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A pond is an area filled with water, either natural or
artificial Artificiality (the state of being artificial or man-made) is the state of being the product of intentional human manufacture, rather than occurring nature, naturally through processes not involving or requiring human activity. Connotations Artific ...
, that is smaller than a
lake A lake is an area filled with water, localized in a basin, surrounded by land Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable ove ...

lake
. Ponds are small bodies of freshwater with shallow and still water,
marsh A marsh is a wetland A wetland is a distinct ecosystem that is flooded by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevail ...

marsh
, and
aquatic plants Aquatic plants are plants that have adapted to living in aquatic environments (seawater, saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a pl ...

aquatic plants
.Clegg, J. (1986). Observer's Book of Pond Life. Frederick Warne, London Ponds can be created by a wide variety of natural processes (e.g. on
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows int ...
s as cutoff
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

river
channels, by glacial processes, by peatland formation, in coastal dune systems, by beavers), or they can simply be isolated depressions (such as a
kettle A kettle, sometimes called a tea kettle or teakettle, is a type of pot specialized for boiling water, commonly with a ''lid'', ''spout'', and ''handle'', or a small electric kitchen appliance of similar shape that functions in a self-contained ...
hole,
vernal pool Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland A wetland is a distinct ecosystem that ...

vernal pool
,
prairie pothole Wheatfield intersection in the Southern Saskatchewan prairies, Canada. Prairies are ecosystem An ecosystem is a community (ecology), community of living organisms in conjunction with the nonliving components of their environment, interact ...
, or simply natural undulations in undrained land) filled by runoff, groundwater, or precipitation, or all three of these. They can be further divided into four zones: vegetation zone, open water, bottom mud and surface film. The size and depth of ponds often varies greatly with the time of year; many ponds are produced by spring flooding from rivers. Ponds may be
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in ...

freshwater
or
brackish Brackish water, also sometimes termed brack water, is water occurring in a natural environment having more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) with fresh water together, as in est ...
in nature. 'Ponds' with
saltwater Saline water (more commonly known as salt water) is water Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the ...
, with a direct connection to the sea that maintains full salinity, would normally be regarded as part of the marine environment because they would not support fresh or brackish water organisms, so not really within the realm of freshwater science. Ponds are usually by definition quite shallow waterbodies with varying abundances of
aquatic plant Aquatic plants are plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; howeve ...
s and animals. Depth, seasonal water level variations, nutrients fluxes, amount of light reaching the ponds, the shape, the presence of visiting large mammals, the composition of any fish communities and salinity can all affect the types of plant and animal communities present.
Food webs A food web (or food cycle) is the natural interconnection of food chain The food chain in ecology is a chain of trophic relations. Food chain can refer to the food system, the complex economic and ecological systems that bring food to consumers ...

Food webs
are based both on free-floating
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
and upon aquatic plants. There is usually a diverse array of aquatic life, with a few examples including algae, snails, fish, beetles, water bugs, frogs, turtles, otters and muskrats. Top predators may include large fish, herons, or alligators. Since fish are a major predator upon amphibian larvae, ponds that dry up each year, thereby killing resident fish, provide important refugia for amphibian breeding. Ponds that dry up completely each year are often known as
vernal pools Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland A wetland is a distinct ecosystem that ...
. Some ponds are produced by animal activity, including alligator holes and beaver ponds, and these add important diversity to landscapes. Ponds are frequently manmade or expanded beyond their original depths and bounds by
anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows: * Human imp ...
causes. Apart from their role as highly biodiverse, fundamentally natural, freshwater ecosystems ponds have had, and still have, many uses, including providing , livestock and communities, aiding in habitat restoration, serving as breeding grounds for local and migrating species, decorative components of
landscape architecture Landscape architecture is the design of outdoor areas, landmarks, and structures to achieve environmental, social-behavioural, or aesthetic outcomes. It involves the systematic design and general engineering of various structures for constructio ...
,
flood control Flood control methods are used to reduce or prevent the detrimental effects of flood A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the ...
basins, general urbanization, interception basins for pollutants and sources and sinks of greenhouse gases.


