A lake ecosystem includes biotics (live) plants, animals and micro-organisms, as well as abiotic (non-living) physical and chemical interactions.
Lake ecosystems are a prime example of a lizard ecosystem . Lentic refers to silent or relatively silent water, from Latin lentus , which means slow. Flammable waters range from ponds to lakes to wetlands, and many of these articles apply to general lime ecosystems. The lethal ecosystem can be compared to the lotus ecosystem, which involves the flow of terrestrial waters such as rivers and rivers. Together, these two areas form a more common area of ​​study than freshwater or aquatic ecology.
The tapering system is diverse, ranging from a temporary small rainwater pool, a few inches into Lake Baikal, which has a maximum depth of 1740 m. The general difference between ponds/ponds and lakes is unclear, but Brown claims that ponds and ponds have all the underlying surfaces exposed to light, whereas lakes do not. In addition, some lakes become seasonal stratification (discussed in more detail below.) Pools and ponds have two areas: the pelagic open water zone, and the benthic zone, which comprises the lower regions and beaches. Since the lake has a lower part that is not exposed to light, the system has additional zones, which are profundal. These three areas can have very different abiotic conditions and, therefore, host species that are specifically adapted to live there.
Video Lake ecosystem
Faktor abiotik penting
Light
Light provides the solar energy necessary to drive the process of photosynthesis, the main energy source of the lentik system. The amount of light received depends on the combination of several factors. Small ponds may experience shade by surrounding trees, while cloud cover can affect the availability of light in all systems, regardless of size. Seasonal and diurnal considerations also play a role in the availability of light due to the shallower angle of light attacking the water, the more light is lost by reflection. This is known as Beer's law. Once the light has penetrated the surface, it may also be spread by suspended particles in the water column. This scattering reduces the total amount of light as it increases in depth. The lake is divided into areas of photography and aphotic, sunlight that receives before and the latter is below the depth of light penetration, thus lacking the capacity of photosynthesis. In relation to lake zonation, pelagic and benthic zones are considered to be within the area of ​​photography, while the profundal zone is in the pharmacy area.
Temperature
Temperature is an important abiotic factor in the lentic ecosystem because most biota are poikilothermic, where the internal body temperature is determined by the surrounding system. Water can be heated or cooled by radiation on the surface and conduction to or from the air and surrounding substrate. Shallow pools often have a continuous temperature gradient from warm waters on the surface to the cold waters at the bottom. In addition, temperature fluctuations can be very good in this system, both dioral and seasonal.
Temperature regimes are very different in large lakes (Figure 2). In temperate climates, for example, when air temperatures rise, an ice sheet forms on the surface of a ruptured lake leaving water at about 4 ° C. This is the temperature at which water has the highest density. As the season progresses, warmer air temperatures heat up the water surface, making it less dense. Deeper water remains cool and dense as light penetration decreases. As the summer begins, two different layers become established, with a large temperature difference between them so that they remain storied. The lowest zone in the lake is the coldest and is called the hypolimnion. The upper warm zone is called epilimnion. Among these zones is a rapid temperature change wave called thermocline. During the colder autumn, heat dissipates on the surface and the epilimnion cools. When the temperature of the two zones is close enough, the water begins to mix again to create a uniform temperature, an event called the rotation of the lake. In winter, inverted stratification occurs when water near the surface cools, while water is warmer, but more solid water remains near the bottom. The thermocline is formed, and the cycle is repeated.
Wind
In exposed systems, the wind can create turbulent and spiral surface currents called the Langmuir circulation (Figure 3). Exactly how these currents become established is still not well understood, but it is clear that this involves some interaction between horizontal surface current and surface gravity waves. The visible result of this rotation, which can be seen in every lake, is the surface of the foam line parallel to the wind direction. Very light particles and small organisms are concentrated in the foam line on the surface and floating objects are negatively found in upwelling currents between two rotations. Neutral buoyancy objects tend to be evenly distributed in the water column. This volatility circulates the nutrients in the water column, making it important for many pelagic species, but its effect on benthic and profundal organisms is minimal to none, respectively. The level of nutrient circulation is a specific system, because it depends on factors such as the strength and duration of the wind, as well as the depth and productivity of the lake or pond.
