Vernal Pools: Murky Puddles of Fascinating Life
The word vernal is Latin from “vernus,” meaning “belonging to spring.” Vernal pools refer to any wetland that fills annually from snow melt, spring rains and rising groundwater. They usually do not have an outlet stream and therefore most years dry out during the hot summer months or early fall. But don’t let these vanishing pools fool you.
Vernal pools are typically small, perhaps even a ‘vernal puddle’, but ecologically extremely important as they erupt with unique creatures in early spring when ice and snow melt and warm spring rains fall. They can be discovered in forests and fields, and even old tractor ruts. Vernal pools are valuable wildlife habitats because of the great variety of species that call them home. Being an aquatic organism and living in a habitat that normally dries up in a few months can be tricky. The organisms that live in vernal pools have adapted amazing survival strategies. Most important is rapid growth from egg to larva to adult. This development can be accelerated by warm water temperatures and even shrinking water levels. Some of the adults fly, hop or crawl away, while others remain dormant and wait out dry conditions. Some species may survive dormancy as adults, larvae or eggs for several years until the pond becomes flooded again. Low oxygen levels and regular drying prevents the establishment of fish and large frog species from surviving and preying on eggs and larva in vernal pools, thus providing some refuge for those species that call these ponds home.
Indicator species (sometimes called obligate species), such as wood frogs, spotted salamanders and fairy shrimp distinguish vernal pools. These organisms depend solely on vernal pools for their survival. Facultative species, on the other hand, can be found in vernal pools but are capable of inhabiting a variety of wetland habitats for their various life activities. Facultative species include red-spotted newts, spring peepers, gray treefrogs, toads, predaceous diving beetles, fingernail clams, amphibious snails, caddisfly larvae, dragonfly and damselfly nymphs and many more.
The foundation of food webs in a vernal pool is dead leaves and plant material that fall into the water. Bacteria and fungi decompose this plant matter and are in turn consumed by zooplankton such as daphnia, copepods and rotifers, or insect larvae such as caddisflies. Frog tadpoles feed on leaves and other plant matter, as well as algae. Salamander larvae are carnivorous and feed on zooplankton until they are large enough to eat aquatic worms, insects, frog tadpoles and even other salamander eggs and larvae. The food web expands to the surrounding ecosystem as turtles, snakes, raccoons, owls, shrews and other organisms visit the pond for a meal or prey on organisms as they emerge from the pond to inhabit the surrounding land.
Vernal pools are important habitats not only for the life cycle of many species, but also to provide water for wildlife and temporary stopping points for traveling amphibians and reptiles. For organisms that depend solely on vernal pools, they may be the only suitable habitat for that organism and perhaps even the whole population of organisms in the area to survive. These organisms are so closely adapted to vernal pool habitats that they return to the same pool year after year to lay eggs. Salamanders and other amphibians return to the same pond from which they hatched to lay their own eggs when they are adults. Destruction of vernal pools by filling in, draining or polluting can seriously impact local populations of these little-known organisms.
Did You Know…
Want to learn more? Join the party! Vernal Poolooza! – March 9 & 23 (5:30-7:30pm)
Join the vernal pool party and see first-hand how these unique habitats team with fascinating life in early spring. This will be our first vernal pool monitoring of the spring. If we are lucky, we will hear the “quacks” of wood frogs. Registration is a must (call 330.569.6003 or email firstname.lastname@example.org) as below-freezing temperatures will postpone the party. Dress warm, wear waterproof boots and pack a flashlight as we hike to some vernal pools to begin our spring monitoring and observe some of the first signs of life in the ponds. Meet at the James H. Barrow Field Station in Hiram Township, located between Hiram and Garrettsville on Wheeler Rd. (between SR 305 and SR 82). The Field Station is managed by Hiram College as a nature preserve for research and education.
An unusual and fascinating vernal pool invertebrate is called the water scorpion. This “stick-bug-like” insect can grow to be about 3 inches in length. It has long narrow legs and a slender body. Despite its name, it does not sting. However, it is predaceous and has a nasty piercing mouthpart to suck the body fluids of tadpoles, salamander larvae or other hapless prey.
The Ohio Environmental Council has established a vernal pool monitoring program to develop a database of information about vernal pools across the state. If you are interested in learning more about the Ohio Environmental Council and their vernal pool monitoring program, visit http://www.theoec.org/WaterVernalPools.htm.
More Nearby Nature
The following Nearby Nature programs are sponsored by the Friends of the Hiram College Field Station. Hiking fee: $6 for non-members or $3 for members. Call 330.569.6003 or email email@example.com to register. Early registration is necessary as space for both hikes is limited.
Liberty Park Lowlands – Sunday, March 4 (11:00am-1:00pm) An extensive landscape mosaic of over 3200 acres is preserved just west of Aurora. Liberty Park, part of the MetroParks Serving Summit County, is a major component of the preserve complex that includes forest, wetlands, lakes, and a large area of impressive sandstone bluffs. The landscape is rich in wildlife and there is evidence that a black bear ranges throughout the complex. The trails will be wet and muddy. Meet at the Liberty Park lowlands parking lot at 3973 East Aurora Rd. Twinsburg (Ohio Rt. 82) between Aurora and Twinsburg.
Liberty Park: Uplands – Sunday, March 11 (11:00am-1:00pm) Explore the brand new Summit County MetroPark trail that winds through part of the extensive sandstone bluffs on the east side of Twinsburg. This surprising natural area is one of the wildest parts of the Akron-Cleveland area. The trail leads to a wetland complex at the base of the bluffs and provides habitat for a variety of wildlife species. Meet at the new parking lot at 9999 Liberty Road in Twinsburg.