Vernal Pools and Springtime Symphonies

(Editors note: This post is adapted from a piece written by PBC Senior Program Manager Ron Franco, who regularly highlights natural and seasonal phenomena to enhance staff knowledge.)

With everything else going on at this moment in time, it might easily be overlooked that it is again the right time of year for us to listen to the sweet symphony of spring peepers and their merry band of amphibian friends! As Old Man Winter relents, our spritely amphibian neighbors gear up for a productive reproductive spring. Today’s topic, vernal pools, play an incredibly important role for local species such as the Spring Peeper, Wood Frog, Bull Frogs, Pickerel Frog, and many others.

Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide a unique type of wetland habitat. They are typically small, shallow, ephemeral water bodies, and unlike a pond or a lake, they have no permanent inlet or outlet. To be considered a vernal pool, a depression must hold water for at least two consecutive months, typically between February and June. Pools are filled each spring by rain and snow melt, then dry up during the summer.

Why are vernal pools important?
Vernal pools serve as essential breeding habitat for certain species of wildlife, including salamanders and frogs (amphibians). Vernal pools lack breeding fish populations. The absence of fish is an essential characteristic of these ecosystems, as fish are highly predatory on amphibian eggs and larvae. In addition to being critical for amphibians, vernal pools provide habitat to many species of insects, reptiles, plants, and other wildlife. 

Over the course of evolution, several species of salamanders and frogs came to rely on these fish-free water bodies. Today, these species exhibit "hardwired" instincts and behaviors that are geared exclusively towards this kind of aquatic habitat.

Species that are dependent upon vernal pools are known as "obligate vernal pool breeders." In New Jersey there are seven species - two frogs and five salamanders - that fit this category. Another 14 of New Jersey's amphibians also use vernal pools for breeding, but unlike the 'obligate' species, these species can successfully reproduce in habitats that contain fish. These species are known as "facultative vernal pool breeders."

Wow! Vernal pools play such an amazing important ephemeral role in keeping our Northern New Jersey Woodland Eco-system healthy and happy! Keep an ear out for the amphibian choruses of spring evenings – when you hear frogs calling, you’ll know that a vernal pool is to thank!