Chemistry
Oxygen is essential for organismal respiration. The amount of oxygen present in the standing water depends on: 1) the transparent water area exposed to air, 2) the water circulation within the system and 3) the amount of oxygen produced and used by the existing organism. In shallow, plant-rich ponds there may be large fluctuations in oxygen, with very high concentrations occurring during the day due to photosynthesis and very low values ​​at night when respiration is the dominant process of primary producers. Thermal stratification in larger systems can also affect the amount of oxygen present in different zones. Epilimnion is oxygen-rich because it circulates rapidly, obtaining oxygen through contact with air. Hipolimnion, however, circulates very slowly and has no atmospheric contact. In addition, fewer green plants exist in hypolimnion, so there is less oxygen released from photosynthesis. In spring and autumn when mixed epilimnion and hypolimnion, oxygen becomes more evenly distributed in the system. Low oxygen levels are characteristic of the profundal zone due to the accumulation of decaying vegetation and "rain" animal matter down from pelagic and benthic zones and inability to support major producers.
Phosphorus is important for all organisms because it is a component of DNA and RNA and is involved in cell metabolism as a component of ATP and ADP. Also, phosphorus is not found in large quantities in freshwater systems, limiting photosynthesis in primary producers, making it the main determinant of production of lentik systems. The phosphorus cycle is complex, but the model described below illustrates the basic path. Phosphorus mainly enters ponds or lakes via runoff from the watershed or by atmospheric deposition. Upon entering the system, the reactive form of phosphorus is usually taken by algae and macrophytes, which release non-reactive phosphorus compounds as a by-product of photosynthesis. This phosphor can drift down and become part of benthic or profundal sediments, or it can be remineralized to a reactive form by microbes in the water column. Similarly, non-reactive phosphorus in the sediment can be remineralized into a reactive form. Sediments are generally richer phosphorus than lake water, however, suggesting that these nutrients may have a long residency time there before remineralization and are reintroduced into the system.
Maps Lake ecosystem
lantern system biota
Bacteria
Bacteria are present in all areas of tap water. Free living forms are associated with the decomposition of organic materials, biofilms on rock and plant surfaces, suspended in water columns, and in benthic and profundal zone sediments. Other forms are also associated with the guts of a lentik as a parasite or in a commensal relationship. Bacteria play an important role in the metabolic system through nutrient recycling, which is discussed in the Trophic Relation section.
Primary producer
Algae, including phytoplankton and periphyton are photosynthesis in ponds and lakes. Phytoplankton is found floating in the water column of the pelagic zone. Many species have a higher density than water that should have drowned them and ended up in benthos. To overcome this, phytoplankton have developed a mechanism of density change, by forming vacuoles and gas vesicles or by changing their shape to encourage drag, slowing their decline. The highly sophisticated adaptations used by a small number of species are flagellum-like tails that can adjust vertical position and allow movement in all directions. Phytoplankton can also maintain its presence in the water column by circulating in the Langmuir rotation. Periphyton algae, on the other hand, attach to the substrate. In lakes and ponds, they can cover all benthic surfaces. Both types of plankton are important as a food source and as a provider of oxygen.
The aquatic plants live in both the benthic and pelagic zones and can be grouped according to the mode of growth: 1) appear = rooted in the substrate but with leaves and flowers extending into the air, 2) floating-leaved = rooted in the substrate but with floating leaves, 3) drowning = growing below the surface and 4) free floating macrophytes = not rooted in the substrate and floating on the surface. These different forms of macrophytes generally occur in different areas of the benthic zone, with vegetation appearing closest to the coastline, then floating-leafed macrophytes, followed by submerged vegetation. Free floating macrophytes can occur anywhere on the surface of the system.
Water plants are more afloat than their terrestrial counterparts because fresh water has a higher density than air. This makes structural rigidity unimportant in lakes and ponds (except in stems and air leaves). Thus, the leaves and stems of most aquatic plants use less energy to build and maintain wooden tissue, investing that energy into rapid growth. To overcome the stresses caused by wind and waves, plants must be flexible and tough. Light, water depth and substrate type are the most important factors that control the distribution of submerged aquatic plants. Macrophytes are a source of food, oxygen, and habitat structures in the benthic zone, but can not penetrate the depth of the euphotic zone and therefore are not found there.
