Fleeting Ephemeral Pools

04/12/2018

Tis the season for muddy driveways, wiping the dog’s feet before he comes tromping through the house, and depositing boots by the door in an attempt to keep the floors clean. Spring temperatures rise and fall, and between the rain and the melting snow, the land seems soggy and sloppy. Amidst the puddles and the potholes, there are some small bodies of water that appear fleetingly and are the life line for several wildlife species.

Each spring, small wetland-like pools of water fill up for a few short weeks before disappearing again with the heat of summer. Referred to as vernal or ephemeral pools, these little bodies of water, sometimes nothing more than a puddle really, are the staging place for the beginnings of life for numerous wildlife species that pass through an aquatic phase of life. The pools offer a relatively safe place for a variety of amphibians and insects to lay their eggs. Offspring then spend their first life-cycle in habitats with reduced competition and predation than would be found in larger ponds. Fish are unable to populate ephemeral pools because the pools do not contain water throughout the year. A lack of year-round water supply limits inhabitants to species that pass through an aquatic phase of life before metamorphizing into a terrestrial form.

Amphibian species that take advantage of vernal pools include wood frogs, red-spotted newts, and mole salamanders such as spotted salamanders. Many of these animals lay their eggs in the exact same pool in which they were born, passing by seemingly suitable pools on the way. Many insect species also take advantage of ephemeral pools to lay their eggs. The nymphs of dragonflies, for example, are as fierce as under-water predators as they are in the sky, often taking small fish or tadpoles for prey. Insects have less of a homing mechanism than frogs and salamanders and will lay their eggs in any vernal pool that satisfies. Destruction of ephemeral pools for agriculture and development is considered a conservation issue for any species with a threatened status that utilizes them. One challenge, of course, is determining where important ephemeral pools are located in order to protect them during the months in which they are dry.

While we humans are fighting to keep the mud and slop out of our houses and cars, the return of warmer weather brings with it the fleeting existence of ephemeral pools and the miraculous life they sustain.


Story and photo by Gabrielle L. Wheeler