Classification

The technical distinction between a pond and a lake has not been universally standardized. Limnologists and freshwater biologists have proposed formal definitions for ''pond'', in part to include 'bodies of water where light penetrates to the bottom of the waterbody,' 'bodies of water shallow enough for rooted water plants to grow throughout,' and 'bodies of water which lack wave action on the shoreline.' Each of these definitions are difficult to measure or verify in practice and are of limited practical use, and are mostly not now used. Accordingly, some organizations and researchers have settled on technical definitions of ''pond'' and ''lake'' that rely on size alone. Some regions of the United States define a pond as a body of water with a surface area of less than 10 acres (4.0 ha).
Minnesota Minnesota () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper ...

Minnesota
, known as the "land of 10,000 lakes", is commonly said to distinguish lakes from ponds, bogs and other water features by this definition, but also says that a lake is distinguished primarily by wave action reaching the shore. Even among organizations and researchers who distinguish lakes from ponds by size alone, there is no universally recognized standard for the maximum size of a pond. The international sets the upper limit for pond size as 8
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area Area is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms o ...

hectare
s (80,000 m2; 20
acre The acre is a unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation ...

acre
s). Researchers for the British charity Pond Conservation (now called Freshwater Habitats Trust) have defined a ''pond'' to be 'a man-made or natural waterbody that is between 1 m2(0.00010 hectares; 0.00025 acres) and 20,000 m2 (2.0 hectares; 4.9 acres) in area, which holds water for four months of the year or more.' Other European biologists have set the upper size limit at 5 hectares (50,000 m2; 12 acres). In North America, even larger bodies of water have been called ponds; for example, Crystal Lake at 33 acres (130,000 m2; 13 ha),
Walden Pond Walden Pond is a pond in Concord, Massachusetts Concord () is a town in Middlesex County, Massachusetts Middlesex County is located in the Commonwealth of Massachusetts Massachusetts (, ), officially the Commonwealth of Massachusetts, ...

Walden Pond
in
Concord, Massachusetts Concord () is a town in Middlesex County, Massachusetts Middlesex County is located in the Commonwealth of Massachusetts Massachusetts (, ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New E ...
at 61 acres (250,000 m2; 25 ha), and nearby
Spot Pond Spot Pond is a lake in Middlesex County, Massachusetts, Middlesex County, in the U.S. state of Massachusetts. The pond is within the Middlesex Fells Reservation, a Massachusetts state park. It is almost entirely located within the boundaries of St ...
at 340 acres (140 ha). There are numerous examples in other states, where bodies of water less than 10 acres (40,000 m2; 4.0 ha) are being called lakes. As the case of Crystal Lake shows,
marketing Marketing is the process of intentionally stimulating demand for and purchases of goods and services; potentially including selection of a target audience; selection of certain attributes or themes to emphasize in advertising; operation of adv ...

marketing
purposes can sometimes be the driving factor behind the categorization. In practice, a body of water is called a pond or a lake on an individual basis, as conventions change from place to place and over time. In origin, a pond is a variant form of the word pound, meaning a confining enclosure. In earlier times, ponds were artificial and utilitarian, as
stew pondA stew pond or stew is a fish pond used to store live fish ready for eating.Nash, Colin (2011''The History of Aquaculture''p. 28–29, John Wiley and Sons. . During the Middle Ages, stews were often attached to monasteries, to supply fish over the w ...
s, mill ponds and so on. The significance of this feature seems, in some cases, to have been lost when the word was carried abroad with emigrants. However, some parts of New England contain "ponds" that are actually the size of a small lake when compared to other countries. In the United States, natural pools are often called ponds. Ponds for a specific purpose keep the adjective, such as "stock pond", used for watering livestock. The term is also used for temporary accumulation of water from
surface runoff Surface runoff (also known as overland flow) is the flow of water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it ac ...
(''ponded'' water). There are various regional names for naturally occurring ponds. In Scotland, one of the terms is
loch Loch () is the Scottish Gaelic Scottish Gaelic ( gd, Gàidhlig ), also known as Scots Gaelic and Gaelic, is a Goidelic language The Goidelic or Gaelic languages ( ga, teangacha Gaelacha; gd, cànanan Goidhealach; gv, çhengaghyn Gae ...

loch
an, which may also apply to a large body of water such as a lake. In the South Western parts of North American, lakes or ponds that are temporary and often dried up for most parts of the year are called .  These playas are simply shallow depressions in dry areas that may only fill with water on certain occasion like excess local drainage, groundwater seeping, or rain.


