What is a Vernal Cache?
Physical description of a vernal pool
A vernal pool is a contained basin depression lacking a
permanent above ground outlet. In the Northeast, it fills with
water with the rising water table of fall and winter or with the
melt-water and runoff of winter and spring snow and rain. Many
vernal pools in the Northeast are covered with ice in the winter
months. They contain water for a few months in the spring and early
summer. By late summer, a vernal pool is generally (but not always)
dry. Below are views of the same pool at three different times of
the year
Biological description of a vernal pool
A vernal pool, because of its periodic drying, does not support
breeding populations of fish. Many organisms have evolved to use a
temporary wetland which will dry but where they are not eaten by
fish. These organisms are the "obligate" vernal pool species, so
called because they must use a vernal pool for various parts of
their life cycle. If the obligate species are using a body of
water, then that water is a vernal pool. In New England, the easily
recognizable obligate species are the fairy shrimp, the mole
salamanders and the wood frog. Fairy shrimp are small (about 1
inch) crustaceans which spend their entire lives ( a few weeks) in
a vernal pool. Eggs hatch in late winter/early spring and adults
may be observed in pools in the spring. Females eventually drop an
egg case which remains on the pool bottom after the pool dries. The
eggs pass through a cycle of drying and freezing, and then hatch
another year when water returns. The presence of fairy shrimp
indicates that a water body is a vernal pool. Wood frogs are an
amphibian species of upland forests. They venture to vernal pools
in early spring, lay their eggs, and return to the moist woodland
for the remainder of the year. The tadpoles develop in the pool and
eventually follow the adults to adjacent uplands. The presence of
evidence of breeding by wood frogs (chorusing or mating adults, egg
masses or tadpoles) indicates that a pool is a vernal pool. The
mole salamanders are also upland organisms. They spend most of
their lives in burrows on the forest floor. Annually, on certain
rainy nights, they migrate to ancestral vernal pools to mate and
lay their eggs. They soon return to the upland. The eggs develop in
the pool and, by the time the pool dries, the young emerge to begin
their life as a terrestrial animal. Evidence that mole salamanders
breed in an area, make that water body a vernal pool. Breeding
evidence would be a breeding congress, spermatophores, egg masses
or larvae.
The vernal pools surrounding Mt. Agamenticus are one of the few
remaining locations essential to the survival of Blandings turtles
in Maine.
Special Thanks to the Vernal Pool at www.vernalpool.org for the
description of vernal pools and it’s inhabitants.
The Mount Agamenticus Conservation Region contains over 10,000
acres of land and is one of the largest remaining unfragmented
forests in coastal New England. The region is known for its
abundance of vernal pools, rich biodiversity, and unique trail
system and is also home to many of Maine’s rare plants and
animals.
State, local and non-profit landowners are working together to
protect this land and to balance wildlife and water quality along
with sustainable recreation. These landowners make up the Mount
Agamenticus Steering Committee and include: the Towns of York and
South Berwick, The York Water District, Maine Dept. of Inland
Fisheries and Wildlife, Great Works Regional Land Trust, York Land
Trust, and The Nature Conservancy.
As you enjoy the land around Mount Agamenticus please follow the
guidelines for use (posted in the summit kiosk) and treat the land
and wildlife with respect. Remember that this area contains fragile
habitat and is unlike any place else on earth. Its conservation
depends on you!
The Mount Agamenticus Conservation Coordinator may be contacted
at 186 York Street, York, ME or (207) 361-1102
