got a compliment on his very cool shirt. So anyway, the teacher of this class that was out there did stop and compliment me on my shirt. So thank you. That was Rene. Thank you for that. You. You. You saved me on that one. There was a compliment for my shirt out there. So thank you. Okay. Wow, this episode got really long. Thank you for listening. You're the best. I love you. And I'll see you next time on another episode of Golden State naturalist bye

the song you just heard is called I don't know buy grapes and you can find a link to that song as well as to the Creative Commons license in the show notes. Go by