We explain what a lake is, how it is formed and classified. Also, what are its main characteristics, flora, fauna and more.
What is a lake?
A lake is a body of water that is separated from the sea and is fed by rivers and streams.. Although it is difficult to establish exactly, it is believed that there are more than two million lakes around the world.
Most lakes are freshwater, although there are exceptions of brackish water lakes, such as the Caspian Sea. Although it is named and known as a sea, the Caspian is actually the largest lake on the planet, with more than 370,000 km2 of surface.
Lakes can be formed by various processes. The most frequent are tectonic origin (formed by movements of tectonic plates), glacial (formed by the melting of glaciers), volcanic (formed in volcanic craters) and artificial (formed by human action).
Although their names sound similar, lakes and lagoons have differences. The most important is its extension: the lakes are larger and deeper, while the lagoons are usually smaller and shallower.
Lake formation
Lakes can be classified, according to their origin, into the following types:
- Tectonic lakes. They are formed when the Earth's crust sinks and this sinkhole slowly fills with water.
- volcanic lakes. They are formed in the crater of a volcano.
- glacial lakes. They are formed by the melting and melting of glaciers.
- Meteorite lakes. They form in craters produced by the impact of a meteorite.
- coastal lakes. They are formed by the accumulation of salt water and fresh water in a depression near the sea.
- artificial lakes. They are formed by human activity, such as the construction of dams or reservoirs for flood control or power generation.
Flora and fauna of the lakes
The biological diversity of lakes depends on their location, the temperature of their waters and the availability of nutrients..
Lake flora typically consists of phytoplankton and submerged plants, as well as riparian species. Phytoplankton, made up of microorganisms capable of photosynthesis, play a fundamental role in the primary production of food and oxygen in lakes. Emergent aquatic plants, such as reeds and lilies, usually grow and develop in coastal areas.
As for fauna, the lakes are home to a variety of species. Aquatic insects, frogs, crabs, fish, birds and some mammals, such as beavers, are common.
Lake pollution
The main causes that explain the pollution of lakes are:
- Chemical pollution. It comes from various sources, such as agriculture, industry, shipping and waste discharge. Some of the most common contaminants include heavy metals, herbicides, and fertilizers.
- Sewage pollution. It comes from direct discharges of household wastewater that are dumped without treatment into the waters of the lakes.
- Plastic pollution. It comes from the dumping of single-use plastics, such as bottles, bags and containers, which accumulate in the waters and on the beaches of lakes, and take thousands of years to degrade.
Tourism and recreation in the lakes
Many times the lakes are used for water sports and as a tourist attraction. The scenic beauty of some of the world's lakes attract millions of tourists who come to enjoy the natural environment and practice sports.
Swimming, sailing, kayaking and water skiing are some of the sports practiced on the lakes. Lake Tahoe (United States), Lake Baikal (Russia) and Lake Como (Italy) are some of the most chosen by tourists in the world.
Larger lakes
The four largest lakes in the world are the following:
- Caspian Sea. Although its name refers to a sea, it is a lake. It has an extension of 371,000 km2. It is located between Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan.
- Lake Superior. It has an extension of 82,000 km2. It is located between the United States and Canada.
- Lake Victoria. It has an extension of 69,482 km2. It is located between Uganda, Tanzania and Kenya.
- Lake Huron. It has an extension of 59,570 km2. It is located between Canada and the United States.
- Lake Michigan. It has an extension of 57,750 km2. It is located in the United States.
References
- Aquae Foundation. (2021). The largest lakes in the world. https://www.fundacionaquae.org/
- GeoEncyclopedia. (2021). Lakes. https://www.geoenciclopedia.com/
- Tarbuck, E. and Lutgens, F. (2005). Earth Sciences. An introduction to physical geology. Pearson Education.
