Vernal Pools Critical Habitats, Ephemeral Wetlands
April 22, 2001

What is a vernal pool? Recently a visitor from Michigan, who had been searching for information on the subject for a year, brought in materials to share with Woodland Dunes staff, naturalists and columnist. the subject is of such interest, and yet so relatively unfamiliar, it bears sharing.

The following definition, found in the provided literature, obviously mean the same thing, but collectively provide a definition.

1) Vernal pools are critical habitats that support unique and valuable communities.
2) Vernal pools are ephemeral wetlands which fill annually from precipitation, runoff and rising ground water. Most years they become completely dry. the wet-dry cycle prevents fish from becoming established, but they are rich temporary habitat for other creatures.
3) Consider vernal pools as wetlands that are or become isolated while containing water used by indicated species and have wet and dry cycles. No fish, which would be predatory on the other creatures are present.
4) Variable in appearance, water source, time of filling, surrounding habitat and animal content as well as other factors, they all share two characteristics; they do not hold water permanently and are free of breeding populations of fish.
5) In a narrow sense, a vernal pool is a temporary fish-free wetland which fills each spring and dries annually.
6) Popular use of "vernal pool"; temporary wetlands, regardless if and when, full or dry, that support certain animal communities.
7) Vernal pools are any fish-free, temporary wetlands that support indicator species.

What, and who are indicator species? There are two kinds called "obligate", or direct species that are completely dependent on vernal pools such as fairy shrimp and caddisfly larva. Their life cycle is adapted to the wet and dry situation. the species that use the pools during the breeding season, but spend time on land, such as salamanders, frogs and toads are called "facultive" or indirect species.

This information was gleaned from the "Maine Citizens Guide to Locating Vernal Pools" published by the Maine Audubon Society, "A Field Guide to the Animals of Vernal Pools" published by government programs from Massachusetts and donated to the Woodland Dunes library by the Michigan visitor, J.F. Will, and A Vernal Pool Resource Kit for Educators, entitled "Diving into Wicked Big Puddles" complete with one hundred slides, was loaned for staff perusal.

Needless to say, the material is a welcome addition for the teacher naturalists who have volunteered to teach third graders during the upcoming Amphibmeander program. Some of the creatures they will encounter will be from the 'Dunes' vernal pools and will provide material for future articles.

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