(Dial tone of phone) ♪ ♪ (Uplifting dramatic music) ♪ ♪ [NARRATOR] Beautiful nature: a seemingly endless array of animals and plants that share our planet, with each species unique.

An extraordinary diversity of life expressed in huge differences in appearance and behavior.

Yet, what's common to all is that each has a home, in an ecosystem that not only supports them but has, over eons, shaped their uniqueness.

Documentaries introduce us to these ecosystems, providing a context for the exotic animals and plants that call them home.

Often these habitats are vast, expansive, found in faraway places or remote locations which most of us will never visit.

Yet, there is an ecosystem right nearby that is equally diverse.

Small and often overlooked, it supports a group of unique animals and plants that have adapted to living only there.

Some are quite rare and even endangered.

Exploring their world begins with understanding their home.

(Reflective guitar music) [NARRATOR] Coastal plain ponds, ephemeral pools, even whale wallows-- Vernal pools are called by as many different names as the many places where they are found.

[A. SCOTT ANDRES] The vernal pools form in a geological unit that we call Carolina bays or Delmarva bays.

The Carolina bays are formed in holes.

These features exist all over the state of Delaware and you can find them in adjacent New Jersey, Maryland, and even into Virginia.

[NARRATOR] No matter where they're located, vernal pools all function in a similar manner that creates a unique and unusual natural habitat.

[MICHAEL S. HAYSLETT] Well, this is a vernal pond, a vernal pool, here in the Allegheny highlands of western Virginia.

We're on a ridge top, at approximately 12, 1400 foot elevation above sea level, and on the tops of our middle ridges we often find these sinkhole basins that contain vernal pools.

Not too many feet below us is limestone; the underlying limestone having dissolved, and the cap of rock above it slumped into that void over, over many, many, millennia, and those create the liner that can hold and perch water on the surface of this depression.

That's what creates a seasonal wetland or vernal pond in the mountains.

[NARRATOR] Large or small, these temporary pools only appear in depressions where the surrounding soil collects and holds rainwater near the ground surface.

In the Virginia mountains, ancient impervious rock under that soil blocks that water from draining deeper underground.

[STEVEN DAVID JOHNSON] So, this is a solid bottom pool that one of my students in Conservation Photography actually found, just a real beauty, perfectly round, very clear water, but sometimes it will dry out in the middle of the summer.

But I was surprised today, we came up, and it's October, and I guess we have had a fair bit of rain, so there's several inches of water in here.

We saw some frogs jump, so life is happening in the fall right here on the border of Virginia and West Virginia.

[NARRATOR] Large or small, all vernal pools share a common underlying hydrologic feature.

[ANDRES] The water table is fairly close to land surface, so as the water table goes up and down with seasons and weather patterns, there are times of the year when these features fill up both with run-off that's coming over the land surface, and as the water table rises, it can rise up from within the basin itself and flood it from below.

[NARRATOR] Which is how the seasonal pools that dot the Delmarva peninsula fill each year.

But unlike the mountain basins, these depressions, commonly known as Delmarva bays, were formed by vastly different geologic forces.

[JIM WHITE] These Delmarva bays are very old.

In fact, most of them are in the range of 10,000 years old.

They were formed back when this area was very different, it was the end of the last ice age, and this area was very cold and relatively open habitat, and we believe these bays were formed during that time period when water would kind of fill in depressions, and wind would actually blow the sand...in the pond in a circular fashion.

It would scour out the bottom of these bays.

Another unique thing about the Delmarva bays is they're not filled by rainwater.

There's no inlets or outlets of these ponds.

They're just a bowl basically, how they fill is the ground water rises, the ground water rises up into the pond and forms over a clay lens.

[NARRATOR] Because they dry out, these ancient pools cannot support fish.

Yet, thousands of years of predictable flooding and drying, combined with the lack of year-round aquatic predators, have meant that many unusual species could evolve and come to rely on these unique seasonal wetlands.

[JIM WHITE] So, these ponds are incredibly biologically diverse, and particularly diverse in amphibians.

Some of our rarest species occur only in these Delmarva bays, species like the Eastern Tiger salamander, the Barking Tree frog.

They're species that you don't find anywhere else except in this type of wetland.

(Birds chirping) [NARRATOR] Autumn: the leaves and weather change as the surrounding forest's annual season of growth winds down.

But for the species relying on these unique ecosystems, the annual cycle of life is just beginning.