Formation

Any
depression Depression may refer to: Mental health * Depression (mood), a state of low mood and aversion to activity * Mood disorders characterized by depression are commonly referred to as simply ''depression'', including: ** Dysthymia ** Major depressive ...
in the ground which collects and retains a sufficient amount of water can be considered a pond, and such, can be formed by a variety of
geological Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and the processes by which th ...

geological
,
ecological Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms In biology ...
, and human terraforming events. Natural ponds are those caused by environmental occurrences. These can vary from glacial, volcanic, fluvial, or even tectonic events. Since the Pleistocene epoch, glacial processes have created most of the Northern hemispheric ponds; an example is the
Prairie Pothole Region Image:Barringer-Arial.jpg, Barringer Slough in Geology of Iowa, Iowa, a remnant of the extensive prairie wetlands that once covered the region. The Prairie Pothole Region (PPR) is an expansive area of the northern Great Plains that contains thousan ...

Prairie Pothole Region
of North America. When glaciers retreat, they may leave behind uneven ground due to bedrock
elastic rebound __NOTOC__ 350px, In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed ...
and sediment outwash plains. These areas may develop depressions that can fill up with excess precipitation or seeping ground water, forming a small pond. Kettle lakes and ponds are formed when ice breaks off from a larger glacier, is eventually buried by the surrounding glacial till, and over time melts.
Orogenies An orogeny is an event that leads to both structural Deformation (physics), deformation and compositional differentiation of the Earth's lithosphere (Crust (geology), crust and uppermost Mantle (geology), mantle) at Convergent boundary, converge ...
and other tectonic uplifting events have created some of the oldest lakes and ponds on the globe. These indentions have the tendency to quickly fill with groundwater if they occur below the local water table. Other tectonic rifts or depressions can fill with precipitation, local mountain runoff, or be fed by mountain streams. Volcanic activity can also lead to lake and pond formation through collapsed lava tubes or volcanic cones. Natural
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows int ...
s along rivers, as well as landscapes that contain many depressions, may experience spring/rainy season
flooding A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide Tides are the rise and fall of s caused by the combined effects of the fo ...

flooding
and snow melt. Temporary or vernal ponds are created this way and are important for breeding fish, insects, and amphibians, particularly in large river systems like the
Amazon Amazon usually refers to: * Amazons In Greek mythology, the Amazons (Ancient Greek: Ἀμαζόνες ''Amazónes'', singular Ἀμαζών ''Amazōn'') are portrayed in a number of ancient Greek, ancient epic poems and legends, such as the ...

Amazon
. Some ponds are solely created by animals species such as
beaver Beavers are large, semiaquatic In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interaction ...

beaver
s,
bison Bison are large, even-toed ungulate The even-toed ungulates (Artiodactyla , ) are ungulate Ungulates ( ) are members of the diverse clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural gro ...

bison
,
alligator An alligator is a crocodilia Crocodilia (or Crocodylia, both ) is an Order (biology), order of mostly large, predatory, List of semiaquatic tetrapods, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago ...

alligator
s and other crocodilians through damning and nest excavation respectively. In landscapes with organic soils, local fires can create depressions during periods of drought. These have the tendency to fill up with small amounts of precipitation until normal water levels return, turning these isolated ponds into open water. Manmade ponds are those created by human intervention for the sake of the local environment, industrial settings, or for recreational/ornamental use.


Uses

Many ecosystems are linked by water and ponds have been found to hold a greater biodiversity of species than larger freshwater lakes or river systems. As such, ponds are habitats for many varieties of organisms including plants, amphibians, fish, reptiles, waterfowl, insects and even some mammals. Ponds are used for breeding grounds for these species but also as shelter and even drinking/feeding locations for other wildlife. Aquaculture practices lean heavily on artificial ponds in order to grow and care for many different type of fish either for human consumption, research, species conservation or recreational sport. In agriculture practices, treatment ponds can be created to reduce nutrient runoff from reaching local streams or groundwater storages. Pollutants that enter ponds can often be mitigated by natural sedimentation and other biological and chemical activities within the water. As such, waste stabilization ponds are becoming popular low-cost methods for general wastewater treatment. They may also provide
irrigation Irrigation is the agricultural Agriculture is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in seden ...