Invertebrates
Zooplankton is a small animal that hangs in the water column. Like phytoplankton, these species have developed mechanisms that prevent them from sinking into deeper waters, including body forms that trigger obstacles and complementary complementary strands such as antennas or thorns. What remains in the water column may have an advantage in terms of feeding, but the lack of this refugee zone makes zooplankton susceptible to predation. In response, some species, especially Daphnia sp., Perform daily vertical migration in the water column by passively passing to the darker lower depths of the day and actively moving toward the surface at night. Also, since conditions in the lentic system can vary greatly throughout the season, zooplankton have the ability to switch from laying regular eggs to break eggs when there is a food shortage, temperatures falling below 2 Ã, Â ° C, or if the abundance of predators is high.. This resting egg has a diapause, or period of dormancy that allows the zooplankton to deal with more favorable conditions to survive when they finally hatch. The invertebrates that inhabit benthic zones are numerically dominated by small species and rich species compared to zooplankton from open water. They include crustaceans (eg crabs, crayfish, and shrimp), mollusks (eg shells and snails), and various types of insects. These organisms are mostly found in macrophage growth areas, where the richest resources, high oxygenated water, and the hottest part of the ecosystem are found. Strong structural macrophy beds are an important site for the accumulation of organic materials, and provide an ideal area for colonization. Sediments and plants also offer a great deal of protection from predatory fish.
Very few invertebrates can inhabit the cold, dark, and bad profundal zones. They are often red because of the large amount of hemoglobin, which greatly increases the amount of oxygen carried to the cell. Since the concentration of oxygen in this zone is low, most species build tunnels or borrows where they can hide and make the minimum required movement to circulate water, drawing oxygen to them without spending much energy.
Fish and other vertebrates
Fish have various physiological tolerances depending on which species they are from. They have different lethal temperatures, dissolved oxygen requirements, and spawning needs based on their activity and behavior levels. Because fish are so mobile, they are able to handle abiotic factors that do not fit in one zone by simply migrating to another. A detrital feeder in the profundal zone, for example, that finds the oxygen concentration down too low can feed closer to the benthic zone. A fish can also change its shelter during different parts of its life history: hatch in the sedimentary nest, then move to the skinny benthic zone to thrive in a food-protected environment, and eventually into the pelagic zone as an adult.
Other vertebrate taxis inhabit the system as well. These include amphibians (eg salamanders and frogs), reptiles (eg snakes, turtles, and crocodiles), and large numbers of waterfowl species. Most of these vertebrates spend part of their time in terrestrial habitats and thus are not directly affected by abiotic factors in lakes or ponds. Many fish species are important as consumers and species of prey for larger vertebrates mentioned above.
Trophic connection
Primary producer
The tapering system gets most of their energy from photosynthesis done by aquatic plants and algae. This autochthonous process involves a combination of carbon dioxide, water, and solar energy to produce soluble carbohydrates and oxygen. In a lake or pond, the level of photosynthesis potential generally decreases with depth due to the light attenuation. Photosynthesis, however, is often low in a few millimeters over the surface, possibly due to inhibition by ultraviolet light. The exact depth and photosynthesis measurements of this curve are specific and depend on: 1) total photosynthetic cell biomass, 2) the amount of light attenuation and 3) the abundance and frequency range of light absorbing pigments (ie, chlorophyll) in photosynthetic cells. The energy created by these major producers is important for society as it is transferred to higher trophic levels through consumption.
Bacteria
Most of the bacteria in lakes and ponds acquire their energy by decomposing vegetation and animal matter. In the pelagic zone, dead fish and sometimes allochthonous input from litterfall are examples of rough particulate organic matter (CPOM & gt; 1 mm). The bacteria degrade this into fine particulate organic matter (FPOM & lt; 1 mm) and then further into the usable nutrients. Small organisms such as plankton are also characterized as FPOM. Very low nutrient concentrations are released during decomposition because bacteria utilize them to build their own biomass. Bacteria, however, are consumed by protozoa, which in turn are consumed by zooplankton, and then rise to trophic levels. Nutrients, including those containing carbon and phosphorus, are put back into the water column at a number of points along this food chain through excretion or death of the organism, making it available again for bacteria. This regeneration cycle is known as microbial loop and is a key component of the food web lentik.
Decomposition of organic matter can continue in the benthic and profundal zone if the material falls through the water column before it is completely digested by pelagic bacteria. Bacteria are found in the largest abundance here in the sediments, where they are usually 2-1000 times more common than in the water column.
Benthic Invertebrates
Benthic invertebrates, due to their high species richness, have many methods of catching prey. The filter feeder creates the current through a siphon or beats the cilia, to draw water and nutritional content, toward themselves to strive. Robbers use the erosion, hoarseness, and chopping adaptations to eat peripheral algae and macrophages. Members of the collector's guild trace the sediment, selecting certain particles with a raptorial appendage. Invertebrate feed deposits carelessly consume sediment, digesting all the organic matter it contains. Finally, some invertebrates belong to the predatory guild, capturing and eating live animals. The profundal zone is home to a group of unique filter feeders that use small body movements to draw currents through the holes they have made in the sediments. This feeding method requires the least amount of movement, enabling this species to conserve energy. A small number of invertebrate taxa are predators in the profundal zone. This species is likely to originate from other regions and only to the depths to feed. Most of the invertebrates in this zone are deposit feeders, getting their energy from the surrounding sediments.
