Lake Learning Articles
Educational
articles put together by Moriya Rufer, PGOLID Water Resource
Coordinator.
We are now near to the summer season on our lakes again. This marks the fourth installment of my lake stratification (layers) and mixing articles. Once the ice melts off the lake, the lake goes through another period of mixing like it did back in the fall.
After this unusually cold winter and blizzards the past couple weekends, I think we're all ready for the ice to come off the lakes! The last couple weeks we've been in that in-between time when we can't start boating on the lakes because the ice is still on them, but the ice isn't safe to walk on anymore.
Whenever I tell people I'm a lake ecologist,
their first question is usually, "So how
are the lakes in the
There's still time to clean up ice litter
Imagine yourself in a month when the ice goes out. You're so excited to get your boat in the water and just go for a ride. As you're flying along the lake with the wind in your hair all the sudden you hit a couple 2x4 boards floating on the lake's surface. On another nice April day, you're walking along the lake and see plastic bags, cigarette butts and aluminum cans washing up on shore. What a way to kill the mood!
The dock issue, dissected and explained
Not much can top the feeling of sitting on a dock to watch the sunset, feeling the cool breeze on your face, or jumping off the end of the dock on a hot day to be refreshed in the lake. We Minnesotans love our docks, and no one will take that away from us. But how much dock do we really need?
What is all this talk and controversy about docks and dock platforms? This issue has been at the forefront of lake issues this winter, as the DNR is sorting out dock regulations.
Today I will talk about how this all started, why dock platforms are an issue, what the potential impacts on lakes are, and the current standing of this issue.
The tremendous power of lake ice
Ice is a marvelous form of our most precious resource. We depend on it for winter fun, and our lakes depend on it for their natural seasonal cycles. Despite the joy we get from frozen lakes in the winter, the ice can also wreak havoc on lakeshore by pushing up the sand and soil into large ridges.
Global warming translates to shorter lake ice cover
Many of us northern Minnesotans enjoy winter on the lakes as much as summer. There are so many possible activities such as ice-fishing, snowmobiling, cross country skiing and snowshoeing. So how will we react when the duration of ice cover on our lakes declines due to global warming? In addition, how will a shorter ice cover affect our lakes and their fish communities?
Did you know that algae are alive under lake ice in the winter? If you enjoy ice fishing, you have maybe seen this occur.
Some species of algae are adapted to survive in cold temperatures, such as the 39º F water under the ice. The growth of these winter algae mainly depends on how much light and nutrients are available to them.
Water
under the ice: winter layers and oxygen levels
We've actually had a real
Hold the salt for the sake our lakes
Get out the shovels and snowblowers!
Most of
How Frogs, Turtles
and Insects survive winter
This week the temperature plunged and our lakes froze over pretty
quickly. We humans
retreated into the shelter of our heated homes and warm coats.
The only animals you see
outside now are warm-blooded animals such as rabbits, deer and
squirrels. So what
happens to the cold-blooded animals like aquatic insects, frogs and
turtles when the lakes freeze?
Keeping our drinking water safe
We are considered the blue planet, yet most of that water is unusable for human drinking and washing. Water covers over 71% of the earth's surface, however less than 3% of the earth's water is freshwater. The oceans make up 97.6% of the earth's water supply, 2% is frozen in glaciers and polar ice leaving 0.4% of the earth's water supply in lakes, rivers, atmospheric water vapor and groundwater combined. That doesn't leave much water for drinking!
When and how do lakes freeze over?
Now that it's too cold to swim in our lakes, we can look forward to the next great lake season – winter sports! Bring on the cold and snow so we can ski, skate, snowshoe, ice fish and snowmobile.
Where does my lake water come from?
All water on the globe whether in the atmosphere (clouds), on the ground (rivers, lakes, ocean), or under the ground (ground water) is ultimately connected. These different groups of connected water can be broken down into smaller and smaller divisions that are more intimately connected.
The temperature has cooled lately and the wind has picked up. These are the ingredients needed for fall turnover in our lakes. A couple months ago (July 29, DL Tribune) I wrote about how the lakes separated into layers in the summer, which is called stratification. To recap, the layering of lakes has to do with the relationship between water density and temperature.
Abundant Fall Bugs – Lady beetles and Bees
Have you noticed there seems to be a lot more lady beetles (also known as ladybugs) and bees out lately? This is a common occurrence on sunny fall days. Today I'll explain why they are out in such numbers at this time of year, and what you can do to avoid them.
Signs of fall – falling leaves and American coots
It's hard to ignore that summer is over and the signs of fall are here. It has been a beautiful week though; the leaves have turned and fallen, and it's time to rake our yards. Also, on most of the area lakes there are tight clusters of small black duck-like birds with white beaks. These birds are the American Coot (Fulica americana) and are not actually ducks but are a type of marsh birds from the rail family.
Aliens are invading our lakes, the sequel! A while ago, I wrote about aquatic invasive plants (7/15/07 Detroit Lakes Tribune). Today, I will cover some common aquatic invasive animals, why they are harmful to our lakes, what the status is in this area and what you can do to protect our lakes.