[HAYSLETT] For an amphibian biologist like myself, fall is the start of the calendar year for a vernal pool because that's when Marbled salamanders emigrate in under the cloak of darkness and rain, and mate, and then the females will lay their eggs under the leaf litter or a log in the dry basin where the moist soil and leaves can protect those eggs.

Here is a female, an adult female Marbled salamander sitting on her nest, on her clutch of eggs.

They're little individual eggs not contained in jelly, almost like tiny ping pong balls, and she is attending this clutch of eggs that she has deposited in this moist depression under the log.

This is one of the few examples of a small amphibian providing maternal care for her young.

[HAYSLETT] These tiny individual eggs in a clutch with the mom curled around them for protection... And then she will stay with them and protect that nest until the pool inundates.

That terrestrial breeding strategy is unique among the amphibians that use a vernal pool.

All of the salamanders, and certainly wood frogs, encase their eggs in jelly because they're aquatic breeders.

The Marbled salamander comes to the vernal pool well ahead of all of the other species, so that its young can hatch, and its larvae can develop and get an edge on all of the others that will enter this pool in late winter.

[STEVEN DAVID JOHNSON] So, we're in Virginia at the base of Shenandoah mountain, and this is one of my favorite vernal pools.

It's really small, and seems to be fed by the seeps and run-off coming off the slope off here, but even though it's very small, it's actually very productive, when I come here in the spring, it will just be full of Spotted salamander eggs and Wood frog eggs that are absolutely luminous in the sunlight.

And then for months, I can watch those interactions.

There's just so much life that's hidden in here.

(Soft sound of snow falling) [NARRATOR] With the arrival of winter, the plant life in the surrounding forest goes dormant, and the water table rises within the pools.

The amphibians that rely on them are uniquely adapted to the cold, and often arrive when snow is still on the ground.

[WHITE] The ice is about an inch thick, a little less actually here, maybe half an inch, a little thicker out there.

I'm not picking up anything right in here; we're still in the shallows.

This pond, when we go out further, it will get much, much deeper, in fact, way too deep for these boots that I'm wearing at the moment.

So, we're just working here.

I don't see much in here.

A lot of the invertebrates and the salamander larvae are probably out in the deeper water.

They don't want to be caught in here in the shallows because the oxygen level can drop in these shallow areas in the water.

So, they want to be out in the deeper water where there's-- whoop...there's ahh...got a nice big tadpole, this is...looks like, a Green frog tadpole.

Yup.

He'll metamorphose next spring, he feeds on algae, so he doesn't have to chase anything, so he can feed very slowly.

I'm sure he's moving slowly in these temperatures.

Let him go.

(Sound of leaves rustling under foot) [NARRATOR] Along with tadpoles, Tiger salamanders have arrived.

The largest salamander using the pools, tigers are an endangered species in Delaware, and are closely monitored.

They've left their burrows in the surrounding woodlands, and have come down to the pools to mate.

[NATE NAZDROWICZ] So, here it looks like we have a female Tiger salamander that's just resting on the bottom.

Uh, she was here in the pool before nightfall, so she's hiding under that leaf uh, just to camouflage during the daytime because the water that she is in is not very deep, it's only about 15 centimeters.

Uh, but once night falls, uh, she'll become active, uh, Tiger salamanders are nocturnal, she'll become active and begin looking for a mate in the pool.

[NARRATOR] Amphibians have only one orifice used for both excretion and reproduction, called a cloaca .

During mating season, changes in this opening makes it relatively easy to determine males from females.

[NATE NAZDROWICZ] Ah, you can tell by the size of the cloaca, the males have a swollen cloaca.

So, for example, here's the cloaca of a female-- right there...here's the cloaca of the male.

The males are swollen.

(Slow guitar music) [NARRATOR] Monitoring includes taking and recording the measurements of each animal.

Since, every tiger has a unique pattern, the amphibian's head is photographed for later recognition, if it is recaptured.

Each salamander is also tagged with a colorful non-toxic elastomer gently injected under the animal's skin, which can be seen using an ultra-violet light.

Finally, to learn more about these endangered amphibians, tiny transmitters were carefully implanted in 12 male tigers.

[NATE NAZDROWICZ] So, here are the stitches, from the surgery that we did to implant that transmitter just right into the side, so we kind of have a good feel for what they're doing in the breeding pond but we really don't know where they go after they leave the breeding pond and what areas they use, uh, so this going to help us-- determine that for this species.

