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Encyclopedia > Lentic System Ecology
Fig. 1 This mountain pool is an example of a lentic system.

Lentic system ecology is the study of the biotic and abiotic interactions within still continental waters (Brown 1987). Together with lotic system ecology, which involves flowing waters such as rivers and streams, these fields form the more general study area of freshwater or aquatic ecology. Image File history File links Size of this preview: 800 × 530 pixelsFull resolution (1183 × 784 pixel, file size: 206 KB, MIME type: image/jpeg) This mountain pool is an example of a lentic system. ... Image File history File links Size of this preview: 800 × 530 pixelsFull resolution (1183 × 784 pixel, file size: 206 KB, MIME type: image/jpeg) This mountain pool is an example of a lentic system. ... Look up biotic in Wiktionary, the free dictionary. ... This article or section does not adequately cite its references or sources. ... This brook is an example of a lotic system. ... The term aquatic refers to water and can be either a noun or an adjective. ...


Lentic systems are diverse, ranging from a small, temporary rainwater pool a few inches deep to Lake Baikal, which has a maximum depth of 1740 m (Brönmark and Hansson 2005). The general distinction between pools/ponds and lakes is vague, but Brown (1987) states that ponds and pools have their entire bottom surfaces exposed to light, while lakes do not. In addition, some lakes become seasonally stratified (discussed in more detail below.) Ponds and pools have two regions. The pelagic open water zone and the benthic zone, which is comprised of the bottom and shore regions. Since lakes have deep bottom regions not exposed to light, these systems have an additional zone, the profundal (Kalff 2002). These three areas can have very different abiotic conditions and, hence, host species that are specifically adapted to live there (Brown 1987). The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... This is a scale diagram of the layers of the pelagic zone. ... This article or section contains information that has not been verified and thus might not be reliable. ... The deep zone of a water body below the range of effective light penetration. ...

Contents

Lentic system biota

Bacteria

Bacteria are present in all regions of lentic waters. Free-living forms are associated with decomposing organic material, biofilm on the surfaces of rocks and plants, suspended in the water column, and in the sediments of the benthic and profundal zones. Other forms are also associated with the guts of lentic animals as parasites or in commensal relationships (Kalff 2002). Bacteria play an important role in system metabolism through nutrient recycling (Brönmark and Hansson 2005), which will be discussed in the Trophic Relationships section. Staphylococcus aureus biofilm on an indwelling catheter. ... Common Clownfish (Amphiprion ocellaris) in their magnificent sea anemone (Heteractis magnifica) home. ...


Primary producers

Algae, including both phytoplankton and periphyton are the principle photosynthesizers in ponds and lakes. Phytoplankton are found drifting in the water column of the pelagic zone. Many species have a higher density than water which should making them sink and end up in the benthos. To combat this, phytoplankton have developed density changing mechanisms, by forming vacuoles and gas vesicles or by changing their shapes to induce drag, slowing their descent. A very sophisticated adaptation utilized by a small number of species is a tail-like flagella that can adjust vertical position and allow movement in any direction (Brönmark and Hansson 2005). Phytoplankton can also maintain their presence in the water column by being circulated in Langmuir rotations (Kalff 2002). Periphytic algae, on the other hand, are attached to a substrate. In lakes and ponds, they can cover all benthic surfaces. Both types of plankton are important as food sources and as oxygen providers (Brönmark and Hansson 2005). Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ... Periphyton is a complex matrix of algae, cyanobacteria, heterotrophic microbes, and detritus that in most cases is attached to submerged substrata in almost all aquatic ecosystems. ... A flagellum (plural, flagella) is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about. ...


Plants, or macrophytes, in lentic systems live in both the benthic and pelagic zones and can be grouped according to their manner of growth: 1) emergent macrophytes = rooted in the substrate but with leaves and flowers extending into the air, 2) floating-leaved macrophytes = rooted in the substrate but with floating leaves, 3) submersed macrophytes = not rooted in the substrate and floating beneath the surface and 4) free-floating macrophytes = not rooted in the substrate and floating on the surface (Brown 1987). These various forms of macrophytes generally occur in different areas of the benthic zone, with emergent vegetation nearest the shoreline, then floating-leaved macrophytes, followed by submersed vegetation. Free-floating macrophytes can occur anywhere on the system’s surface (Brönmark and Hansson 2005).


