- August 19, 2015
For some species, known collectively as obligate species, Vernal Pools are the only habitat where reproduction occurs. Any evidence of active breeding by any one of these species confirms that a body of water is a vernal pool. This distinction plays a big role in conservation efforts and environmental legislation. Obligate species will vary by state or region but usually include salamanders, frogs and some crustaceans.
Obligate amphibian species, like mole salamanders and Wood frogs, live as terrestrial adults then travel to vernal pools to lay their eggs shortly after the first spring rain. An estimated 85% of obligate amphibians return each year to breed in the same pond where they were born, 1 bypassing other suitable pools and navigating man-made obstacles like roads, construction sites, and golf courses.
Once they reach the pools they deposit gelatinous clusters of eggs under the water’s surface. After the eggs hatch, larvae must grow quickly, reach maturity, and leave the pool before before it dries up for the remainder of the year.
Those that do not are easy food for birds and other predators, becoming more and more exposed as the water area disappears.
Several crustaceans, like fairy shrimp and clam shrimp, are obligate species. These shrimp lay eggs that sink to the bottom of the pool and dry out in the summer, freeze in the winter and hatch when the water returns in the spring, completing the cycle again 2.
Other species, which take advantage of the lush environment of vernal pools but can also use different types of breeding and foraging habitats, are called facultative species.
Facultative species may include:
- Invertebrates like dragonfly, damselfly and caddisfly larvae. These are sensitive species and are an indicator of healthy aquatic environments 3.
- Birds, like herons, geese and ducks, that that feed on invertebrates and high-protein vegetation in and around vernal pools 4.
- Reptiles, like turtles and snakes, that prey on crustaceans and other invertebrates.
- Mammals like deer, raccoon, and mice that use vernal pools for drinking water, bathing and feeding on plants, amphibians and crustaceans.
Vernal pools also support some unique flowering plants. Spring ephemerals are plants that make a brief above ground appearance when the weather begins to warm. Like the pools that spur them, they are short lived. After blooming and setting seed they lose their foliage storing gained energy in their roots to wait for the next year.
Add a Vernal Pool to Your Map
Those lucky enough to have large properties may find they include vernal pools. If you aren’t sure, make a plan to walk your property during your next wet season. For many this will be Spring, but for others in more moderate climates (like on the West Coast), this might be during a winter rainy season.
Use the water habitat type to map vernal pools ().
Set the characteristics for this object
Once you’ve added the pool to your map make sure to set the characteristics. Click on the object, and open the infowindow to access these settings under “characteristics.”
First set “running water” to “standing” water.
2nd, set seasonality to “seasonal.”
Don’t have a map yet? Start One Now
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- Colburn, E. A., 2004. Vernal Pools. Natural History and Conservation. McNaughton & Gunn, Inc., Saline, MI. ↩
- Colburn, Elizabeth A., Weeks, Stephen C., Reed, Sadie K. Diversity and Ecology of Vernal Pool Invertebrates. ↩
- U.S. EPA. Invertebrates as Indicators. 3 December 2008. ↩
- Silveire, Joseph G. Avian Uses of Vernal Pools and Implications for Conservation Practice. ↩