Vernal Pools Vernal Pools Vernal pools are temporary bodies of water that flood each year for a few months during the spring and summer. Some relatively deep pools may remain flooded for a few years but become completely dry in seasons with very low rainfall. Autumnal pools fill during the fall with rising groundwater. Because vernal pools are not permanently flooded, they do not support fish populations and thus provide safe breeding sites for several amphibian and invertebrate species, including wood frogs, spotted salamanders, and fairy shrimp. These species have evolved life cycles that depend on temporary pools.
Vernal pools vary in size, ranging from several square feet to several acres.
They can be found in a variety of sites, such as isolated depressions in the woods, kettle holes, and gravel pits. Many are within larger wetlands, such as oxbows in river floodplains and pools in forested swamps or scrub-shrub wetlands. Their common characteristics are the absence of fish, temporary flooding regime, and the presence of vernal pool species. Suitable pools must have enough leaf litter and other debris to provide food sources and cover for the species that breed in them. The short flooding duration of vernal pools favors species that can carry out their breeding cycle very quickly.