irrigation
reservoir A reservoir (; from French ''réservoir'' ) is most commonly an enlarged natural or artificial lake A lake is an area filled with water, localized in a basin, surrounded by land Land is the solid surface of Earth that is not per ...

reservoir
s for struggling farms during times of drought. As urbanization continues to spread, retention ponds are becoming more common in new housing developments. These ponds reduce the risk of flooding and erosion damage from excess storm water runoff in local communities. Experimental ponds are used to test hypotheses in the fields of environmental science, chemistry, aquatic biology, and limnology. Some ponds are the life blood of many small villages in arid countries such as those in sub-Saharan Africa where bathing, sanitation, fishing, socialization, and rituals are held. In the Indian subcontinent,
Hindu Hindus (; ) are persons who regard themselves as culturally, ethnically, or religiously adhering to aspects of Hinduism Hinduism () is an Indian religion Indian religions, sometimes also termed Dharmic religions or Indic re ...

Hindu
temple monks care for sacred ponds used for religious practices and bathing pilgrims alike. In Europe during
medieval In the history of Europe The history of Europe concerns itself with the discovery and collection, the study, organization and presentation and the interpretation of past events and affairs of the people of Europe since the beginning of ...

medieval
times, it was typical for many
monastery A monastery is a building or complex of buildings comprising the domestic quarters and workplaces of monastics, monk A monk (, from el, μοναχός, ''monachos'', "single, solitary" via Latin Latin (, or , ) is a classical l ...

monastery
and
castle A castle is a type of fortification, fortified structure built during the Middle Ages predominantly by the nobility or royalty and by Military order (monastic society), military orders. Scholars debate the scope of the word ''castle'', but u ...

castle
s (small, partly self-sufficient communities) to have
fish pond A fish pond, or fishpond, is a controlled pond A pond is an area filled with water, either natural or artificial, that is smaller than a lake A lake is an area filled with water, localized in a basin, surrounded by land, apart from an ...

fish pond
s. These are still common in Europe and in
East Asia East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...

East Asia
(notably Japan), where
koi or more specifically , are colored varieties of the Amur carp (''Cyprinus rubrofuscus ''Cyprinus rubrofuscus'', the Amur carp, is a species of cyprinid fish. It is widespread in Eastern Asia East Asia is the east East is one of the ...

koi
may be kept or raised.


Pond Biodiversity

A defining feature of a pond is the presence of
standing water Water stagnation occurs when water Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all k ...
which provides
habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers at the ...

habitat
for a biological community commonly referred to as
pond life Pond life is an umbrella term for all life forms found in ponds. Although there is considerable overlap with the species lists for small lakes and even slow flowing rivers, pond life includes some species not found elsewhere and as a biome A bio ...
. Because of this, many ponds and lakes contain large numbers of endemic species that have gone through adaptive radiation to become specialized to their preferred habitat. Familiar examples might include
water lilies ''Water Lilies'' (or ''Nymphéas'', ) is a Serial imagery, series of approximately 250 oil paintings by French Impressionism, Impressionist Claude Monet (1840–1926). The paintings depict his Fondation Monet in Giverny, flower garden at Fond ...

water lilies
and other aquatic plants,
frog A frog is any member of a diverse and largely carnivorous A carnivore , meaning "meat Meat is animal flesh that is eaten as food. Humans have hunted and killed animals for meat since prehistoric times. The advent of civilization all ...

frog
s,
turtle Turtles are an order Order, ORDER or Orders may refer to: * Orderliness Orderliness is a quality that is characterized by a person’s interest in keeping their surroundings and themselves well organized, and is associated with other qu ...

turtle
s, and fish. Often, the entire margin of the pond is fringed by
wetland A wetland is a distinct ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles ...

wetland
, and these wetlands support the aquatic
food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is Consumer-resource systems, consumer-resource system. Ecologists can broadly lump a ...