Aquatic plants are more buoyant than their terrestrial counterparts because freshwater has a higher density than air. This makes structural rigidity unimportant in lakes and ponds (except in the aerial stems and leaves). Thus, the leaves and stems of most aquatic plants use less energy to construct and maintain woody tissue, investing that energy into fast growth instead (Brown 1987). In order to contend with stresses induced by wind and waves, plants must be both flexible and tough (Reynolds 2004). Light is the most important factor controlling the distribution of submerged aquatic plants. Macrophytes are sources of food, oxygen, and habitat structure in the benthic zone, but cannot penetrate the depths of the euphotic zone and hence are not found there (Brown 1987, Moss 1998).


Invertebrates

Zooplankton are tiny animals suspended in the water column. Like phytoplankton, these species have developed mechanisms that keep them from sinking to deeper waters, including drag-inducing body forms and the active flicking of appendages such as antennae or spines (Brown 1987). Remaining in the water column may have its advantages in terms of feeding, but this zone’s lack of refugia leaves zooplankton vulnerable to predation. In response, some species, especially Daphnia sp., make daily vertical migrations in the water column by passively sinking to the darker lower depths during the day and actively moving towards the surface during the night. Also, because conditions in a lentic system can be quite variable across seasons, zooplankton have the ability to switch from laying regular eggs to resting eggs when there is a lack of food, temperatures fall below 2 °C, or if predator abundance is high. These resting eggs have a diapause, or dormancy period that should allow the zooplankton to encounter conditions that are more favorable to survival when they finally hatch (Gliwicz 2004). Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Species Subgenus Daphnia Subgenus Hyalodaphnia D. galeata Subgenus Ctenodaphnia Daphnia are small, mostly planktonic, crustaceans, between 0. ... Embryonic diapause, in mammals is a condition where pre-implantation blastocysts are maintained in a state of dormancy, often due to environmental cues, until such time as the environment improves. ...


The invertebrates that inhabit the benthic zone are numerically dominated by small species and are species rich compared to the zooplankton of the open water. They include Crustaceans (e.g. crabs, crayfish, and shrimp), molluscs (e.g. clams and snails), and numerous types of insects (Brönmark and Hansson 2005). These organisms are mostly found in the areas of macrophyte growth, where the richest resources, highly oxygenated water, and warmest portion of the ecosystem are found. The structurally diverse macrophyte beds are important sites for the accumulation of organic matter, and provide an ideal area for colonization. The sediments and plants also offer a great deal of protection from predatory fishes (Kalff, 2002).


Very few invertebrates are able to inhabit the cold, dark, and oxygen poor profundal zone. Those that can are often red in color due to the presence of large amounts of hemoglobin, which greatly increases the amount of oxygen carried to cells (Brown 1987). Because the concentration of oxygen within this zone is low, most species construct tunnels or borrows in which they can hide and make the minimum movements necessary to circulate water through, drawing oxygen to them without expending much energy. (Brown 1987) 3-dimensional structure of hemoglobin. ...


Fishes and other vertebrates

Fishes have a range of physiological tolerances that are dependent upon which species they belong to. They have different lethal temperatures, dissolved oxygen requirements, and spawning needs that are based on their activity levels and behaviors. Because fishes are highly mobile, they are able to deal with unsuitable abiotic factors in one zone by simply moving to another. A detrital feeder in the profundal zone, for example, that finds the oxygen concentration has dropped too low may feed closer to the benthic zone. A fish might also alter its residence during different parts of its life history: hatching in a sediment nest, then moving to the weedy benthic zone to develop in a protected environment with food resources, and finally into the pelagic zone as an adult.


Other vertebrate taxa inhabit lentic systems as well. These include amphibians (e.g. salamanders and frogs), reptiles (e.g. snakes, turtles, and alligators), and a large number of waterfowl species (Moss 1998). Most of these vertebrates spend part of their time in terrestrial habitats and thus are not directly affected by abiotic factors in the lake or pond. Many fish species are important as consumers and as prey species to the larger vertebrates mentioned above.


