The Nature of Spring: Vernal Pools
Spring is in the air, the water, the soil, and on land. It is also in the drive of many animals and plants to continue their kind. With so much happening in spring, keeping track of all the activity can be difficult, but it is well worth the effort.
Most wetlands are defined by the presence of wet (hydric) soils and special plants that thrive in wetlands. In contrast, vernal pools lack these soils and plants. They are defined largely by the presence of certain amphibians that breed only in these temporary pools and by the absence of fish.
Amphibians which breed only in vernal pools include wood frogs, spotted salamanders, blue spotted salamanders, marbled salamanders, and Jefferson salamanders. These animals use the pool for breeding, but otherwise spend most of their time in the surrounding area. The adults pair and mate shortly after ice-out, then the females lay their gelatinous egg masses in the pools, often attaching them to sticks. The eggs must develop quickly and the juveniles must grow quickly, too. When the juveniles grow too slowly or the pool dries too quickly, the young amphibians may not survive.
Although vernal pools do not have fish to eat the eggs, they are favorite food source for turtles that journey around the landscape. Endangered Blanding’s turtles and rare spotted and wood turtles make extensive use of vernal pools.
Because they are temporary and often go unnoticed by large-scale survey methods, vernal pools are very susceptible to damage or destruction caused by human activity such as development. If they are filled or built on, they cease to be valuable habitat. Similarly, if the area around a vernal pool is developed, the adults may be lost.
A different problem happens when vernal pools are cut off from other vernal pools or important habitat by roads, power-line corridors, or habitat fragmentation. Fragmentation occurs when a large area of land becomes a patchwork of homes, businesses, roads, etc., even though some smaller natural areas are still present. Protecting one isolated vernal pool and the surrounding area is helpful for a few years, but eventually, the populations of amphibians may become impaired by a lack of genetic diversity. Small populations cannot survive well in isolation. Protecting an area with a group of vernal pools that can remain in a natural state will bring more and greater benefits to the creatures of vernal pools and to the entire ecosystem.
Vernal pools are important to the proper functioning of our landscape, and they are fascinating places to visit. If you find a vernal pool, please take the opportunity to look for egg masses and the critters that made them. As always, tread lightly and handle with care, leaving no trace of your visit.
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