Vernal Pool Breeders
(Conservation Currents, Northern Virginia Soil and Water Conservation District, June 2004)
Vernal pools are small, isolated wetlands that retain water on a temporary or seasonal basis. Many amphibian species in the U.S. breed primarily in vernal pools because the pools are temporary and cannot support fish, the major predator to amphibian larvae. Some species, such as the wood frog and the spotted salamander, are obligate species, meaning they will not breed in any body of water other than a vernal pool.
Save the Forest!
Vernal pool breeders reside at the pool only during their brief breeding season. The rest of the year, they live in the upland forest surrounding the pool. Getting to their “birth pool” can be a dangerous endeavor for vernal pool breeders if the upland forest around the pool has been partially cleared.
For example, where large areas of forest around pools have been cleared to create pastureland, there is a hazardous barrier between the animals’ home and breeding site. The animals are forced to trek across open land making them vulnerable to predators and to being trampled by horses or cattle. Therefore, having a generous amount of contiguous forest around the breeding site is very important.
Follow That Scent
Spotted, mole, and other salamander species have an internal “homing device” that leads them to the same breeding pool each year. Here’s how it works. Salamander eggs are contained in a jelly-like mass that the larvae will use for sustenance after they hatch. Several days after being laid, algae will grow on the “jelly.” As the larvae hatch and feed on the algae-covered jelly, the unique properties of the algae become genetically imprinted on the larvae’s brain. The larvae that survive and “morph” into junior adults will venture into the upland forest with the “memory” of their birth pool’s algae scent. Once reaching sexual maturity, the animals are drawn to their “birth pool” each breeding season by the smell of the algae.
Vernal pools provide many amphibians a place to breed. Unfortunately, like other wetlands they are disappearing at an alarming rate. We need to preserve these dynamic natural resources so that future generations can discover the fascinating life that they support.
Go to Vernal Pools—an Overlooked Natural Resource for more information.