Trophic relationships

Primary producers

Lentic systems gain most of their energy from photosynthesis performed by aquatic plants and algae. This autochthonous process involves the combination of carbon dioxide, water, and solar energy to produce carbohydrates and dissolved oxygen. Within a lake or pond, the potential rate of photosynthesis generally decreases with depth due to light attenuation. Photosynthesis, however, is often low at the top few millimeters of the surface, likely due to inhibition by ultraviolet light. The exact depth and photosynthetic rate measurements of this curve are system specific and depend upon: 1) the total biomass of photosynthesizing cells, 2) the amount of light attenuating materials and 3) the abundance and frequency range of light absorbing pigments (i.e. chlorophylls) inside of photosynthesizing cells (Moss 1998). The energy created by these primary producers is important for the community because it is transferred to higher trophic levels via consumption. Chlorophyll (ancient Greek: chloros = green and phyllon = leaf) is a green photosynthetic pigment found in plants, algae, and cyanobacteria. ...


Bacteria

The vast majority of bacteria in lakes and ponds obtain their energy by decomposing vegetation and animal matter. In the pelagic zone, dead fishes and the occasional allochtohnous input of litterfall are examples of coarse particulate organic matter (CPOM>1 mm). Bacteria degrade these into fine particulate organic matter (FPOM<1 mm) and then further into usable nutrients. Small organisms such as plankton are also characterized as FPOM. Very low concentrations of nutrients are released during decomposition because the bacteria are utilizing them to build their own biomass. Bacteria, however, are consumed by protozoa, which are in turn consumed by zooplankton, and then further up the trophic levels. Nutrients, including those that contain carbon and phosphorus, are reintroduced into the water column at any number of points along this food chain via excretion or organism death, making them available again for bacteria. This regeneration cycle is known as the microbial loop and is a key component of lentic food webs (Brönmark and Hansson 2005). Wikisource has an original article from the 1911 Encyclopædia Britannica about: Protozoa Protozoa (in Greek proto = first and zoa = animals) are single-celled eukaryotes (organisms whose cells have nuclei) that commonly show characteristics usually associated with animals, most notably mobility and heterotrophy. ... The microbial loop is a term coined to describe a trophic pathway in aquatic environments where dissolved organic carbon (DOC) is reintroduced to the food web through the incorporation into bacteria. ...


The decomposition of organic materials can continue in the benthic and profundal zones if the matter falls through the water column before being completely digested by the pelagic bacteria. Bacteria are found in the greatest abundance here in sediments, where they are typically 2-1000 times more prevalent than in the water column (Kalff 2002).


Invertebrates

Invertebrates can be divided into feeding guilds based on their method of prey capture. Zooplankton rely on a combination of dissolved organic matter and particulates for survival. Zooplankton concentrate unicellular algae, bacteria, and detritus in the pelagic zone by sieving through morphological structures or with the creation of rotary currents that can centrifuge particles into a larger mass for digestion. These processes are energetically efficient, but they do not allow for the selection of usable material. As a result, a portion of the catch is invaluable as a food source and must be discarded. When capturing larger particles, including other zooplankton taxa, each particle is procured individually with a raptorial appendage. This type of feeding is energetically more costly, but the nutritional returns can be greater because selection is involved (Gliwicz 2003).


Benthic invertebrates, due to their high level of species richness, have many methods of prey capture. Filter feeders create currents via siphons or beating cilia, to pull water and its nutritional contents, towards themselves for straining. Grazers use scraping, rasping, and shredding adaptations to feed on periphytic algae and macrophytes. Members of the collector guild browse the sediments, picking out specific particles with raptorial appendages. Deposit feeding invertebrates indiscriminately consume sediment, digesting any organic material it contains. Finally, some invertebrates belong to the predator guild, capturing and consuming living animals (Jónasson 2003, Brönmark and Hansson 2005). Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ...


The profundal zone is home to a unique group of filter feeders that use small body movements to draw a current through burrows that they have created in the sediment. This mode of feeding requires the least amount of motion, allowing these species to conserve energy (Brown 1987). A small number of invertebrate taxa are predators in the profundal zone. These species are likely from other regions and only come to these depths to feed. The vast majority of invertebrates in this zone are deposit feeders, getting their energy from the surrounding sediments (Jónasson 2003).


