Vernal pools are
temporary pools found throughout Pennsylvania’s forests that lose all or most
of their water during the summer and slowly refill during the fall and winter. They reach their maximum size after snow melt and spring rains -- just in time for
the arrival of breeding amphibians, insects, and crustaceans. Vernal pools are choice breeding spots
because their dry periods reduce or eliminate predators such as fish and
bullfrogs, providing an ideal nursery.
While the dry
period lessens predation for vernal pool species, a temporary habitat creates
an unpredictable living situation. To
adapt to this temporary habitat, many species have an aquatic immature phase
and leave as terrestrial adults before the pool dries, and many insects and
crustaceans lay tough eggs that can lie dormant until water returns to the
pool.
In Pennsylvania, some of the easily recognizable obligate species are mole salamanders, wood frogs, and fairy shrimp. Obligate species must use a vernal pool for various parts of their life cycle and that’s why protecting vernal pools and the surrounding 1,000 feet of land from poorly planned development is critical for protecting amphibian species.
Habitat loss and fragmentation as well as changes in hydrology and water chemistry are all threats to the species that rely on vernal pools. To learn more about vernal pools, check out these upcoming guided hikes in Cumberland County.
Jen Quinn is central Pennsylvania outreach coordinator for PennFuture and is based in Harrisburg.