food web
, provide shelter for wildlife, and stabilize the shore of the pond. This margin is also known as the littoral zone and contains much of the photosynthetic algae and plants of this ecosystem called macrophytes. Other photosynthetic organisms such as phytoplankton (suspended algae) and periphytons (organisms including cyanobacteria, detritus, and other microbes) thrive here and stand as the primary producers of pond food webs. Some grazing animals like
geese A goose (plural geese) is a bird of any of several waterfowl Anseriformes is an order of bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves , characterised by feathers, toothless beaked ...

geese
and
muskrat The muskrat (''Ondatra zibethicus'') is a medium-sized semiaquatic In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecul ...

muskrat
s consume the wetland plants directly as a source of food. In many other cases, pond plants will decay in the water. Many invertebrates and herbivorous zooplankton then feed on the decaying plants, and these lower trophic level organisms provide food for wetland species including fish,
dragonflies A dragonfly is a flying insect belonging to the order Odonata, infraorder Anisoptera (from Ancient Greek, Greek ἄνισος ''anisos'', "unequal" and πτερόν ''pteron'', "wing", because the hindwing is broader than the forewing). Adult d ...

dragonflies
, and herons both in the littoral zone and the limnetic zone. The open water limnetic zone may allow
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
to grow as sunlight still penetrates here. These algae may support yet another food web that includes aquatic insects and other small fish species. A pond, therefore, may have combinations of three different food webs, one based on larger plants, one based upon decayed plants, and one based upon algae and their specific upper trophic level consumers and predators. Hence, ponds often have many different animal species using the wide array of food sources though biotic interaction. They, therefore, provide an important source of
biological diversity Biodiversity is the biological variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic, species In biology, a species is the basic unit of biological classification, classification and a taxonomic ...
in landscapes. Opposite to long standing ponds are
vernal pond Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe ...
s. These ponds dry up for part of the year and are so called because they are typically at their peak depth in the spring (the meaning of "vernal" comes form the Latin word for
spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a heli ...
). Naturally occurring vernal ponds do not usually have fish, a major higher tropic level consumer, as these ponds frequently dry up. The absence of fish is a very important characteristic of these ponds since it prevents long chained biotic interactions from establishing. Ponds without these competitive predation pressures provides breeding locations and safe havens for endangered or migrating species. Hence, introducing fish to a pond can have seriously detrimental consequences. In some parts of the world, such as California, the vernal ponds have rare and endangered plant species. On the coastal plain, they provide habitat for endangered frogs such as the Mississippi Gopher Frog. Often groups of ponds in a given landscape - so called 'pondscapes' - offer especially high biodiversity benefits compared to single ponds. A group of ponds provides a higher degree of habitat complexity and habitat connectivity.


Stratification

Many ponds undergo a regular yearly process in the same matter as larger lakes if they are deep enough and/or protected from the wind. Abiotic factors such as UV radiation, general temperature, wind speed, water density, and even size, all have important roles to play when it comes to the seasonal effects on lakes and ponds. Spring overturn, summer stratification, autumn turnover, and an inverse winter stratification, ponds adjust their stratification or their vertical zonation of temperature due to these influences. These environmental factors affect pond circulation and temperature gradients within the water itself producing distant layers; the
epilimnion The epilimnion or surface layer is the top-most layer in a thermally Lake stratification, stratified lake, occurring above the deeper hypolimnion. It is warmer and typically has a higher pH and higher dissolved oxygen concentration than the hypoli ...
, , and
hypolimnion The hypolimnion or under lake is the dense, bottom layer of water in a thermally-stratified lake. The word hypolimnion is derived from the Greek "limnos" meaning "lake". It is the layer that lies below the thermocline A thermocline (also known ...
. Each zone has varied traits that sustain or harm specific organisms and biotic interactions below the surface depending on the season. Winter surface ice begins to melt in the Spring. This allows the water column to begin mixing thanks to solar convection and wind velocity. As the pond mixes, an overall constant temperature is reached. As temperatures increase through the summer, thermal stratification takes place. Summer stratification allows for the epilimnion to be mixed by winds, keeping a consistent warm temperature throughout this zone. Here,
photosynthesis Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Conversion (Doctor Who audio), "Conversion" (''Doctor Who'' audio), an episode of the audio drama ' ...

