Mequon Nature Preserve: Ephemeral Pond EarthCache
Mequon Nature Preserve: Ephemeral Pond
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An EarthCache adventure is treasure hunting for the caches that the Earth has stored. EarthCache sites do not use stored containers; their treasure is the lessons people learn about our planet when they visit the site. Visitors to EarthCache sites can see how our planet has been shaped by geological processes, how we manage the resources and how scientists gather evidence to learn about the Earth.
Ephemeral ponds are unusual and hard-to-recognize wetlands that are only wet for part of each year. Ephemeral means “lasting a very short time” or “transient.” Because many ephemeral ponds are wet in springtime and dry from mid-summer on, the names “spring pond” and “vernal pond” (vernal meaning “spring”) are also used.
CREATING AN EPHEMERAL POND
Between 25,000 and 10,000 years ago, the most recent glaciers ground across Wisconsin’s landscape and then retreated. These glaciers scoured the earth and left the kettles, ditches, and other low spots that would become the state’s rivers and streams, lakes and ponds – including ephemeral ponds. Southeastern Wisconsin’s landscape contains lots of the rolling topography that favors the formation of such ponds.
FILL 'ER UP
An ephemeral pond gets its water from the rain and snow that falls directly into it or that flows down from surrounding hills. Another source of water is rain that feeds the ephemeral ponds indirectly. Precipitation soaks into the ground, causing the water table (the zone in the soil that is soaked or saturated with water) to rise, and keeping ponds from drying out. Water entering an ephemeral pond does not go deep into the ground because a “hardpan” blocks its path. Hardpan is a layer of clay or minerals that water cannot pass through easily. The hardpan can be a few inches to a few feet below the ground surface.
EMPTY IT OUT
An ephemeral pond has no permanent above-ground outlet. The only way for these ponds to empty is by very slow movement of water through the ground or by evaporation, which can take days, weeks or months depending on the amount of rainfall, the air temperature and the size of the pool. During a series of wet years an ephemeral pond may keep its water, and during a period of drought there may be years when it never gets wet.
NOT EVERY HOLE...
Not every temporary pond qualifies as an ephemeral pond. The plants and animals that depend on ephemeral ponds have developed adaptations and lifestyles that allow them to survive the wet-dry extremes of their environment. Along with the frogs, turtles, and insects that can be found in most wetlands, scientists look for animals that are specially adapted to the wet-dry cycle of an ephemeral pond. Blue-spotted salamanders, wood frogs, and fairy shrimp are a few of the indicators of ephemeral ponds in Wisconsin. They are called obligate or direct indicator species, and they are linked to ephemeral ponds for part or all of their life cycles. Timing is everything, and these species have the ability to compress the amount of time that is needed to grow to adulthood into the period before the pond dries. Ephemeral ponds are also defined by an animal they lack – fish. Their absence as a predator aids in the growth of the amphibious obligate population.
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The coordinates take you to a sign post. The sign post directs you to the ephemeral pond. Then...
YOUR ASSIGNMENT:
To claim a “Found It” for this EarthCache, you must perform the following:
In Your Log -
• Describe the ephemeral pond at the time of your visit. Is there any water in it? Is it muddy? Or is it dry?
• Did you see any obligates? What kind? You can be generic: frog, salamander, etc. You do not need to be specific.
• OPTIONAL - Photographs of the pond and/or any obligates is not required but always appreciated.
Email to the Cache Owner (do not post in your log) –
• If there is water in the pond, measure the length of it using your GPS.
• Is this pond within the woods or outside of them? How do you think this affects the period of time that the pond contains water throughout the year?
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My THANKS go out to the following people for their approval and guidance in setting up this EarthCache at the Mequon Nature Preserve:
Kristin Gies (Director), Jason Nickels (Education and Restoration Manager), Christine Nuernberg (Secretary/Treasurer, Board of Directors), Kate Redmond (Teacher-Naturalist author of the Mequon Nature Preserve Field Guide)
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Additional Hints
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