♪ ♪ (Reflective music) [NARRATOR] Throughout the winter, the Delmarva bays continue to fill with water.

Other species quickly take advantage of these temporary pools to reproduce.

Fairy shrimp and copepods soon fill the water below the surface.

Timing is everything in the pools, and not just because of their seasonality.

Soon predators will appear and so by developing early, these smaller creatures have a better chance of fulfilling their life cycle.

By early March, the pools team with life.

The male tigers drop their sperm packets, called spermatophores , which are absorbed by the females, fertilizing their eggs.

They then deposit them in a protective jelly on submerged branches in the deeper areas of the pools.

This is to reduce the chances of the eggs drying out, if the water level drops.

Spotted salamanders follow behind the tigers, with the females depositing their eggs in a similar manner.

Meanwhile, tadpoles feed on algae found on the egg masses of both species, as well as on small plant life near the surface.

(Sound of footsteps) [NARRATOR] A few weeks later and the wired tiger salamanders have left the pool for the surrounding uplands.

The implanted transmitters have a range of 250 feet, with each one tuned to a different frequency.

Finding each salamander requires tuning the directional receiver and listening for a signal.

("Blip" noise from receiver) [NAZDROWICZ] (Aiming receiver) So, it sounds like he's over this way... [NARRATOR] In order to better manage the species, researchers hope to determine not only how far tigers move from the pond, but also what habitat they prefer.

This particular pool is an ideal study site because it is surrounded by three different upland habitats.

[NAZDROWICZ] Oop.

There's one here... (blip from receiver) Oh, I'm getting a strong signal right at this stump...oh yeah, right here, there's a hole going in the ground.

[NARRATOR] Tiger salamanders are carnivorous nocturnal hunters.

At night they appear at the mouth of their burrows, ready to lunge and devour any living creature that happens by and can fit in their mouths.

However, since they can't dig their own burrows, one wonders how they find them and so quickly.

[BRANDON RUHE] Are there so many small mammal burrows in the landscape that the salamanders kind of aimlessly wander, find a burrow, go down or, interestingly, potentially, are they able to latch on to uh, chemical cues from the small mammals themselves?

We kind of informally look for burrows and they're not easy to find, so these salamanders, in the matter of a night, are able leave the pond, find a burrow, and they've been hunkering down for several weeks.

(Calls of frogs and other amphibians) [VOICE] Follow them on the surface... [NARRATOR] It's early April, and the forest is filled with the loud calls of more amphibians.

Three species of frogs have arrived, calling for mates, including Spring peepers... New Jersey chorus... and Southern leopard frogs... [WHITE] This is a Southern leopard frog... and they're calling out in the shallow areas of this Delmarva bay.

They're very common in this area.

You can tell this is a male, you can see the enlarged forearms, the front arms, they look kind of like a body builder...and during breeding season, those arms enlarge, and become much stronger so they can hold the female when they're mating.

[NARRATOR] Frogs are not the only species mating.

Male Eastern newts are using the pool as well to court eligible females.

[WHITE] You see him fanning his tail?

He's fanning his pheromones to entice her to be interested in him, and if she is, eventually he'll drop a spermatophore, that packet of sperm, and then lead her over it, and she'll insert it into her cloaca with her hind legs.

[NARRATOR] Spotted salamanders are using the pool as well, depositing their egg masses.

[NAZDROWICZ] This is a Spotted salamander egg mass... you can see it's fairly rigid, as I pull it out of the water it tends to hold its shape, so there is an outer jelly that kind of surrounds the eggs which are also in a jelly egg...

I'm shining the light from the side here so you can see the embryos inside and their development... and this thick outer coating protects the eggs from predators.

(Eerie music) [NARRATOR] Among those predators are eastern newts, which tear at the outer protective jelly to get to the embryos inside.

In fact, the entire pool, while filled with life, has become an extremely predacious environment.

In response, different species develop in ways that optimize and speed their growth.

[NARRATOR] As vegetarians, tadpoles soon develop hind legs that facilitate their reaching the surface, where more sunlight encourages more plant life.

Meanwhile, salamanders, carnivores from birth, first develop front legs so they can crawl along the pool's bottom and lunge at a passing meal.

But there are not only predatory animal and insect larvae.

Among the many unique plants that thrive in vernal pools is another carnivore.