Fish

Fish size, mobility, and sensory capabilities allow them to exploit a broad prey base, covering multiple zonation regions. Like invertebrates, fish feeding habits can be categorized into guilds. In the pelagic zone, herbivores graze on periphyton and macrophytes or pick phytoplankton out of the water column. Carnivores include fishes that feed on zooplankton in the water column (zooplanktivores), insects at the water’s surface, on benthic structures, or in the sediment (insectivores), and those that feed on other fishes (piscivores). Fish that consume detritus and gain energy by processing its organic material are called detritivores. Omnivores ingest a wide variety of prey, encompassing floral, faunal, and detrital material. Finally, members of the parasitic guild acquire nutrition from a host species, usually another fish or large vertebrate (Brönmark and Hansson 2005). Fish taxa are flexible in their feeding roles, varying their diets with environmental conditions and prey availability. Many species also undergo a diet shift as they develop. Therefore, it is likely that any single fish occupies multiple feeding guilds within its lifetime (Winfield 2003). In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... This tigers sharp teeth and strong jaws are the classical physical traits expected from carnivorous mammalian predators A carnivore (IPA: ), meaning meat eater (Latin carne meaning flesh and vorare meaning to devour), is an animal that eats a diet consisting mainly of meat, whether it comes from live animals... Any organism with a diet that consists chiefly of insects and similar small creatures is an insectivore. ... This page is a candidate to be moved to Wiktionary. ... A dung beetle rolling a ball of dung Detritivores (also known as saprophages, detrivores or detritus feeders) are organisms that recycle detritus (decomposing organic material), returning it into the food chain. ... A parasite is an organism that lives in or on the living tissue of a host organism at the expense of it. ...


Lentic food webs

As noted in the previous sections, the lentic biota are linked in complex web of trophic relationships. These organisms can be considered to loosely be associated with specific trophic groups (eg. primary producers, herbivores, primary carnivores, secondary carnivores, etc.). Scientists have developed several theories in order to understand the mechanisms that control the abundance and diversity within these groups. Very generally, top-down processes dictate that the abundance of prey taxa is dependant upon the actions of consumers from higher trophic levels. Typically, these processes operate only between two trophic levels, with no effect on the others. In some cases, however, aquatic systems experience a trophic cascade; for example, this might occur if primary producers experience less grazing by herbivores because these herbivores are suppressed by carnivores. Bottom-up processes are functioning when the abundance or diversity of members of higher trophic levels is dependent upon the availability or quality of resources from lower levels. Finally, a combined regulating theory, bottom-up:top-down, combines the predicted influences of consumers and resource availability. It predicts that trophic levels close to the lowest trophic levels will be most influenced by bottom-up forces, while top-down effects should be strongest at top levels (Brönmark and Hansson 2005). Top-down and Bottom-up are approaches to the software development process, and by extension to other procedures, mostly involving software. ... Trophic cascades occur when predators in a food chain suppress the abundance of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate trophic level is an herbivore). ... Top-down and Bottom-up are approaches to the software development process, and by extension to other procedures, mostly involving software. ...


Community patterns and diversity

Local species richness

The biodiversity of a lentic system increases with the surface area of the lake or pond. This is attributable to the higher likelihood of partly terrestrial species of finding a larger system. Also, because larger systems typically have larger populations, the chance of extinction is decreased (Browne 1981). Additional factors, including temperature regime, pH, nutrient availability, habitat complexity, speciation rates, competition, and predation, have been linked to the number of species present within systems (Brönmark and Hansson 2005).


Succession patterns in plankton communities – The PEG model

Phytoplankton and zooplankton communities in lake systems undergo seasonal succession in relation to nutrient availability, predation, and competition. Sommer et al. (1986) described these patterns as part of the Plankton Ecology Group (PEG) model, with 24 statements constructed from the analysis of numerous systems. The following includes a subset of these statements, as explained by Brönmark and Hansson (2005) illustrating succession through a single seasonal cycle:


Winter
1. Increased nutrient and light availability result in rapid phytoplankton growth towards the end of winter. The dominant species, such as diatoms, are small and have quick growth capabilities. 2. These plankton are consumed by zooplankton, which become the dominant plankton taxa.


Spring
3. A clear water phase occurs, as phytoplankton populations become depleted due to increased predation by growing numbers of zooplankton.


Summer
4. Zooplankton abundance declines as a result of decreased phytoplankton prey and increased predation by juvenile fishes. 5. With increased nutrient availability and decreased predation from zooplankton, a diverse phytoplankton community develops. 6. As the summer continues, nutrients become depleted in a predictable order: phosphorus, silica, and then nitrogen. The abundance of various phytoplankton species varies in relation to their biological need for these nutrients. 7. Small-sized zooplankton become the dominant type of zooplankton because they are less vulnerable to fish predation. The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...