photosynthesis
and
primary production In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through ch ...
flourishes. However, those species that need cooler water with higher dissolved oxygen concentrations will favor the lower metalimnion or hypolimnion. Air temperature drops as fall approaches and a deep mixing layer occurs. Autumn turnover results in
isothermal In thermodynamics, an isothermal process is a type of thermodynamic process in which the temperature ''T'' of a Thermodynamic system, system remains constant: Δ''T'' = 0. This typically occurs when a system is in contact with an outside the ...

isothermal
lakes with high levels of dissolved oxygen as the water reaches an average colder temperature. Finally, winter stratification occurs inversely to summer stratification as surface ice begins to form yet again. This ice cover remains until solar radiation and convection return in the spring. Due to this constant change in vertical zonation, seasonal stratification causes habitats to grow and shrink accordingly. Certain species are bound to these distinct layers of the water column where they can thrive and survive with the best efficiency possible. For more information regarding seasonal thermal stratification of ponds and lakes, please look at "
Lake Stratification Lake stratification is the tendency of lake A lake is an area filled with water, localized in a basin, surrounded by land Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situa ...

Lake Stratification
".


Conservation and Management

Ponds provide not only environmental values, but practical benefits to society. One increasingly crucial benefit that ponds provide is their ability to act as greenhouse gas sinks. Most natural lakes and ponds are greenhouse gas sources and aid in the
flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...

flux
of these dissolved compounds. However, manmade farm ponds are becoming significant sinks for gas
mitigation Mitigation is the reduction of something harmful or the reduction of its harmful effects. It may refer to measures taken to reduce the harmful effects of hazards that remain ''in potentia'', or to manage harmful incidents that have already occurred ...
and the fight against
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
. These agriculture runoff ponds receive high level water from surrounding soils. Highly acidic drainage ponds act as catalysis for excess
CO2 Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

CO2
(Carbon Dioxide) to be converted into forms of carbon that can easily be stored in sediments. When these new drainage ponds are constructed, concentrations of bacteria that normally break down dead organic matter, such as algae, are low. As a result, breakdown and release of Nitrogen gasses from these organic materials such as N2O does not occur and thus, not added to our atmosphere. This process is also used with regular
denitrification Denitrification is a microbially facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic tab ...
in
anoxic The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of disso ...
layer of ponds. However, not all ponds have the ability to become
sinks A sink – also known by other names including sinker, washbowl, hand basin, wash basin, and simply basin – is a bowl-shaped plumbing fixture used for washing hands, dishwashing, and other purposes. Sinks have Tap (valve), taps (faucets) that ...
for
greenhouse gas A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhou ...
ses. Most ponds experience
eutrophication Eutrophication (from Greek ''eutrophos'', "well-nourished") is the process by which an entire body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokm ...

eutrophication
where faced with excessive nutrient input from fertilizers and runoff. This over-nitrifies the pond water and results in mass algae blooms and local
fish kill The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (2005) ''Plant Management in Flo ...
s. Some farm ponds are not used for runoff control but rather for livestock like
cattle Cattle, taurine cattle, Eurasian cattle, or European cattle (''Bos taurus'' or ''Bos primigenius taurus'') are large domestication, domesticated Cloven hoof, cloven-hooved herbivores. They are a prominent modern member of the subfamily Bovinae ...

cattle
or buffalo as watering and bathing holes. As mentioned in the use section, ponds are important hotspots for biodiversity. Sometimes this becomes an issue with invasive or introduced species that disrupt pond ecosystem dynamics such as
food-web A food web (or food cycle) is the natural interconnection of food chain The food chain in ecology is a chain of trophic relations. Food chain can refer to the food system, the complex economic and ecological systems that bring food to consumers ...

food-web
structure,
niche Niche may refer to: Science *Developmental niche{{third-party, date=October 2020 The developmental niche is a theoretical framework for understanding and analyzing how culture Culture () is an umbrella term which encompasses the social behav ...
partitioning, and guild assignments. This varies from introduced fish species such as the
Common Carp The common carp or European carp (''Cyprinus carpio'') is a widespread freshwater fish Fish are , , -bearing animals that lack with . Included in this definition are the living , s, and and as well as various extinct related groups. Ar ...