The Aquatic Food Web: Who's eating whom?
Those of you who fish, probably already know a lot about the aquatic food web without realizing it. The aquatic food web is a conceptual way to look at who is eating who and what in a lake. The reason biologists use the term "food web" now instead of "food chain" is because it is a better way to visualize that everything is interrelated in a lake.
Shallow Lakes: an important yet vulnerable habitat
Over the summer I have touched on the concept of shallow lakes in other columns, but this week I will focus on them. Shallow lakes behave differently and have different dynamics than deep lakes. Before we go any further, let's define "shallow". Shallow lakes are lakes where the sunlight can reach the bottom. Generally, this corresponds to 10-15 feet deep or less. Since the sunlight can reach the bottom, plants are able to grow there.
In Minnesota, our lakes are one of our most precious resources. Even our slogan, "The Land of 10,000 Lakes" boasts of our pride in our lakes. Not much can top the feeling of watching the sun set over the water, swimming on a hot, humid August day, or catching a big walleye. It would be hard to imagine a future without being able to enjoy these activities.
When you have leftover pharmaceutical products such as prescription drugs, over-the-counter drugs, veterinary drugs and vitamins what do you do with it? Traditionally, we were advised to flush it down the toilet or drain. This method of disposal prevents other people from accidentally ingesting the medication; however, it sends this medication into our wastewater treatment facilities. Recent research has shown that wastewater treatment plants and septic systems only partially remove pharmaceuticals, so these chemicals end up in rivers and streams.
Have you noticed that each week it seems like there's a different large swarm of bugs by the lake? One week it's dragonflies, one week it's mayflies, one week it's midges, and so on. The swarms are massive, and then a few days later they're all dead on the ground. These are aquatic insects that actually emerge out of the lake. Aquatic insects are insects that live in a lake or stream for some part of their life.
Water transparency translates to lake condition
Did you know that the easiest, most inexpensive way to monitor water quality in a lake is with a simple white disk? This measurement tool is called a Secchi disk. It is a metal disk, 8 inches in diameter that has a cord attached to the middle. This cord has 6 inch increments marked on it. Each foot is marked in black, while each half foot is marked in red. The way to take a Secchi disk reading is to lower the disk on the cord into the water until you can't see it anymore. Then, you slowly pull it back up until you see it again. You average these two depths from the surface of the water to the disk and that is called the Secchi depth.
Right now, lakes are like layer cakes
Have you noticed lately while swimming that the surface water in the lake is very warm and deeper water is cooler? At this time in the summer, the lakes are separated into vertical layers like a cake; limnologists call this phenomenon stratification. Stratification is a major reason our Minnesota lakes behave the way they do. To understand lake stratification, we first must address the relationship between water density and temperature. Water is unique in that it is denser as a liquid than a solid; therefore, ice floats. If ice sank, our lakes would behave much differently in the winter!
Green aliens are invading our lakes! These aliens are not from a different planet, but from different continents, mainly Eurasia. Today I will talk about some common aquatic invasive plants, why they are harmful to our lakes, what the status is in this area and what you can do to protect our lakes.
Lakes contain various algae and scums throughout the year, so how do you know which are natural and which can cause harm to humans or to the lake? Today, I'll describe some of the most common substances that lake users will come across.
Have you ever wondered why Minnesota has so many lakes, how these lakes formed, which are the deepest and what are the most common names? If so, then read on!
Maintaining healthy habitat and healthy lakes
With over 10,000 lakes in Minnesota, that's a lot of miles of shoreline! There are many things you can do to make your shoreline both beautiful and functional for maintaining water quality and healthy habitat in our lakes.
Introducing a new column about Lakes and Water Quality
The lakes season has returned! I couldn't contain my excitement as the ice receded last week. My husband and I moved to Detroit Lakes from Minneapolis last fall, and since then I have been dreaming about sunsets over the lake, catching walleyes, zipping across the water in the boat and stopping to take a refreshing swim. On a 90 degree day in downtown Minneapolis there isn't much to do, but up here, we celebrate!
Minnesota fish, good for you in moderation
There's nothing quite like a sunny day on the lake when the fish are biting. When you add in an evening fish fry of the catch of the day, it's a perfect Minnesota summer night.
Spring is here and the insects are back. I bet when you hear the word "flies" it triggers negative feelings. Today, I'm going to explain the difference between two types of flies that look very similar to each other but are actually very different: midges (Chironomidae) and mosquitoes (Culicidae).
Boats impact the littoral zone
Now that it's June, the true boating season has begun. While you're out enjoying the lake this summer, there are a few concepts that will help you become a more informed boater and lake steward.
Last week I talked about the trophic state index, which I defined as a continuum in lake phosphorus and algal concentration with an assigned number between 0-100. Trophic states are divisions of that continuum. We classify lakes and give names to the different lake types so they can be easily referred to.
What is Trophic State Index (TSI)?
On April 25, there was an article published in the Becker County Record about county septic inspections for systems over 10 years old. "The lakes to be targeted are those that have been monitored for transparency, chlorophyll-a and total phosphorus and score over 50 on the trophic index."