[BILL MCAVOY] Floating here in the water, let's see if I can find some, is a uh, an aquatic plant, actually a carnivorous plant that you only find in the seasonal ponds when they're flooded, and this is a ultricularia or bladderwort .

As I mentioned, it's a carnivorous plant.

♪ ♪ [NARRATOR] The bladderwort's pretty flower belies its preference for meat.

Small hairs on the plant's bladders sense microscopic organisms that drift by, triggering the bladders' trap doors to open and suck them in where they are digested.

[MCAVOY] It's one way that plants like this get their nutrients.

[NARRATOR] This competition for survival also extends to the pool's surrounding plant community as well.

The annual flooding creates a stressful habitat for upland vegetation.

[MCAVOY] Trees just simply just will not grow in...in this standing water.

That's why it's open and sunny, and when the ponds are open and sunny, that's when the plant species diversity is usually at its highest.

[NARRATOR] Agricultural crops can't grow in standing water either, as Delaware farmers know when planting in fields that once contained these pools.

Known as ghost ponds , these wet depressions dot some Delaware farmlands, and contain fewer and often invasive species.

[MCAVOY] You see here in this depression the Narrow leaf cattail , Typha angustifolia , and species like this get established in these depression wetlands due to the soil that runs off from the surrounding agricultural fields-- and the entire ecology of these seasonal ponds change.

[NARRATOR] For this reason, establishing and maintaining natural habitat buffers around these small unique ecosystems is critical for their ecological health and survival.

(Sound of footsteps in water) [NARRATOR] It's mid-May.

The pools are filling with new arrivals that need monitoring.

Each evening their distinct calls can be recorded and used to document their time at the pools.

[NAZDROWICZ] So, it's springtime and the summer frogs have started to call, so we're out here tonight to set up a frog logger, this is a basic smartphone uh, hooked up to uh, a microphone.

We're going to place the smartphone in a field box, and field the microphone to the outside, so we can get a good quality recording.

We have an app on here uh, that we'll set up uh, to record...every half an hour from dusk until midnight, we'll have it set up throughout the season, so we can monitor uh what species are calling each night and how long they are calling.

(Sounds of frogs calling at dusk) [NARRATOR] As night falls, skilled herpetologists and a team of volunteers prepare to collect data on another endangered species in Delaware, Barking tree frogs.

[NAZDROWICZ] Bring back the frog.

If it has elastomer in the leg, you can leave it, if you can read the tag.

If it has elastomer in the leg and you can't read the tag, just bring it back.

[NARRATOR] The pool is filled with the next cohort of frog species.

All the males are calling at the same time, creating a loud and continuous wall of sound.

[WHITE] In addition to the Barking tree frog, there's other species calling out here in the pond... We have Cricket frogs, which are, if you listen it sounds a little bit like... [various sounds of frog calls] ...marbles clicking together.

Also, there's a trill you hear every once in a while, and that's one of the Gray tree frogs... (sounds of frog calls) There's another species I'm seeing right here, the Green frog... (sounds of frog calls) Of course, all the frogs here that are calling are males, and they're down here in the pond calling away hoping the females will hear them, come down to the pond, and swim over near them and actually touch them.

And then, if that happens, the male will then grab the female in an embrace we call amplexus , and if she's ready to lay her eggs, she will, and he'll fertilize them as they are deposited into the water.

[WHITE] Here's a Barking tree frog, you can see he's still puffed up from calling, when they call, a big large balloon shape, comes from underneath the chin, we call that an external vocal sack, and that sack allows them to call and that amplifies the sound, kind of like a guitar with a hole in it, they are a true tree frog, they can climb and they do live up in the trees when they're not down here mating.

[NAZDROWICZ] 26.5.

[NARRATOR] Back at the processing area, researchers gather morphometric data on each captured frog.

The team carefully takes specific body measurements.

[NAZDROWICZ] And the tibia length.... [NARRATOR] ...noting the weight and sex of each animal.

Finally, they look to see if each frog has been previously caught.

[NAZDROWICZ] ....and this one appears to be a new one... and then Hannah will do the tagging.

[NARRATOR] Injecting a tag through an incision made in small endangered species requires confidence and a very steady hand.

[HANNAH SMALL] In order to identify an individual, we inject alphanumeric tags that are fluorescent.

Each have uh, a significant number to them, which will be then that frog's identifying number.

