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Vernal pools are a vital natural resource.
They offer many important benefits including serving as a breeding
site for several amphibian species as well as a habitat for
rare and endangered plant species. Vernal pools also filter
the rainwater that ultimately drains into our water supply.
Unfortunately, they are frequently overlooked.
Vernal
pools by definition are small, isolated wetlands that retain
water on a seasonal basis.1 Sometimes referred to as spring
pools, vernal pools fill up with melting snow and early
rains during spring, then usually dry up by mid to late summer
depending on the pool depth, permeability of the soil, and amount
of rainfall. Some relatively deep pools may remain flooded for
a few years but become completely dry in seasons with very low
rainfall. Found on every continent except Antarctica, vernal
pools come in sizes ranging from several square feet to several
acres. The sites where they occur also vary greatly and include
isolated depressions in the woods, kettle holes, and gravel
pits.
Nearly 50 percent of the amphibians in the
U.S. breed primarily in vernal pools because the pools are temporary
and cannot support fish, the major predator to amphibian larvae.2
Some species like the wood frog and the spotted salamander are
obligate species meaning they will not breed in any body of
water other than a vernal pool.
Vernal pools also support several species
of insects including predacious diving beetles and crawling
water beetles. These insects, along with dragonfly nymphs and
the larvae of several salamander species, are voracious predators
of mosquito larvae referred to as wigglers. Certain
species of adult frogs, toads and salamanders feed on adult
mosquitoes as well. The many predators that reside at vernal
pools make them a hostile environment for mosquitoes as compared
to the many man-made mosquito breeding sites such as bird baths,
clogged gutters, and swimming pools that are not properly winterized.
We need to recognize and preserve vernal pools
for the vital and dynamic natural resources that they are. For
more information, try these Internet links:
Environmental
Protection Agency
The Vernal
Pool Association
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