Fish
Fish size, mobility, and sensory ability allow them to exploit large prey, covering several zoning areas. Like invertebrates, fish eating habits can be categorized into guilds. In the pelagic zone, herbivores graze on periphyton and macrophytes or take phytoplankton from the water column. Carnivores include fish that feed on zooplankton in water columns (zooplanktivores), insects on the surface of the water, in benthic structures, or in sediments (insectivores), and those who eat other fish (piscivores). Fish that consume detritus and gain energy by processing organic matter are called detritivores. Omnivores engulf a variety of prey, including flowers, fauna, and detrital materials. Finally, members of the parasite union obtain nutrients from host species, usually other fish or large vertebrates. Taxa fish are flexible in their eating roles, varying their diet with environmental conditions and availability of prey. Many species also experience dietary changes as they develop. Therefore, it is possible that a single fish occupies several guilds in its lifetime.
Lentic food webs
As noted in the previous section, tapering biota are connected in a complex network of trophic relationships. These organisms can be considered loosely associated with certain trophic groups (eg primary producers, herbivores, primary carnivores, secondary carnivores, etc.). Scientists have developed several theories to understand the mechanisms that control abundance and diversity in these groups. Very commonly, the top-down process dictates that the abundance of the prey taxa is dependent on the consumer action of the higher trophic level. Typically, this process operates only between two trophic levels, with no effect on the others. But in some cases, the aquatic system has a trophic cascade; for example, this may happen if the major producers experience less grazing by herbivores because these herbivores are suppressed by carnivores. The bottom-up process works when the higher number of members of the trophic level is higher depending on the availability or quality of the resource from the lower level. Finally, the theory of combined arrangement, bottom-up: top-down, combining predictions of consumer influence and resource availability. It predicts that trophic levels approaching the lowest trophic level will be most affected by bottom-up forces, while top-down effects must be strongest at the top level.
Community pattern and diversity
Wealth of local species
The biodiversity of the lentik system increases with the surface area of ​​the lake or pond. This is due to the higher probability of terrestrial species in part finding larger systems. Also, since larger systems typically have larger populations, the likelihood of extinction decreases. Additional factors, including temperature regime, pH, nutrient availability, habitat complexity, speciation level, competition, and predation have been linked to the number of species present in the system.
Succession pattern in the plankton community - PEG model
Phytoplankton and zooplankton communities in the lake system experience seasonal successes in relation to nutrient availability, predation, and competition. Sommer et al. describes these patterns as part of the Plankton Ecology Group (PEG) model, with 24 statements compiled from analysis of various systems. The following is part of this statement, as described by BrÃÆ'¶nmark and Hansson describing succession through a single seasonal cycle:
Winter Site 1. Increased availability of nutrients and light results in rapid phytoplankton growth towards the end of winter. Dominant species, such as diatoms, are small and have fast growth capabilities. 2. This plankton is consumed by zooplankton, which becomes the dominant plankton taxa.
Spring Site 3. There is a clear phase of water, because the phytoplankton population becomes depleted due to increased predation by the increase in the number of zooplankton.
Summer Site 4. Decreased Zooplankton abundance as a result of decreased phytoplankton prey and increased predation by adolescent fish.
5. With increased availability of nutrients and decreased predation of zooplankton, a diverse community of phytoplankton develops.
6. As the summer progresses, nutrients become exhausted in a predictable sequence: phosphorus, silica, and then nitrogen. The abundance of various species of phytoplankton varies in relation to their biological needs for this nutrient 7. Small zooplankton become the dominant type of zooplankton because they are less susceptible to fish predation.
Fall Site 8. Predation by fish is reduced due to lower temperatures and zooplankton of all sizes increases in number.
Winter Site 9. Cold temperatures and decreased light availability result in lower primary production rates and a decreased phytoplankton population. 10. Reproduction in zooplankton declines due to lower temperatures and fewer prey.
The PEG model presents an idealized version of this pattern of succession, while the natural system is known for its variations.