Fall
8. Predation by fishes is reduced due to lower temperatures and zooplankton of all sizes increase in number.


Winter
9. Cold temperatures and decreased light availability result in lower rates of primary production and decreased phytoplankton populations. 10. Reproduction in zooplankton decreases due to lower temperatures and less prey.


The PEG model presents an idealized version of this succession pattern, while natural systems are known for their variation (Brönmark and Hansson 2005).


Latitudinal patterns

There is a well-documented global pattern that correlates decreasing plant and animal diversity with increasing latitude, that is to say, there are fewer species as one moves towards the poles. The cause of this pattern is one of the greatest puzzles for ecologists today. Theories for its explanation include energy availability, climatic variability, disturbance, competition, etc. (Brönmark and Hansson 2005). Despite this global diversity gradient, this pattern can be weak for freshwater systems compared to global marine and terrestrial systems (Hillebrand 2004). This may be related to size, as Hillebrand and Azovsky (2001) found that smaller organisms (protozoa and plankton) did not follow the expected trend strongly, while larger species (vertebrates) did. They attributed this to better dispersal ability by smaller organisms, which may result in high distributions globally (Brönmark and Hansson 2005).


Natural lake lifecycles

Lake creation

Lakes can be formed in a variety of ways, but the most common are discussed briefly below. The oldest and largest systems are the result of tectonic activities. The rift lakes in Africa, for example are the result of seismic activity along the site of separation of two tectonic plates. Ice-formed lakes are created when glaciers recede, leaving behind abnormalities in the landscape shape that are then filled with water. Finally, oxbow lakes are fluvial in origin, resulting when a meandering river bend is pinched off from the main channel (Brönmark and Hansson 2005). ... Austrias longest glacier, the Pasterze, winds its 8 km (5 mile) route at the foot of Austrias highest mountain, the Grossglockner A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... Songhua River, northeast China. ... The word fluvial is used in geography and earth science to refer to all topics related to flowing water. ...


Natural extinction

All lakes and ponds receive sediment inputs. Since these systems are not really expanding, it is logical to assume that they will become increasingly shallower in depth, eventually becoming wetlands or terrestrial vegetation. The length of this process should depend upon a combination of depth and sedimentation rate. Moss (1998) gives the example of Lake Tanganyika, which reaches a depth of 1500 m and has a sedimentation rate of 0.5 mm/yr. Assuming that sedimentation is not influenced by anthropogenic factors, this system should go extinct in approximately 3 million years. Shallow lentic systems might also fill in as swamps encroach inward from the edges. These processes operate on a much shorter timescale, taking hundreds to thousands of years to complete the extinction process (Moss 1989). Lake Tanganyika is a large lake in central Africa (3° 20 to 8° 48 South and from 29° 5 to 31° 15 East). ...


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Human Impacts

Acidification

Sulfur dioxide and nitrogen oxides are naturally released from volcanoes, organic compounds in the soil, wetlands, and marine systems, but the majority of these compounds come from the combustion of coal, oil, gasoline, and the smelting of ores containing sulfur (Kalff 2002). These substances dissolve in atmospheric moisture and enter lentic systems as acid rain (Brown 1987). Lakes and ponds that contain bedrock that is rich in carbonates have a natural buffer, resulting in no alteration of pH. Systems without this bedrock, however, are very sensitive to acid inputs because they have a low neutralizing capacity, resulting in pH declines even with only small inputs of acid (Kalff 2002). At a pH of 5-6 algal species diversity and biomass decrease considerably, leading to an increase in water transparency – a characteristic feature of acidified lakes. As the pH continues lower, all fauna becomes less diverse. The most significant feature is the disruption of fish reproduction. Thus, the population is eventually composed of few, old individuals that eventually die and leave the systems without fishes. (Kalff 2002, Brönmark and Hansson 2005). Acid rain has been especially harmful to lakes in the Northeastern United States. Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... Nitrogen has six different oxides: Nitric oxide (NO) Nitrous oxide (N2O) Nitrogen dioxide (NO2) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen pentoxide (N2O5) The term nitrogen oxide is imprecise and can be used to refer to any of these or to a mixture of them. ... The term acid rain also known as acid precipitation is commonly used to mean the deposition of acidic components in rain, snow, dew, or dry particles. ...


