The Ephemeral Pond at Riveredge
In Wisconsin, United States
Size:  (not chosen)
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The Ephemeral Pond at Riveredge
Grab a map from inside the Nature Center or from the outside stand. Follow the trails to the Vernal Pond marked on the map. It is a long hike (about 0.4 miles to the pond), so make sure you have a map (and a compass wouldn’t be a bad idea). This is a State Natural Area and requires sensitivity. STAY ON THE TRAILS AT ALL TIMES!
In order to get credit for this cache, you must complete the following tasks:
1. EMAIL the following answers to owner:
a. What is the current water depth? (From the boardwalk, read the measurement of the water depth stick)
b. Is there an open canopy or closed canopy over the pond? How does that affect this pond?
c. What makes an ephemeral pond different than other depressions that fill up with water in spring?
2. POST in your log:
a. Describe the vernal pond at the time of your visit. Was there any water? Did you see any obligate species?
b. (OPTIONAL) Take a picture of the vernal pond (along with you and/or your GPSr) either from the boardwalk or from the overlook of the pond.
The Ephemeral Pond at Riveredge
What is an ephemeral pond?
Ephemeral ponds, also known as vernal pools or seasonal ponds, are basins or depressions with impeded drainage that temporarily hold water after the winter snow melts and spring rains begin. By mid-summer, these ponds almost always dry up completely.
Many factors are involved in the formation and preservation of ephemeral ponds. The small depressions are typically the result of glacial sculpting activity. Over years, woodlands formed, creating an isolated environment. The underlying layer of the earth is generally an impermeable layer of silt loam, clay, or bedrock, which prevents fast absorption or drainage. The length of time these pools hold water depends on a variety of factors, including the amount of spring rainfall, depth of the land depression, and the rate of evaporation. Pools with a closed canopy (heavy tree cover) may delay the warming of the pool and slow evaporation. Pools with an open canopy will allow for faster warming which could speed up evaporation. The biology of the pool is controlled by water depth, temperature, pH, pollution, duration of water in pool, and other conditions.
Example of ephemeral pond in spring vs summer:
Example of closed vs open canopy over ephemeral pond:
Why are ephemeral ponds important?
Ephemeral ponds are critical to the ecological biodiversity of the landscape by preserving certain animal and plant species. Because these ponds dry up in summer, they contain NO FISH! This is especially important for the breeding of amphibians and certain invertebrates who can lay their eggs when the pool contains water in spring without worry of being eaten by fish, and then develop in the dry habitat in summer.
Many species rely on vernal pools as a water or food source. Common wetland plants found at the pool include yellow water crowfoot, mermaid weed, Canada bluejoint grass, floating manna grass, spotted cowbane, smartweeds, orange jewelweed, and sedges. Besides providing a necessary breeding habitat for amphibians, these plants also provide a feeding, resting and breeding habitat for some birds, and a source of food for many mammals.
Not all pools of water that dry up in summer are considered ephemeral ponds. They must contain an active population of species that require the pond for survival (also called obligate species) which are noticed year after year. Many of these ponds are disappearing due to deforestation, pollution, and other factors of environmental impact. Because obligate species depend on these ponds, conservation of these habitats is critical.
What animals rely on ephemeral ponds?
Note: Without a continuing and sustainable community of one or more of the following animals, a pond is NOT considered an ephemeral 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.
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. Breeding evidence would be a breeding congress, spermatophores, egg masses or larvae.
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.
Permission to place this cache granted by Marc White, Director of Research, Stewardship and Adult Education at Riveredge Nature Center. Approval for State Natural Area cache placement granted by Thomas Meyer, Conservation Biologist of the WDNR Bureau of Endangered Resources, State Natural Areas Program.
Riveredge Nature Center is a 350-acre natural sanctuary along the Milwaukee River of both forest and prairie and includes 10 ponds, 65 butterfly and skipper species, 192 bird species, and 664 species of plants. It has 10 miles of hiking trails, 7 miles of cross-country ski trails, and 1.5 miles of snowshoe trails. There are multiple scenic overlooks, and it features a Vernal Pond. If you have time to check out the Nature Center , I'd recommend it. It's great for kids! The trails are open from dawn to dusk and open in winter for skiing or snowshoeing. A small trail fee may be required. Dogs are not allowed.
The Riveredge Ephemeral Pond is designated a State Natural Area and part of an ongoing monitoring program with WEPP (Wisconsin Ephemeral Pond Project). Citizen volunteers may train to help describe and monitor the ecology of the pond habitat by learning water quality sampling techniques, hydrologic monitoring, amphibian & aquatic invertebrate sampling and identification, and site location and delineation using handheld GPS receivers. Contact Riveredge if you are interested in becoming a volunteer.
1. The Vernal Pool Association Website (http://www.vernalpool.org/vernal_1.htm)
2. Wisconsin DNR Website http://dnr.wi.gov/ORG/LAND/ER/communities/index.asp?mode=detail&Code=CLEPH390WI
3. Riveredge Nature Center http://www.riveredge.us
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Last Updated: on 7/1/2014 7:18:07 AM Pacific Daylight Time (2:18 PM GMT)
Coordinates are in the WGS84 datum