Ponds and Lakes
Click on each section to find out about species found in ponds and lakes
Ponds and lakes are relatively large and deep bodies of open water that may be completely surrounded by open grasslands. Ponds and lakes often have areas of floating vegetation, wetlands and riparian areas along their shoreline. They come in all shapes, sizes, and depths, filling the hollows left in the landscape after the ice sheet melted. In the grasslands, they are usually rich in nutrients. These nutrients are washed in with water draining through the glacial till of the surrounding land, and from dead plant material that falls to the bottom of these bodies of water each year.
During hot, dry summers the amount of water evaporating from ponds and lakes is higher than the amount of water added to them from precipitation and water intake. This process leads to a concentration of nutrients. Many grassland ponds have rings of plants, such as alkali saltgrass and foxtail barley, immediately surrounding the lake shore. These plants appear as the water level drops.
There is a lot of activity in ponds and lakes that we can’t see by looking down from the surface. Some grassland ponds and lakes have cattails and bulrushes growing around the edges with their roots in soil under shallow water. Waterlilies grow further out with their roots in water as much as 2.5 meters deep – water that is filled with microscopic algae, tiny snails and other crustaceans, and zooplankton. Further out in deeper water, plants such as greater bladderwort have floating roots that take in nutrients directly from the water. In the deepest part of lakes where light barely penetrates, freshwater clams, worms and insect larvae provide food for any fish in the lake.
These rich grassland ponds and lakes are very important for a large variety of birds, mammals, amphibians and reptiles. Spring comes early to the low elevation grasslands, and thousands of migrating waterfowl flock to the ponds and lakes as soon as there is an opening in the ice. They stay and feed then move north in stages as more ponds and lakes open up. After ice melt, many birds stay all summer to nest and rear their young nearby, and are joined again in the fall by returning birds that nested further north. Barrow’s Goldeneye can be found in large numbers in spring and fall migration, but also during the summer nesting period.
The Yuma Myotis is a common bat species that can be seen flying and feasting on insects over ponds and lakes in the summer. It is not known where these bats spend the winter. Painted Turtles like to sun themselves on floating logs or other debris at the water’s edge in spring and summer, and burrow deep down into the mud of the lake bottom for the winter.
A special feature of grasslands is the many white-edged saline ponds that are adorned with rings of coloured plants all around the edge. The white salt crystals and coloured saline-loving plants are an indication of increased salt concentration, especially sodium bicarbonate and magnesium carbonate. Some of these ponds abound with brine shrimps. Dark red glasswort often forms the outer ring of vegetation, with yellowish alkali saltgrass, which can tolerate more salt and moisture, forming an inner ring.
The soil surrounding these lakes has a high proportion of soluble minerals that are carried into the lake by water flowing under and over the ground. The water in another lake only a short distance away may be quite fresh because the soils in that area don’t have the same high proportion of minerals.
Want to find out more about how water and nutrients cycle through an ecosystem?
Go to Ecosystem Processes
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Other communities in cross section
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