[NAZDROWICZ] Weight is 15.25.

[NARRATOR] Because the males are calling, they are easier to locate and catch.

But sometimes, the team captures a female.

[NAZDROWICZ] This is a female Barking tree frog.

You can see she is not uh, inflating her throat because she does not call...the female has a very yellow, pale throat, whereas the males tend to have a darker throat.

Uh, this female is, in fact, gravid so I can see some eggs just through the wall of her belly right here, so she came down to the end tonight to mate with a male and lay eggs.

(Up-tempo pensive music) [NARRATOR] It's mid-June, and by now the plant life and trees in the surrounding forest are drawing down the water in the pools through their roots and plant growth.

Delaware scientists now turn their focus to monitoring another endangered species, the Spotted turtle.

These small colorful reptiles are able to survive despite invasive phragmites dominating some of their pools.

[JOE KESSLER] For the Spotted turtles, there's no data as far as...how it effects the Spotted turtles, it does provide cover which is a positive, but...there should be...more native species mixed in there.

[NARRATOR] Spotted turtles can live for decades, but given their small size, they often fall prey to raccoons and wading birds.

After taking size and weight measurements, researchers code each animal by filing a small notch in a unique spot on the carapace.

They record this, along with the overall wear of the shell and any distinctive marks or injuries.

[KESSLER] He's missing a bit of the tip of his tail, so I'll just write that down here, check off "tail" and say, "Tail tip missing," just to try to get as much possible information because when we get these turtles in the future, if we see a new injury, or just an injury at all, we'll be able to go back in our database and just say, "Well, he wasn't like that last time."

♪ ♪ [NARRATOR] Finally, the turtle is photographed from several angles and released.

♪ ♪ [NARRATOR] While, field work continues, the spring's tiger salamander data must be processed.

Unlike, turtles or frogs, the tigers are not given coded markings or tags.

Instead, researchers rely on matching the unique skin patterns of each animal to update their life story.

[NAZDROWICZ] I use the head pattern, uh, of these individuals and compare it to all of our known captures, at this one site.

So, I'm just going to scroll through these basically looking for uh, an individual that matches that pattern.

There we go.

♪ ♪ (Folksy guitar tune) (Din of cicadas in the trees of forest) [NARRATOR] It's summer.

The long hot days mark the peak of the forest's growing season.

The surrounding trees and plants are drawing huge amounts of water from the ground, transforming the pools once again.

[WHITE] It's late August and I'm standing here on the edge of a Delmarva bay.

Six months ago, when I was standing here, when I looked out over the pond, it was ice-covered and full of water.

Right now, it is almost bone dry, and that's the natural cycle of a Delmarva bay.

It's amazing how different this place looks this time of year.

When I was here in late May um, working with the frogs, the Barking tree frogs and all the others, um, the water level was covering this pole, and of course, up over my waist.

We had chest waders on in those days.

This pond was alive with frogs then, a cacophony of sounds... Now, here in the daytime, just so we can see how different it looks without the water.

But this dry-down period...is very important to Delmarva bays.

Without this dry-down, this pond would not be anywhere near as unique and diverse as it is.

When the water disappears...many creatures can't survive here, and the main one, we're talking about is fish.

There are no fish in here because...almost every year, this pond dries down, and the fish would die.

However, there's still lots of other life here.

There are hundreds of little, very small, sub-adult cricket frogs in here.

I'm pointing to one right now, he's about two inches from my finger.

They're only about three quarters of an inch, and these guys were tadpoles not long ago, and they transformed as the water was drying down.

And now, they're sub-adults, and they are going to feed in here until it gets cold in November, and then they will make their way up into the forest around here to hibernate.

(Bright lively music) [NARRATOR] There are also many insects now found in the pool.

Some used its protective spring flooding to establish nests that are now thriving.

Still, others are totally dependent on the pool's draw-down cycle to survive.

[WHITE] Most species of dragonflies lay their eggs in water.

However, there is one that we have here in Delaware called the Blue-faced Meadowhawk .

It happens to be one of our prettiest dragonflies, but they actually lay their eggs in dry pools like this.

They don't lay their eggs when there is water here, they lay them in the dry areas, and then when the water comes, the eggs hatch, and then they become larvae.

[NARRATOR] Like, the Blue-faced Meadowhawk, there are many plant species that rely on the pool's dry-down period to reproduce as well.

