The Western Pennsylvania Conservancy: Saving the Places We Care About™

WPC: A Lifeguard for Seasonal Pools

Western Pennsylvania Conservancy (WPC) has received a State Wildlife Grant to develop a seasonal pools registry and research these wetlands. The project will involve partnering with scientists from academic institutions, non-profit organizations, state and federal agencies and public volunteers to identify, locate and study seasonal pools in Pennsylvania. The information will be used as a baseline for future inventory, studies and regulatory considerations.

Visit the seasonal pool website.

This work will complement the on-going studies being conducted through the Pennsylvania Natural Heritage Program by biologists with WPC and The Nature Conservancy. This data will allow us to develop future studies of plants and animals using these habitats, obtain a greater understanding of regional variations and rarity and drive conservation efforts for these important wetlands.

Individuals or groups interested in volunteering in this effort should contact Ephraim Zimmerman at ezimmerman@paconserve.org or by phone at 412-586-2334.

There are generally two types of seasonal pools in our state. The most familiar are vernal pools, which hold water from late winter into summer. Many hikers and fishermen have encountered vernal pools in spring, attracted by the odd quack-like calling of wood frogs. The other type is the autumnal pool, which are filled from late autumn to mid-summer. The distinction in seasonality affects the timing of breeding among pond animals and the growth and flowering of plants.

Seasonal Wetlands - Appraising Our Overlooked Treasures

When we think of wetlands, we envision places like Conneaut Marsh and Black Jack Swamp in the northwest part of Pennsylvania or the big bogs and marshes at Canaan Valley in West Virginia. These places represent our image of a wetland because we see standing water any time we visit, in all seasons of the year. Typical wetland wildlife lives there and leaves familiar signs. Beavers build dams from red osier dogwood and willow, and muskrats construct their huts of cattail. Herons hunt in the shallows and waterfowl rest on open water.

Most of us, though, don’t realize that we are surrounded by many smaller wetlands. While less spectacular than the big marshes and swamps, they are no less important. Some of these smaller wetlands are known as seasonal pools, often overlooked because they are wet for only part of the year.

Seasonal pools are the domains of amphibians. Because the pools go dry for much of the year they cannot support fish. Salamanders assume the role of top vertebrate predator. In our region, the mole salamanders, family Ambystomatidae, are the most prominent group of salamanders that use seasonal pools for breeding. The earliest to breed is the Jefferson salamanders. Later in the season, spotted salamander, marbled salamander, red-spotted newt, wood frog and green frog all use the same pools to breed and lay their eggs.

Even seasonal pools have food chains and these unique habitats provide lodging for an interesting mix of invertebrates. Fairy shrimp are tiny crustaceans that live in these seasonal wetlands and nowhere else. It is believed that the drying period followed by a wet interval trigger their eggs to hatch. Other interesting invertebrates of seasonal pools include limnephilid caddisflies (which build tube casings out of bits of shredded leaves and plants), mosquitoes, phantom midges (which appear to be almost transparent as larvae), damselflies, dragonflies and a variety of beetles. A well-known seasonal pool beetle is the predacious diving beetle, which traps air bubbles to breath when hunting underwater.

A seasonal pool at Scotia Barrens (State Game Lands No. 176) just west of State College in Centre County. Unlike more familiar wetlands, which are influenced by groundwater and surface streams, seasonal wetlands receive their water from precipitation and runoff. Typically, these pools hold water during one or two seasons and are dry the rest of the year. In times of drought they may stay dry throughout the year. Seasonal pools provide critical habitat for specific guilds of plant and animal species adapted to seasonal periods of wet and dry.