Latitude pattern
There is a well-documented global pattern that links the decline of plant and animal diversity with increasing latitude, meaning that there are fewer species as one moves toward the poles. The cause of this pattern is one of the greatest puzzles for ecologists today. Theories for explanation include energy availability, climate variability, disruption, competition, etc. Despite this global diversity gradient, this pattern can be weak for freshwater systems compared to global marine and terrestrial systems. It may be related to size, as Hillebrand and Azovsky find that smaller organisms (protozoa and plankton) do not follow strongly expected trends, while larger species (vertebrates) do so. They attribute this to better dispersion capabilities by smaller organisms, which can produce high distributions globally.
Natural lake life cycle
Lake Creation
The lake can be formed in various ways, but the most common is discussed briefly below. The oldest and largest systems are the result of tectonic activity. Lake cracks in Africa, for example, are the result of seismic activity along the separation sites of two tectonic plates. Ice-formed lakes form when glaciers recede, leaving abnormalities in the form of landscapes that are then filled with water. Finally, the oxbow lakes come from the fluvial, which is produced when a winding river curve is wedged from the main canal.
Natural Extinction
All lakes and ponds receive sediment input. Since these systems are not really developed, it is logical to assume that they will become deeper shallow, eventually becoming wetlands or terrestrial vegetation. The length of this process should depend on the combination of depth and sedimentation rate. Moss provides an example of Lake Tanganyika, which reaches a depth of 1500 m and has a sedimentation rate of 0.5 mm/year. Assuming that sedimentation is not influenced by anthropogenic factors, this system must become extinct within about 3 million years. The shallow tapering system can also fill as swamps go inside from the edges. This process operates on a much shorter time scale, taking hundreds of thousands of years to complete the extinction process.
Human impact
Acidification
Sulfur dioxide and nitrous oxide are naturally released from volcanoes, organic compounds in soils, wetlands and marine systems, but most of these compounds come from burning coal, oil, gasoline, and sulfur-containing ores. These substances dissolve in atmospheric moisture and enter the lentic system as acid rain. Lakes and ponds containing carbonate-rich rocks have natural buffers, so there is no change in pH. However, the non-rock system is very sensitive to acid input because it has a low neutralizing capacity, so the pH decreases even with only a small amount of acidic input. At pH 5-6, the diversity of algae and biomass species is greatly reduced, leading to an increase in water transparency - a hallmark of acidified lakes. As pH continues to decline, all fauna become less diverse. The most significant feature is the fish reproduction disorder. Thus, the population ends up consisting of several, old individuals who eventually die and leave the system without fish. Acid rain is very dangerous for lakes in Scandinavia, western Scotland, western Wales, and the northeastern United States.
Eutrophication
The eutrophic system contains high phosphorus concentrations (~ 30 Âμg/L), nitrogen (~ 1500Ã,Âμg/L), or both. Phosphorus enters lentic waters from sewage treatment, disposal from raw sewage, or from agricultural land runoff. Nitrogen is largely derived from agricultural fertilizers from run-off or washing and subsequent groundwater flows. Increased nutrients required for primary producers result in a large increase in the growth of phytoplankton, called plankton blooms. This bloom reduces the transparency of water, which causes the loss of submerged plants. The resulting decrease in habitat structure has a negative impact on species' utilizing it for spawning, maturation and general survival. In addition, large numbers of short-lived phytoplankton produce large amounts of dead biomass that settles in the sediments. Bacteria require large amounts of oxygen to decompose this material, reducing the oxygen concentration of water. This is especially true in stratified lakes where thermocline prevents oxygen-rich water from the surface to mix with lower levels. Low or anoxic conditions preclude the existence of many physiologically intolerant taxa of these conditions.
Invasive Species
Invasive species have been introduced to the lentic system through both deliberate events (eg game stocking and food species) as well as unintentional events (eg in water reply). These organisms can affect indigenous populations through competition for prey or habitat, predation, habitat change, hybridization, or the introduction of dangerous diseases and parasites. With respect to native species, colonizers can cause changes in size and age structure, distribution, density, population growth, and may even propel populations to extinction. Examples of leading invaders of the tapering system include the zebra mussels and the sea lamprey on the Great Lakes.
See also
- United States Environment Protection Agency - Great Lakes Ecosystem
- United States Environmental Protection Agency - Primary Limnology (PDF file)
- Freshwater environmental quality parameters
- Limnology
- Lake aeration
- The artificial water body of Maharashtra lentis
References
Bibliography
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O'Sullivan, Patrick; Reynolds, C. S. (2005). The Lakes Handbook: Lake Recovery and Rehabilitation . Wiley. ISBN 978-0-632-04795-6.
Source of the article : Wikipedia
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