[WHITE] This is a really interesting plant called Buttonbush , and it's very common, one of the dominant plants in the Delmarva bays.

It likes to grow where it's very wet, in fact, they can grow in standing water, If you look around, you're going to see it growing throughout the pond.

Now, it does need a dry-down period like we have right now... What I have here are the seed pods of the buttonbush.

About a month ago, this was a flower, a beautiful spherical flower, commonly used by butterflies.

Right below me is a plant that only flowers when the bays are dry, and this is one of the smart weeds, and it's a really important nectar plant, I've seen wasps of several species, butterflies come here very often.

(Guitar music) [NARRATOR] The vernal pools found in southern Delaware have completely dried down as well.

These are open and shallow compared to those found further north.

For this reason, they support a different plant community, including some of Delmarva's, and the planet's, rarest species.

[MCAVOY] This is Rhexa Aristosa, the Awned Meadow-beauty , and this is the only extant population known in the state.

[NARRATOR] As the state botanist, Bill McAvoy is responsible for cataloging and monitoring these rare plant populations.

[MCAVOY] So, here is still another rare plant.

This is Xyris smalliana or Yellow-eyed grass although it's not a grass, but it is state rare, only grows in seasonal ponds.

[NARRATOR] The now dry sunlit area provides a diversity of uniquely adapted flowering plants and grasses that would not otherwise survive, if not for the seasonal flooding that prevents tree growth and perpetual shade.

[MCAVOY] It actually gets a bit amusing, there are so many rare plants in here, but this is Sclerolepis uniflora , also known as the bog button .

Um, this is quite common throughout the pond, although it is a...state rare plant species, another species that only grows in coastal plain seasonal ponds.

[NARRATOR] The pond even hosts species yet to be named.

[MCAVOY] This is that un-described species I mentioned....right here.

[NARRATOR] There is even a plant species extant in only three other places on the planet.

[MCAVOY] This is Dichanthelium Hirstii , or Hirst's panic grass .

And this is actually a globally rare plant.

It's one of the rarest plants in the world in fact, prior to 2012, prior to Hurricane Sandy, the species was quite abundant here in the pond, but Hurricane Sandy dropped a lot of water in this area and the pond was flooded consistently, a matter of fact, it never drew down for several years and that consistent flooding over time really had a negative impact on the species, but fortunately these species, the Hirst panic grass as well as all the species that grow here in the pond are able to seed bank, their seeds can remain viable in the soil for decades.

So, when some of these rare plants begin to decline in these ponds, I really don't worry about it too much because I know, it's in the seed bank as long as we maintain the habitat, we preserve the areas around it, I know...these species will persist here in the pond.

(Birds chirping) [NARRATOR] It's October.

The leaves are falling and the pools are at their driest.

[ALISON B. ROGERSON] The water table is lower, it's been dry, the end of the summer, and as the winter comes in, and we get a lot of winter rains, these will replenish, and fill up and by January this will be holding over a foot of water.

[NARRATOR] It's an ideal time for natural resource personnel to assess and monitor these unusual seasonal wetlands.

[MARK A. BIDDLE] For 20 years now, we've been monitoring and assessing wetlands across the state, and what that tells us is how healthy the watershed is in general... [ERIN] We're actually are going to do deviation... [BIDDLE] We assess the wetlands by type in each watershed, so there's riverine wetlands, there's tidal wetlands, there's forested flats, and then there are depressions like, a Delmarva bay like this.

[NARRATOR] Monitoring includes taking sample cores of the soil found in the vernal pool basin.

This means, boring down far enough to find the water table, and then noting the soil column's characteristics.

[BIDDLE] Really high clay content in that one and you can see how sticky it is...because it creates ribbons, is what they're known as, you can squeeze it out like that, and it just shows it's so dark, it has a really high organic content, and it's been that way for a long period of time.

Now in other re-dox situations, there might be like an orange clay, and that's because it has a higher iron content, uh, so we'll see different types of soil, so that's one of the reasons why we do the soil borings to evaluate the soil types here.

[NARRATOR] The team also notes the condition of the plants and trees in a measured area.

[RESEARCHER] Thirty-five centimeters.

[ERIN DORSET] We measure the largest ones...

Sometimes, we also measure some of the smaller ones just to get a comparison and get a full picture of um, all of the plants that are in there.

