Tag Archives: Lake Erie

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, OPRHP Water Quality Unit.

Sources and Further Reading

NY Natural Heritage Program Conservation Guide on oligotrophic dimictic lakes http://acris.nynhp.org/guide.php?id=9880

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

http://www.dec.ny.gov/docs/wildlife_pdf/ecocomm2014.pdf.

“Ecology and the Biosphere” from Candela Learning.  https://courses.candelalearning.com/biologymajors/chapter/chapter-44-ecology-and-the-biosphere/

Green Lake is a rare meromictic type. http://www.dec.ny.gov/outdoor/70328.html

Thermal stratification & the effects of a change in temperature on aquatic organisms.  http://www.lakeaccess.org/russ/temperature.htm

 

Sand: The Beaches’ Hidden Treasures

Fourth of July is nearly upon us and it is time to hit the beach!  And beaches mean sand – sand to build sand castles, sand that tickles your toes during beach strolls, and sand for beach volleyball and bocce.

But what is beach sand?  According to http://www.merriam-webster.com, sand is “a loose granular material that results from the disintegration of rocks, consists of particles smaller than gravel but coarser than silt.”  These small particles are less than 1/10th of an inch in diameter.  The mineral makeup of individual sand particles depends on local and regional rocks, which are eroded by ice and rain, then carried to the ocean by rivers where they are deposited on gently sloping beaches. The size of individual sand particles is dependent on the slope of the beach, both above and below waterline. The color of beach sand is influenced by nearby landscapes and ocean bottom.

In New York, many beaches have a variety of minerals including quartz, white or clear particles; feldspar, buff-colored particles; and magnetite, black particles.  On beaches around the world you will find lava (black beaches), coral (pink beaches), garnet (purple beaches), olivine crystals (green beaches) and more. Some beaches have unique sand such as the orange Kerala coast beach sand in India.

New York State Parks have over 65 beaches on lakes, ponds, rivers, bays, and the Atlantic Ocean.  Let’s take a closer look at the sands on a few of those beaches …

Along Lake Erie

Evangola Beach Sand

The sand on the beach at Evangola State Park in southern Erie County is principally quartz, feldspar, magnetite, with smaller amounts of garnet, calcite, ilmenite, and hornblende.  All of the particles are approximately the same size.

Along Lake Ontario

Hamlin_Beach Sand

Located northwest of Rochester, Hamlin Beach State Park beach sands are mostly quartz, hypersthene (brown and gray), and augite (greenish).

On Long Island

Jones_Beach Sand A

Jones Beach State Park has 6-1/2 miles of Atlantic Ocean shoreline; different sections of beach have slightly different sands.  Some parts of the beach have sand that is mostly comprised of quartz with a little feldspar and tiny shell fragments.  Note that the clear quartz particles have different sizes.

Jones_Beach Sand B

 

 

 

 

 

 

 

 

Other sections of beach at Jones Beach State Park have quartz, garnet, and magnetite sand with a few tiny shell fragments. All of the particles are about the same size.

Robert_Moses Sand

 

 

 

 

 

 

 

 

The beach at Robert Moses State Park, also on the Atlantic Ocean side, is mixture of quartz, garnet, magnetite, and shells. The shell in the photo is about 1/3” long; larger glass piece is about 1/6” long.

Napeague_Beach Sand

The beaches on the north side of Napeague State Park and Hither Hills State Park are along Napeague Bay. Here the sands contain magnetite and garnet which give the sand a purplish hue.

Bring your magnifying glass the next time you head to a NYS Parks beach.  You might be surprised at what you see when you take an up-close look at the sand.

Thanks for Anne McIntyre, Dave McQuay, and Megan Philips for their help with collecting sand samples for this article.

Post and sand photos by Susan Carver, OPRHP.

Learn more at:

Coastal Care: http://coastalcare.org/2010/10/dream-in-color-on-the-worlds-rainbow-beaches/

International Sand Collector’s Society: http://www.sandcollectors.org/SANDMAN/The_Hobby_of_x.html

Sand Atlas: http://www.sandatlas.org/sand-types/

Pilkey, Orrin H., William J Neal, Joseph T. Kelley, & J. Andrew G. Cooper; The World’s Beaches : A Global Guide to the Science of the Shoreline; University of California Press, Berkeley, 2011.

 

Ice Volcanoes

Ice volcanoes erupt at Evangola State Park, by Dave McQuay
Ice volcanoes erupt at Evangola State Park, by Dave McQuay
Trekking towards Lake Erie at Evangola State Park, by Dave McQuay
Trekking towards Lake Erie at Evangola State Park, by Dave McQuay

 

 

 

 

 

 

 

The turn to chillier temperatures reminds us all that there’s so much to look forward to in the wintertime at New York State Parks. One of our favorite winter phenomena are the ice volcanoes that form along the eastern end of Lake Erie shoreline. During cold weather, waves splash against the shore where the spray and slush form cone-shaped ice sculptures. In the middle of the cone is an open vent. As long as Lake Erie has open water, the waves roll under the ice volcanoes and are channeled through the vents. Water explodes into the sky as much as 30 feet high, increasing the height of the ice cone. When Lake Erie freezes over the ice volcano vents freeze shut and they become “inactive ice volcanoes.” At Evangola State Park, naturalists lead school and public groups to see the amazing ice volcanoes and ice sculptures that are a rare phenomenon found only on a few of the Great Lakes.

featured image is of park patrons in an ice cave, another unusual ice formation along the Lake Erie shoreline at Evangola State Park, photos and post by Dave McQuay.