Tag Archives: moreau lake state park

Lakes Have Seasons, Too

As the northeast transitions from fall to winter, watch for changes in Parks lakes and ponds nearest you.  You might notice that the water churns more than it did during the summer, or you might even notice ice beginning to form at the surface.  Such phenomena can mean exciting happenings deeper in the water.  One of the most fascinating changes to observe is lake-turnover, or the mixing of cool and warm waters.

Lakes that turn over twice a year are known as “dimictic”: di=twice, mictic= mixing.  They are one of the most common types of lakes on Earth.  Dimictic lakes freeze in the winter and melt completely by summer.  These lakes mix during the spring and fall, after ice melts and before ice forms.  Examples of dimictic lakes are seen across New York State, including Shaver Pond in Grafton Lakes State Park, Moreau Lake of Moreau Lake State Park, Lake George of the Adirondack region, and Lake Erie.

combined spring turnover image
Long Pond at Grafton Lakes State Park during spring turnover: ice melting after winter (top), followed by water mixing into the lake (bottom). Fall turnover is the opposite: water mixing followed by ice forming in early winter. Ice photo by OPRHP. Mixing photo cropped from original by L. Schelling, OPRHP.

Without turnover, aquatic life in different areas of a lake may not have enough oxygen or nutrients to thrive.  Calm waters tend to separate into layers – with denser, “heavier” waters sinking below less dense surface waters, creating an invisible boundary through which oxygen and nutrients cannot pass.  Water is most dense 4 degrees Celsius above freezing (4 OC, or 39OF) and becomes less dense as it cools or warms from this point.  In the summer, this means warmer water is at the surface, closer to the air and thus richer in oxygen for fish.  Meanwhile a layer of cooler, 4oC water settles at the bottom – where many nutrients accumulate, but also where decomposition of dead animals and plants can lead to little to no oxygen in the water.

adapted figure of dimictic temperatures
Dimictic lake temperature throughout the seasons, with the layering (“stratification”) and mixing of warmer (red) and cooler (blue) waters. Spring turnover results from ice melting, and fall turnover results from wind chilling and mixing surface waters. Image adapted from Figure 44.10 in “Ecology and the Biosphere” (Candela Learning).

 

As chilly, windy fall weather kicks in, some of the oxygen-rich surface water can cool, sink into the lower levels of the lake, and push the deeper, nutrient-rich waters up closer to the surface.  The result is a well-mixed habitat for fish.  In dimictic lakes, this turnover happens again in the spring, when the surface ice melts to that heavier, 4oC water and mixes into the deeper waters.

Why are some lakes dimictic and others not?  One reason is lake location — dimictic lakes are more common in temperate regions with warm summers and cold winters, where lakes may freeze over completely.  Another factor is lake size.  Two lakes that are famous for not having complete mixing are Round Pond and Green Lake in Green Lakes State Park.  These are the rare “meromictic” (mero=part) lakes which mix in the upper waters but are too deep to allow surface and bottom waters to mix.  Alternatively, some lakes may be so shallow that they mix frequently (“polymictic”). NY Natural Heritage Program describes 7 different types of lakes in the state.

Seasonal turnover is important for lake recreation as well as for fish and plant life within lakes.  Fishing can improve near the end of mixing periods in lakes that experience turnover, since now oxygen and nutrients will be better distributed throughout the water.  Many fish and aquatic life are sensitive to changes in their habitat – oxygen and nutrient levels, as well as temperature changes. Keeping an eye on the changes in the water is useful to biologists and park enjoyers alike.

Post by Erin Lennon, State Parks Water Quality Unit.

Sources and Further Reading

NY Natural Heritage Program Conservation Guide on oligotrophic dimictic lakes

New York Natural Heritage Program’s “Ecological Communities of New York State” 2014 edition describes all of the lake and pond types in the state

Ecology and the Biosphere” from Candela Learning.

Green Lake is a rare meromictic type.

Thermal stratification & the effects of a change in temperature on aquatic organisms.

 

Saratoga Spring

No, I didn’t forget an s.  After months of cold, brown surroundings, the spring season is beginning to breathe new life into our little town.  I’m not talking sundresses and flip-flops just yet.  No, the subtle signs of spring are what you and your kids are after.  Tiny harbingers that chip away at the dirty parking lot snow and melt your wintery heart drip by drip.  This time of year, if you’re watching closely, they seem to appear daily.  There are many family-friendly places for you to visit and experience early spring in the capital region, and we can tell you where to start!

Have you ever driven past a pond on a warm evening in April or May?  The next time you do, roll your windows down.  The chilly breeze will carry a chorus of peepers into your car and surround you with spring.  The tiny animal that makes this huge noise is called a Spring Peeper.  It is a frog the size of a postage stamp!  In Saratoga Spa State Park, the sound of peepers is the first true sign that spring is around the corner.  For a special glimpse of this frog, join Spa Park’s FrogWatch.  On the last Thursday evening of April, a Park Naturalist will guide visitors through a special wetland where they get a chance to hear and see the little frog with a huge voice!

A spring peeper at Wellesley Island State Park. Photo by Julie Lundgren, NYNHP.
A spring peeper at Wellesley Island State Park. Photo by Julie Lundgren, NYNHP.

Another of Saratoga’s spring sounds comes from a sharply dressed male bird called the Red Wing Blackbird.  These birds fly south to escape the snow and ice, but they are one of the first to arrive back from their winter vacation.  Smaller than a crow but just as loud, the blackbirds congregate in tall grasses and proclaim their territory with a raucous “okalacheeee!”.  To hear them yourself, visit Moreau Lake State Park on a sunny day and bring your binoculars to see their wings flash red!

redwingedbb
Photo courtesty of Flickr. https://www.flickr.com/photos/texaseagle/14121019609.

After all of this peeping and proclaiming, perhaps your family would enjoy a quiet walk to enjoy a silent sign of spring.  Visit Saratoga Spa State Park’s Hemlock Trail for a short, flat walk to see the first spring plant, the Skunk Cabbage.  This magenta and green flower unfurls from the swampy sections of Saratoga.  It gets its name from the acrid odor it releases when it is crushed.  Later in the spring, the strange looking flower will be replaced by large, showy green leaves.  To see and smell this plant for yourself, go to the Hemlock Trail entrance on Crescent Avenue in Saratoga Springs.  You’ll find the plants about half way around the mile-long loop.

We hope you enjoy your outings in our state parks, and everywhere spring is sprouting.  Each day of this special season provides a new opportunity for you and your family to explore the outside world!

For more information regarding outings at Saratoga Spa State Park, please call the Environmental Educator at (518) 584-2000 Ext. 116.

Check out these additional spring-themed events that are happening across the state:

Vernal Pool Exploration for Families @ Minnewaska State Park Preserve, April 25

Family Adventure: Night of the Frogs @ Connetquot River State Park Preserve, May 30

Family Fun: Tadpole Expedition @ Caleb Smith State Park Preserve, May 31

Pre-registration is required for most programs.

Post by Alli Schweizer, Saratoga Spa State Park.