[RESEARCHER 2] I'd say we went 24 inches, about two feet.. [BIDDLE] They collect a lot of data on the vegetation, the soils...any wildlife that might be using it, the hydrology...and for each watershed uh, they put together a big scientific report that's very detailed with the data... We also put together a more public facing document, sort of a wetland health report card by watershed, and that's just a few page document that grades the wetland types and how healthy they are in each watershed.

(Reflective up-tempo music) [NARRATOR] These reports are used by natural resource managers for planning and environmental improvement work, and available for local, and county officials to help guide their land use planning decisions.

♪ ♪ As unique indicators for much of Delaware's ground water, vernal pools are also regularly monitored for water quality with multiple wells.

But now they are the focus of climate change studies too.

Like all wetlands, they absorb carbon from the atmosphere.

[BRUCE VASILAS] There's been a lot of work done with carbon sequestration in tidal marshes, not much has been done with these vernal pools or Delmarva bays.

So, this is basically a carbon cycle study, so we are measuring um, inputs like leaves, branches, and we're also measuring decomposition rates.

[NARRATOR] To determine decomposition rates, Dr. Vasilas measures the carbon lost over time from carbon rods secured to the ground in and around the pond.

To measure carbon coming into the pool, sample collection trays are placed in strategic locations, which gather falling leaves and organic material.

These are emptied periodically and the contents brought back to the University of Delaware's Soil Testing Lab.

Here, each tray's contents are weighed, and samples processed twice to determine how much carbon is being collected in the pool.

[KAREN GARTLEY] We weigh the sample out, we burn it at a low temperature, which is 360 degrees Celsius, and after two hours we've burned off all that available organic matter.

Um, the difference between the before-weight and the after-weight is actually the carbon that was lost, and that's converted into an organic matter percentage in the soil.

[NARRATOR] The remaining inorganic carbon is burned off in a much hotter oven at a much higher temperature.

This five-year study is proving that the unique hydrologic and plant life cycles of these seasonal wetlands significantly promotes carbon sequestration.

[KAREN GARTLEY] You've got moisture, you've got soil microbes there, they come and go with the freezing, and the thawing, and all those processes that will help draw carbon into the soil and also make it available to the microbes, the plant roots, all those things that help tie up the carbon in the soil.

(Bright folksy music) [NARRATOR] The more we learn about these seasonal freshwater wetlands, the more we realize their value, not just for the unusual life they support, but for us as well.

Yet ironically, it's their very uniqueness that often means their true value is overlooked.

[BIDDLE] Because they're so small, you can impact them easily, so we see a lot of them that get filled, we see a lot of them that either have development that has encroached upon them and what that does is then takes away the wetland functions, the beneficial functions that they provide.

[NARRATOR] Unfortunately, Delaware has lost fully half of these rare habitats to date.

While, Delaware regulates tidal wetlands, the federal government, through the Clean Water Act, regulates the state's freshwater resources.

That Act is now half a century old and never considered these small, isolated wetlands.

[BIDDLE] When that was first written, there was not a lot of knowledge about how wetlands functioned and their importance, so there's certain language in the Clean Water Act that looks at connectivity or adjacency to traditional navigable waters.

(Reflective music with guitar) [NARRATOR] The 50-year-old federal legislation only regulates freshwater resources that are obviously connected to one another, such as streams, lakes, and rivers.

But recent research has shown vernal pools are connected to these other water bodies through shallow groundwater exchange.

Yet, because they were thought to be isolated, they remain unregulated by the federal government and the state.

(Pensive piano music builds) [NARRATOR] A year has passed, and the hydrologic cycle of vernal pools is about to begin again.

When they flood, diverse and rare life forms will be drawn to them, relying on their waters to support their critical life stages.

People are now also drawn to them as well, and value them for their own reasons.

In Virginia's Allegheny Mountains, Diana Kling Smith and her brother have been working hard to bring back a local mountain pool tied to many childhood memories.

[DIANA KLING SMITH] Back in the '50s, early '60s, um, we would...it was a... playground for us... we would come up and ice skate out in this, primarily this area here.

[NARRATOR] But in recent years, the ridge line near the pool was excavated, altering the area's water table and the pool's hydrologic cycle.

With reduced annual flooding, greenbrier and persimmon trees soon took over.

[SMITH] The greenbrier was practically covering the whole area.

I mean, you couldn't hardly get to where we used to ice-skate.

[NARRATOR] For three months, Diana and her brother cleared the prickly invader and other low-lying vegetation from the pool basin.

