Focusing On The Conservation of Ecosystems, Habitats & Wildlife

Ponds and Lakes


FYA: For Your Awareness

Ponds and Lakes only cover about 2% of the earth’s surface but contain most of the world’s freshwater supply.

Lake Baikal, in central Asia, is the largest lake on Earth; it contains about one fifth of the Earth’s freshwater and has a maximum depth of 5,315 feet.

What are Ponds and Lakes?

Ponds and lakes are bodies of fresh water (less than 1% saline content) surrounded by land, they can be small to very large like the Great Lakes in the United States and are often slow moving or still. Lakes are often connected to other fresh water sources such as streams and rivers. Lakes can be the source of rivers, many of the biggest rivers begin from lakes but rivers can also flow into lakes. Ponds and lakes are scattered throughout the earth and can be either temporary and seasonal or lasting hundreds of years. Many lakes date were formed in the depressions left by glaciers.

Ponds tend to be shallow and support rooted plants, they often have a muddy bottom and water temperature is fairly uniform. In winter they sometimes freeze over. Lakes can be very deep and can even experience waves. It is too deep for rooted plants except near the near the shore.

Light and temperature are key factors in determining many characteristics of ponds and lakes. Sunlight is diffused as it passes through the surface of the water and the water itself. It is affected by season, time of day, weather and latitude. The clarity of the water is influenced by particulates, like algae and concentration of organic matter. Water temperature is influenced by light and wind and varies seasonally and at various depths depending on proximity to the surface.

Lakes have three distinct stratification layers. Epilmnion is the shallowest layer and is warmest. The middle layer, metalimnion is prone to rapid temperature changes. The deepest layer is the hypolimnion and experiences the coldest temperatures. In the summer lakes can experience large temperature variations while there is usually less variation in the winter, this can result in ice forming on the top layer of a lake. It is during the spring and fall seasons when winds stir up the top and bottom layers of water causing a more uniform temperature which also serves to spread oxygen. Some lakes mix continuously while others mix once each year.

The chemical composition of ponds and lakes is controlled by a variety of factors such as oxygen concentration, nutrient composition and the ph. Oxygen has to be regenerated since it is lost during breathing of living creatures. It can be generated from photosynthesis, and mixing of oxygen rich surface water with those at deeper depths. Important nutrients are nitrogen and phosphorous which are required for the growth of plants. The acidity or alkalinity (ph) of a lake also determines which plants and animals can live in the water. Most lakes have a ph of 4-9, while distilled water is a 7. If water has too low of a ph (too acidic) there are many organisms that can’t sustain life.

Ponds and lakes typically have four zones:                                            Littoral, Limnetic, Profundal, and Benthic.

Littoral Zone is located closest to the shore and includes the high water mark and the intertidal zone, sunlight penetrates this layer where the most plant and animal diversity is found. Living organisms found in the littoral zone can include algae, aquatic plants, snails, clams, insects, crustaceans, fishes, and amphibians. The vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks.

Limnetic Zone is located away from the shore and is well lit. It contains lots of plankton which are small organisms that play a crucial role in the food chain. They are a food source for smaller organisms which are consumed by larger aquatic species, which are eaten by fish. Aquatic plants, plankton, crustacean, and fish live in this part of a lake. The majority of photosynthesis takes place here and this zone is a source for both oxygen and food for the inhabitants of the lake.

Profundal Zone is the deepest part of the lake, where it is coldest and most dense. There is less light that penetrates the surface creating a very different habitat from the other zones in the lake. Species that have adapted to this area require less light and are at home in cold temperatures.

Benthic Zone is the bottom of the lake, often the sediment or mud layer. Animals that live here stay close to the bottom, in some cases attaching themselves to the floor. Crustaceans are often found in this zone.

Where are Ponds and Lakes located?

Ponds and lakes are located on nearly every continent on earth and can be in mountainous regions, valleys, and everything in between. Many are found in mountainous regions. Some are temporary, forming from excess water during rainfall or snowmelt while others are permanent and have existed for hundreds of years.

Why are Ponds and Lakes important to protect?

Ponds and lakes are important to protect for many reasons. They serve as a source for drinking water, a water supply for agricultural crops, and as a source of hydropower for electricity. Ponds and lakes are habitats to fish, birds, plants and wildlife and they serve as places for recreation including swimming, boating, fishing, and nature viewing. Ponds and lakes also provide support for ground water recharge, soil formation, biodiversity, and flood protection.

Why are the threats to Ponds and Lakes?

Ponds and lakes are threatened by many things including storm water runoff, pollutants and pesticides, hydrocarbons, invasive species, and climate change. Storm water runoff collects chemicals, pesticide, and petrochemicals dumping into ponds and lakes, altering ph balance and bringing toxins that call kill fish and other living organisms. Similarly pesticides and other chemicals used in the growth of crops can find its way into ponds and lakes killing fish and altering the balance of this freshwater eco system. Hydrocarbons including gas and oil from motor vehicles (boats), oil spills, leaks and runoff from washing cars can be toxic to plants, animals and humans. Aquatic invasive species can attach themselves to the bottom of boats or animals and disrupt the existing ecosystem. If the invasive species overpopulates it can choke out the native species consuming all of the available food sources. This can result in murky and smelly water and alter the quality of the drinking water.

Climate change affects the quantity of water that feeds a pond or lake. A warming of temperature can impact the species living in the lake causing an imbalance such as algae to overwhelm the other species. It can cause the water to become cloudy, and can also increase evaporation. If the temperatures remain elevated for long periods of time cold water species may relocate or die. Warmer temperatures also cause an increase in UV radiation which also threatens ponds and lakes by killing off species.

Who is protecting Ponds and Lakes?

World Wildlife Federation is working on many levels to protect the world’s fresh water supplies by providing water stewardship education working with governments, businesses and investors to better understand the importance of protecting water resources. They are also working to create greater water security and encourage sustainability in how water is procured for human use and in protecting the natural habitat.

The Nature Conservancy is the 3rd largest private landholder in the United Stations and is the steward of over 120 million acres of land globally which they are using to protect and preserve our water supply and the ecosystems. The Nature Conservancy is currently working on 100 water projects in 35 countries. The Great Lakes Project is one of many projects that the Conservancy is working to protect.  Dive in here to learn more about why it’s so critical to protect our fresh water sources now. 

What can we do to protect Ponds and Lakes?

There are so many ways to protect ponds and lakes. Conserving water is really important and not just in taking shorter showers or not leaving the water faucet running when washing dishes or brushing teeth. For an illuminating look at the amount of water that goes into producing a pair of jeans, a hamburger or chicken dinner, visit Liquid Courage a narrative about the hidden amounts of water that go into producing readily available items that we may be completely unaware, produced by The Nature Conservancy.

Always choose environmentally friendly chemicals, fertilizers and pesticides. Ask yourself if you would want that in your drinking water. Don’t dump paint, solvents or other products down the drain. Fix oil leaks in your car and dispose of vehicle fluids at designated places. Wash your car at a commercial car wash instead of on the street. Rain can wash these pollutants into storm drains and eventually it ends up in our water supply. When removing a boat from the water allow it to dry before moving it to another body of water. Ride a bike, use public transportation, walk, or carpool whenever possible. And volunteer with a community group that protects ponds and lakes.