Common Carp
that eat native water plants or Northern Snakeheads that attack breeding amphibians, aquatic snails that carry infectious parasites that kill other species, and even rapid spreading aquatic plants like
Hydrilla ''Hydrilla'' (waterthyme) is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may al ...

Hydrilla
and
Duckweed Lemnoideae is a subfamily of flowering aquatic plant Aquatic plants are plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things th ...

Duckweed
that can restrict water flow and cause overbank flooding. Ponds, depending on their orientation and size, can spread their wetland habitats into the local riparian zones or watershed boundaries. Gentle slopes of land into ponds provides an expanse of habitat for wetland plants and wet meadows to expand beyond the limitation of the pond. However, the construction of retaining walls, lawns, and other urbanized developments can severely degrade the range of pond habitats and the longevity of the pond itself. Roads and highways act in the same manor, but they also interfere with amphibians and turtles that migrate to and from ponds as part of their annual breeding cycle and should be kept as far away from established ponds as possible. Because of these factors, gently sloping shorelines with broad expanses of wetland plants not only provide the best conditions for wildlife, but they help protect water quality from sources in the surrounding landscapes. It is also beneficial to allow water levels to fall each year during drier periods in order to re-establish these gentile shorelines. In landscapes where ponds are artificially constructed, they are done so to provide wildlife viewing and conservation opportunities, to treat wastewater, for sequestration and pollution containment, or for simply aesthetic purposes. For natural pond conservation and development, one way to stimulate this is with general stream and river restoration. Many small rivers and streams feed into or from local ponds within the same watershed. When these rivers and streams flood and begin to meander, large numbers of natural ponds, including
vernal pool Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland A wetland is a distinct ecosystem that ...

vernal pool
s and
wetland A wetland is a distinct ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles ...

wetland
s, develop.


Examples

Some notable ponds are: *
Big Pond, Nova Scotia Big Pond ''(Scottish Gaelic: Am Pòn Mòr)'' (2001 pop.: 47) is a community in the Cape Breton Regional Municipality Cape Breton Regional Municipality (often referred to as simply "CBRM") is the Canada, Canadian province of Nova Scotia's second ...

Big Pond, Nova Scotia
*
Walden Pond Walden Pond is a pond in Concord, Massachusetts Concord () is a town in Middlesex County, Massachusetts Middlesex County is located in the Commonwealth of Massachusetts Massachusetts (, ), officially the Commonwealth of Massachusetts, ...

Walden Pond
,
Massachusetts Massachusetts (, ), officially the Commonwealth of Massachusetts, is the most populous state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ...

Massachusetts
, United States — associated with
Henry David Thoreau Henry David Thoreau (July 12, 1817May 6, 1862) was an American naturalist, essayist, poet, and philosopher. A leading Transcendentalism, transcendentalist, he is best known for his book ''Walden'', a reflection upon simple living in natural s ...

Henry David Thoreau
* Christian Pond,
Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. The List of U.S. states and territories by area, 10th largest state by area, it is also the List of U.S. states and territories b ...
, United States * Hampstead Ponds, London * Rožmberk Pond,
Czech Republic The Czech Republic, also known by its short-form name Czechia and formerly known as Bohemia, is a landlocked country in Central Europe. It is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to ...


See also

* * *


References


Further reading

* Hughes, F.M.R. (ed.). (2003). ''The Flooded Forest: Guidance for policy makers and river managers in Europe on the restoration of floodplain forests''. FLOBAR2, Department of Geography, University of Cambridge, Cambridge, UK. 96 p. * Environment Canada. (2004). ''How Much Habitat is Enough? A Framework for Guiding Habitat Rehabilitation in Great Lakes Areas of Concern''. 2nd ed. 81 p. * Herda DJ (2008) ''Zen & the Art of Pond Building'' Sterling Publishing Company. . * W.H. MacKenzie and J.R. Moran (2004). ''Wetlands of British Columbia: A Guide to Identification''. Ministry of Forests, Land Management Handbook 52. {{Authority control Lacustrine landforms Habitats
Bodies of water {{See also, Limnology Compare to :Landforms and :Wetlands Bodies of water may exist within land areas or within other bodies of water and may be natural, man-made or a combination. Water Physical geography Hydrography Natural resources, +Water A ...