[SMITH] What you see piled back, all that brown is what we have cleared...all the way around.

[NARRATOR] They since removed the persimmon trees as well, restoring the habitat to encourage the return of its unique species, and relive a cherished childhood memory.

[SMITH] That was our goal, was to clear it, so that at least one more winter it looks like...I remember it.

(Pensive piano music builds) [NARRATOR] Meanwhile, down the mountain in the floodplain of the Cow Pasture River, Dave Peters, with Mike Hayslett's guidance, has restored a seasonal pond on his farm.

Originally, drained for cropland, they've diked one field's drainage ditch with remarkable results.

[HAYSLETT] In plugging the ditch, we were able to prevent the loss of a lot of the seasonal water that accumulates here, and that has enriched the wetland, and enabled it to serve more, things like, breeding amphibians that come from the adjoining forest.

[NARRATOR] To have such a habitat on his land is not lost on Dave Peters either.

[DAVE PETERS] Not everybody can go out and find a Marbled salamander or a Wood frog, and uh, it's just the uniqueness of having that.

♪ ♪ [NARRATOR] But appreciating that uniqueness is also matched with his growing awareness of the overall value of a seasonal wetland.

[PETERS] I'm really aware now of how...small areas of wetlands can do a lot of protecting and correcting errors that we do....and I like the thought that I can help protect some things that have lost their habitat.

(Calls of frogs and other amphibians) [NARRATOR] Documenting the rich community of life that dwells in vernal pools is another way that builds awareness of them, which is what Steven Johnson has committed to with his career.

[JOHNSON] I feel like, part of my work in photography is that kind of education, because it can be easy to think of something like this as just being a puddle, and really there's so much more going on.

♪ ♪ [NARRATOR] Which is what Delaware college students are realizing the next spring as they explore a nearby Delmarva bay with Jim White and Nate Nazdrowicz.

[STUDENT] And that's done with like a...stamp?

[NAZDROWICZ] No, this is under the skin.

I do a little slit...in the leg and I insert a flat needle that has this tag inside it.

[WHITE] And then, we had another good find, Marbled salamander, and then we had also a Green frog.

So, just write those three species down... (holds up a frog) Wank, wank, wank... (students laughs) (More calls of frogs and amphibians at night) [NARRATOR] Introducing future generations to the pool's unique residents is perhaps the best way to build the greater awareness needed to protect these small, yet, incredibly diverse ecosystems.

[MAYA WALKER] This is a Gray tree frog, um, Hyla Versacolor ...they're usually found on the trees along the edge.

Um, I caught him like about 20 minutes ago and he's just been chilling on the edge of my pole this whole time.

I've always been a Herp fan, but this has been good chance for me to learn my "IDs," my Delmarva "IDs," learn about the habitats of Delmarva, um, vernal pools, you know, I really didn't know what those were before I took this class so... (Student talks to Maya and Maya responds) I know, I feel like, I should take him home as a friend.

[JULIA IOVINO] A Southern leopard frog, um, they have like a call that kind of sounds like a laugh, it's like a chuckle, they're harder to find than the green frogs are in here.

[PRODUCER] So, you enjoy this class?

[IOVINO] I love this class.

[PRODUCER] Important to protect these ponds?

[IOVINO] Absolutely.

[PRODUCER] --Yeah.

They're very unique.

[IOVINO] They are, and they're so cool, especially like coming from a suburban area, like coming out here, is so great.

♪ ♪ [WHITE] I'm glad we got pretty lucky, we heard all the frogs.

[NARRATOR] Whether, on a mountain or coastal plain, each vernal pool is a discrete ecosystem with all the complexity found in those often profiled in nature documentaries.

These small pools demand as many adaptive behaviors and survival strategies from their inhabitants as the larger habitats do, albeit on a smaller scale.

And because of their ancient wet-dry cycle, they support some of the most unusual and rare species in the animal and plant world.

♪ ♪ But because vernal pools are small, isolated and often located "just nearby" means their value is often overlooked and even ignored.

Current land use practices perpetuate this.

Until we act on what we've learned about these ecosystems over the last 50 years, we'll continue to lose these unique, fascinating communities of life.

Only by understanding vernal pools through continuing research, environmental education, and simple acts of caring, will we in time recognize their full ecological value and then hopefully better protect these wetlands of wonder.

(Music fades up) ♪ ♪