The Lake in Winter
By David Ernes – Lake Management Committee
A frozen lake is just one more sign that winter has come to Roaming Shores. It presents a frozen snapshot of the beauty of the lake that has an almost alien quality to it. A lake’s “winter” season is not usually associated with December 21st to March 21st, but is often based on the dates that the lake becomes fully ice covered. Once the surface of the lake is frozen, the entire ecosystem under the ice changes to cope with the colder temperatures.
The microscopic animals (zooplankton) and photosynthetic organisms (phytoplankton) produce thick-walled resistant cells, which allows them to survive until spring. Some species of cyanobacteria (blue-green algae) can survive at the cold temperatures by become cannibals and consuming other algae species for food they will not get from the sun. It is unlikely that they will form blooms since the conditions are not ideal, although it is not impossible.
If the algae do not completely become dormant, they may actually produce oxygen, which would be beneficial to the fish, who also share this space under the ice. If not, fish normally seek the warmer waters under the ice and can survive as long as the oxygen levels in the water are adequate. They likely migrate to the sections in the lake that are the deepest, to have the best chances for survival. Since they are not warm blooded, their metabolism slows and their activity level decreases, requiring less energy to survive. This continues until the ice melts and the water starts to warm up again.
Aquatic plants can actually handle the winter better than their terrestrial cousins if they are protected under the water. The main body of the plant dies, but the roots can survive. Some will form nodules, which can store energy while they wait for the sun to reappear. However, if they are exposed to the cold air, they may dry out and even the roots can then freeze. Lakes who perform a winter drawdown use this behavior as a method to reduce nuisance plants.
The most important aspect of the lake in winter is ice thickness. Remember, it may look solid, but with 450 acres of surface area, conditions may differ from one location to another. Some residents may use “ice cutters”, resulting in open water even if the rest of the lake is frozen. If you do venture out on the ice, use extreme caution and don’t do it alone.
(Some information presented in this article was extracted from Lakeline Vol 34, #4 (2014))
BE LAKE RESPONSIBLE And HAVE A HAPPY HOLIDAY SEASON
History of Concerns About Water Quality, Erosion, or Dam Safety 1966-2016
RRA Member Carolyn Tharp compiled a report on lake management to highlight moments during the first 50 years of The Shores when lake management and concerns were mentioned. This report was approved to be posted here on the website at the Sept 5th meeting of the Board of Directors. It is linked below and is also listed under LMC Reports on our Lake Management pages.
Bryozoans or Frog Eggs?!
by R.D. Gainar, CEBS – Lake Management Committee
Several residents have asked me “What were those strange, jelly-like, blobs stuck to my dock this summer that look sort of like frog eggs?” They are actually aquatic animals known as bryozones, a name that literally means “moss animal”. Bryozoans are fairly common in lakes and streams and form colonies of gelatinous mass attached to submerged tree branches, docks, pilings, etc. Each colony, sometimes growing to the size of a soccer ball, is made of many individual creatures called “zooids” which are microscopic creatures with a mouth, digestive tract, muscles, and nerve centers.
Freshwater bryozoans are harmless, though they occasionally clog water pipes and sewage treatment equipment. Bryozoans eat microscopic organisms and are eaten by several larger aquatic predators, including fish and insects. Snails graze on them, too. Like mussels and other filter feeders, bryozoans gradually cleanse the water as they feed. The good news is that their presence usually indicates good water quality.
Bryozoans are filter feeders, sucking algae, bacteria (both good and bad), and decaying organic material out of the water, which benefits water quality. The bryozoans that are so visible in summer will disappear as fall progresses. At that point, they produce survival pods that contain a single zooid. Zooids in the pods can survive long periods of dormancy, including drying out and freezing. They start reproducing new colonies if and when the conditions are right.
They’re weird, and not the prettiest of things, but do these bryozoans mean any harm? The simple answer is no. Bryozoans are beneficially removing unwanted organisms from the water, so elimination of them would likely be detrimental to the aquatic environment. I generally leave the colony to do its thing. However, if you just can’t stand to look at it or if they frighten your guests when showing off our lake, manual removal is probably the best solution.
The good news is that if these guys thrive in our lake, it’s a good indication that we have a healthy, organic lake environment. For more information about bryozoans see http://mdc.mo.gov/discover-nature/field-guide/bryozoans-moss-animals. Love the Lake!
Lake Turnover – A Fall Classic
By David Ernes – Lake Management Committee
In the fall, the kids go back to school, football returns, and we wonder when the Browns will win again. Another sign of fall is the lake turnover. It is a normal occurrence for a lake like ours that is fairly deep. The lake, during the summer, is much cooler at the bottom than at the top, where it is heated by the sun. The cooler water is more dense, and stays at the bottom. Because of this stratification or “layering”, the normal action of the wind does not mix the layers. Think of the lake as a black and tan beer – the more dense pale ale at the bottom and the less dense stout at the top. The layers tend to stay separated even as you drink it.
Now, as we go into fall, the temperature of the surface water decreases, and the density increases. It slowly starts to approach the density and temperature at the bottom. As the temperature difference between the layers decreases, the lake is more easily mixed by wind. This mixing takes place often around the last two weeks of October. A number of things happen – the lake is no longer stratified, and the materials at the bottom of the lake can now reach the surface. Since the nutrient levels at the bottom of the lake are higher than at the surface, this can sometimes (but not always) result in an algae bloom. You may also notice a slight sulfur odor as other materials at the bottom make it to the top. This usually ends after a few days.
After the turnover, the surface water continues to cool. Once it reaches 39 degrees, something very interesting happens – the density of water starts to decreases. This is why ice floats on water and deeper lakes will likely never completely freeze. The ice and colder water forms a blanket on the surface of the lake, so the main body of water never drops below 39 degrees. This is beneficial, as the fish do not end up as frozen fish sticks. A similar turnover occurs in the spring as the surface warms.
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