Eutrophication

Eutrophic systems contain a high concentration of phosphorus (~30+µg/L), nitrogen (~1500+µg/L), or both (Brönmark and Hansson 2005). Phosphorus enters lentic waters from wastewater treatment effluents, discharge from raw sewage, or from runoff of farmland. Nitrogen mostly comes from agricultural fertilizers from runoff or leaching and subsequent groundwater flow. This increase in nutrients required for primary producers results in a massive increase of phytoplankton growth, termed a plankton bloom. This bloom decreases water transparency, leading to the loss of submerged plants. The resultant reduction in habitat structure has negative impacts on the species’ that utilize it for spawning, maturation and general survival. Additionally, the large number of short-lived phytoplankton result in a massive amount of dead biomass settling into the sediment (Moss 1998). Bacteria need large amounts of oxygen to decompose this material, reducing the oxygen concentration of the water. This is especially pronounced in stratified lakes when the thermocline prevents oxygen rich water from the surface to mix with lower levels. Low or anoxic conditions preclude the existence of many taxa that are not physiologically tolerant of these conditions (Brönmark and Hansson 2005). Eutrophication is caused by the increase of chemical nutrients, typically compounds containing nitrogen or phosphorus, in an ecosystem. ... Sewage treatment is the process that removes the majority of the contaminants from waste-water or sewage and produces both a liquid effluent suitable for disposal to the natural environment and a sludge. ...


Invasive species

Invasive species have been introduced to lentic systems through both purposeful events (e.g. stocking game and food species) as well as unintentional events (e.g. in ballast water). These organisms can affect natives via competition for prey or habitat, predation, habitat alteration, hybridization, or the introduction of harmful diseases and parasites (Giller and Malmqvist 1998). With regard to native species, invaders may cause changes in size and age structure, distribution, density, population growth, and may even drive populations to extinction (Brönmark and Hansson 2005). Examples of prominent invaders of lentic systems include the zebra mussel and sea lamprey in the Great Lakes. Lantana invasion of abandoned citrus plantation; Moshav Sdey Hemed, Israel The term invasive species refers to a subset of introduced species or non-indigenous species that are rapidly expanding outside of their native range. ... Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. ... In genetics, hybridisation is the process of mixing different species or varieties of organisms. ... This article does not cite its references or sources. ... Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey is a type of fish with a toothed, funnel-like, jawless sucking mouth, with which most species bore into the flesh of other fishes to suck their blood. ...


References

Brönmark, C. and L.A. Hansson 2005. The Biology of Lakes and Ponds. Oxford University Press, Oxford. Pp. 285.


Brown, A.L. 1987. Freshwater Ecology. Heinimann Educational Books, London. Pp. 163.


Browne, R.A. 1981. Lakes as islands: biogeographic distribution, turnover rates, and species composition in the lakes of central New York. Journal of Biogeography. 8:75-83.


Giller, S. and B. Malmqvist. 1998. The Biology of Streams and Rivers. Oxford University Press, Oxford. Pp. 296.


Gliwicz, Z.M. 2004. Zooplankton. In: The Lakes Handbook, P.E. O’Sullivan and C.S. Reynolds Eds. Pp. 461-516.


Hillebrand, H. 2004. On the generality of the latitudinal diversity gradient. American Naturalist. 163:192-211.


Hillebrand, H. and A.I. Azovsky. 2001. Body size determines the strength of the latitudinal diversity gradient. Ecography. 24:251-256.


Jónasson, P.M. 2003. Benthic Invertebrates. In: The Lakes Handbook, P.E. O’Sullivan and C.S. Reynolds Eds. Pp. 341-416.


Kalff, J. 2002. Limnology. Prentice Hall, Upper Saddle, NJ. Pp. 592.


Moss, B. 1998. Ecology of Freshwaters: man and medium, past to future. Blackwell Science, London. Pp. 557.


Sommer, U., Gliwicz, Z.M., Lampert, W. and A. Duncan. 1986. The PEG-model of seasonal succession of planktonic events in freshwaters. Archiv für Hydrobiologie. 106:433-471.


Winfield, I.J. 2003. Fish Population Ecology. In: The Lakes Handbook, P.E. O’Sullivan and C.S. Reynolds Eds. Pp. 517-537.


See also

  • United States Environmental Protection Agency - Great Lakes Ecosystems
  • United States Environmental Protection Agency - Limnology Primer (PDF file)

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