The sights and sounds at vernal pools have picked up in the last few weeks here in Vermont! Wood frogs are calling, spotted salamanders are migrating to lay their eggs, and fairy shrimp are waking up from a long rest. Vernal pools can occur just about anywhere if the conditions are right but are typically found in forested areas. In most years in Vermont, anywhere between March and April is when vernal pools become more obvious, filling up with water from melting snow and frequent spring rains.
What is a vernal pool?
According to Vermont Center for Ecostudies, vernal pools are:
1. Small shallow wetlands with well-defined boundaries that lack a permanent inlet or outlet
2. Formed primarily by seasonal snow melt and rain
3. Tend to dry out in mid to late summer, providing a seasonal hydroperiod of no less than 3 months after ice out
4. Provide critical habitat for a wide variety of animals, including breeding amphibians such as spotted salamander and wood frog
5. Lack suitable habitat for fish
6. Little to no vegetation growing out of the water
A wide variety of animals and birds can be found at vernal pools, however, the presence of certain indicator species or their eggs provides further evidence of a vernal pool. These species rely on certain environmental conditions and hydroperiods for survival. In Vermont, there are five species that are considered vernal pool indicators. These include:
- Spotted Salamander (Ambystoma maculatum) and their egg masses
- Wood Frog (Lithobates sylvatica) and their egg masses
- Jefferson Salamander (Ambystoma jeffersonianum) and their egg masses
- Blue-spotted Salamander (Ambystoma laterale) and their egg masses
- Fairy Shrimp (Eubranchipus sp.)-to learn more about these fascinating creatures, click here to read our blog post from March!
The presence of these species or their egg masses usually (with exceptions) indicates a vernal pool. The amphibian species listed above are typically forest dwellers, and need vernal pools that are close by where they can lay their eggs. Vernal pools provide critical breeding habitat for these species and although there are instances where these species can breed in other wetlands, they prefer and rely heavily on vernal pools for their survival and longevity.
Amphibians are cold-blooded creatures that usually spend the first part of their life in water with gills and the second part of their life out of the water with lungs. The word amphibian comes from Greek “amphi” which means double and “bios” which means life. Vernal pools provide habitat for the necessary time frame from eggs to adult. Because vernal pools usually dry up later in the summer, fish are unable to survive. The lack of fish presence provides protection from predation while the eggs and larvae are developing. However, a wide variety of animals and birds love to snack on eggs and tadpoles in vernal pools. These include Owl, Hawk, Snakes, Bear, Mink, Bobcat, and Raccoon. Other amphibians such as Spring Peepers, Gray Tree Frogs, American Toads, Bull Frogs and Green Frogs might make an appearance at a vernal pool, either to lay eggs or stop by for a swim, but have more flexibility to breed in other types of permanent wetlands. Fingernail clams, caddisflies, dragonflies, and water boatmen also thrive in vernal pools and often use them for breeding.
Why are they important?
Vernal pools are considered keystone ecosystems and serve as critical breeding habitat for a variety of species, including several that have been deemed a high or medium priority of greatest conservation need. These include Jefferson, Spotted, and Blue Spotted Salamanders. Check out the Vermont Reptile and Amphibian Atlas to learn more!
Vernal Pools are also essential components to a healthy and diverse forest ecosystem. Climate change poses a serious threat to vernal pools. Additionally, because vernal pools dry up each year or stay dry for several years before filling up again, they are not always obvious, making them highly susceptible to development and conversion away from forested habitats.
How you can get involved!
Early on, Vermont Center for Ecostudies (VCE) recognized that knowing where vernal pools are is critical to their conservation and protection. Initially started as a project in 2008 between VCE and Arrowwood Environmental became a statewide project in collaboration with Vermont Fish & Wildlife to map as many vernal pools as possible. Each year, professionals and volunteers alike submit data and locations of vernal pools to the atlas, building an excellent database of vernal pools that will help protect and conserve these vulnerable wetlands. In 2018, the Vernal Pool Monitoring Project was also established. Volunteers monitor vernal pools throughout the year and observe and collect a vast amount of data to help us better understand the current state of vernal pools in Vermont.
Both of these projects are essential to understanding and protecting vernal pools. If you’d like to get involved with the Vermont Vernal Pool Atlas or the Vernal Pool Monitoring Project, visit the Vermont Center for Ecostudies Website!
A special thanks to Conservation Biologist Steve Faccio from Vermont Center for Ecostudies for presenting all about Vernal Pools for our Spring Speaker Series. To watch the recording of that presentation, click here!