Misplaced Pages

#771228

99-447: The River Continuum Concept is based on the idea that a watercourse is an open ecosystem that is in constant interaction with the bank, and moving from source to mouth, constantly changing. Basis for this change in the overall system is due to the gradual change of physical environmental conditions such as the width, depth, water, flow characteristics, temperature, and the complexity of the water. According to Vannote's hypothesis, which

198-587: A channel . Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers , while smaller, less voluminous and more intermittent streams are known as streamlets , brooks or creeks . The flow of a stream is controlled by three inputs – surface runoff (from precipitation or meltwater ), daylighted subterranean water , and surfaced groundwater ( spring water ). The surface and subterranean water are highly variable between periods of rainfall. Groundwater, on

297-609: A Great Lake Drainage Basin river continuum. Verh. Internat. Verein. Limnol. 21:841-849. 14. Vannote, R.L. 1981. The river continuum: a theoretical construct for analysis of river ecosystems. In: Proceed. Nat. Symp. on Freshwat. Inflow to Estuaries. Vol. 2. FWS/OBS-81/04. pp. 289–304. 15. Vannote, R.L. and G.W. Minshall. 1982. Fluvial processes and local lithology controlling abundance, structure, and composition of mussel beds. Proc. Natl. Acad. Sci. USA 79:4103-4107. 16. Cuffney, T.F. and G.W. Minshall. 1981. Life history and bionomics of Arctopsyche grandis (Trichoptera) in

396-406: A Preston plot) follow a normal (Gaussian) distribution , partly as a result of the central limit theorem (Figure 4). This means that the abundance distribution is lognormal . According to his argument, the right-skew observed in species abundance frequency histograms (including those described by Fisher et al. (1943) ) was, in fact, a sampling artifact. Given that species toward the left side of

495-403: A bed armor layer, and other depositional features, plus well defined banks due to bank erosion, are good identifiers when assessing for perennial streams. Particle size will help identify a perennial stream. Perennial streams cut through the soil profile, which removes fine and small particles. By assessing areas for relatively coarse material left behind in the stream bed and finer sediments along

594-427: A biological mechanism for the model behavior, arguing that any distribution can be produced by a variety of mechanisms. Note : This section provides a general summary of niche apportionment theory, more information can be found under niche apportionment models . Most mechanistic approaches to species abundance distributions use niche-space, i.e. available resources, as the mechanism driving abundances. If species in

693-539: A central Idaho stream. Holarc. Ecol. 4:252-262. 17. Minshall, G.W., J.T. Brock, and T.W. LaPoint. 1982. Characterization and dynamics of benthic organic matter and invertebrate functional feeding group relationships in the Upper Salmon River, Idaho (USA). Int. Revue ges. Hydrobiol. 67:793-820. 18. Bruns, D.A., G.W. Minshall, J.T. Brock, C.E. Cushing, K.W. Cummins, and R.L. Vannote. 1982. Ordination of functional groups and organic matter parameters from

792-472: A community. Assuming the shape of the total distribution can be confidently predicted from the collected data, the normal curve can be fit via statistical software or by completing the Gaussian formula : where: It is then possible to predict how many species are in the community by calculating the total area under the curve ( N ): The number of species missing from the data set (the missing area to

891-658: A continuous aquatic habitat until they reach maturity. Crayfish and other crustaceans , snails , bivalves (clams), and aquatic worms also indicate the stream is perennial. These require a persistent aquatic environment for survival. Fish and amphibians are secondary indicators in assessment of a perennial stream because some fish and amphibians can inhabit areas without persistent water regime. When assessing for fish, all available habitat should be assessed: pools, riffles, root clumps and other obstructions. Fish will seek cover if alerted to human presence, but should be easily observed in perennial streams. Amphibians also indicate

990-470: A continuous or intermittent stream. The same non-perennial channel might change characteristics from intermittent to ephemeral over its course. Washes can fill up quickly during rains, and there may be a sudden torrent of water after a thunderstorm begins upstream, such as during monsoonal conditions. In the United States, an intermittent or seasonal stream is one that only flows for part of

1089-615: A creek, especially one that is fed by a spring or seep . It is usually small and easily forded . A brook is characterised by its shallowness. A creek ( / k r iː k / ) or crick ( / k r ɪ k / ): In hydrography, gut is a small creek; this is seen in proper names in eastern North America from the Mid-Atlantic states (for instance, The Gut in Pennsylvania, Ash Gut in Delaware, and other streams) down into

SECTION 10

#1732765716772

1188-422: A drainage network. Although each tributary has its own source, international practice is to take the source farthest from the river mouth as the source of the entire river system, from which the most extended length of the river measured as the starting point is taken as the length of the whole river system, and that furthest starting point is conventionally taken as the source of the whole river system. For example,

1287-1156: A function of physical processes. Verh. Internat. Verein. Limnol. 20:1366-1375. 5. Naiman, R.J. and J.R. Sedell. 1979. Characterization of particulate organic matter transported by some Cascade Mountain streams. J. Fish. Res. Bd. Can. 36:17-31. 6. Moeller, J.R., G.W. Minshall, K.W. Cummins, R.C. Petersen, C.E. Cushing, J.R. Sedell, R.A. Larson, and R.L. Vannote. 1979. Transport of dissolved organic carbon in streams of differing physiographic characteristics. Organic Geochemistry 1:139-150. 7. Hendrickson, Jr., J.A. 1979. Analyses of species occurrences in community, continuum, and biomonitoring studies. In: G.P. Patil and M.L. Rosenzweig (eds.) Contemporary Quantitative Ecology and Related Ecometrics. Statistical Ecology Series Vol. 12, pp. 361–397. 8. Cushing, C.E., C.D. McIntire, J.R. Sedell, K.W. Cummins, G.W. Minshall, R.C. Petersen, and R.L. Vannote. 1980. Comparative study of physical-chemical variables of streams using multivariate analyses. Arch. Hydrobiol. 89:343-352. 9. Richey, J.E., J.T. Brock, R.J. Naiman, R.C. Wissmar, and R.F. Stallard. 1980. Organic carbon: oxidation and transport in

1386-402: A given species. The geometric series rank-abundance diagram is linear with a slope of – k , and reflects a rapid decrease in species abundances by rank (Figure 4). The geometric series does not explicitly assume that species colonize an area sequentially, however, the model fits the concept of niche preemption, where species sequentially colonize a region and the first species to arrive receives

1485-626: A large number of individuals in a community sample)(Figure 1). This pattern has been long-recognized and can be broadly summarized with the statement that "most species are rare". For example, Charles Darwin noted in 1859 in The Origin of Species that "... rarity is the attribute of vast numbers of species in all classes...." Species abundance patterns can be best visualized in the form of relative abundance distribution plots. The consistency of relative species abundance patterns suggests that some common macroecological "rule" or process determines

1584-450: A larger role, because resources are not spent in one place but are being constantly transported downstream. The temporal aspect of this continuity can be seen by its daily and seasonal changes. In the course of a day there are many changes in the structure of living communities, mainly due to increased resource pressure during the day (better rate of detection) and abiotic factors such as changes of temperature and light. The midreaches are

1683-540: A larger stream. Common terms for individual river distributaries in English-speaking countries are arm and channel . There are a number of regional names for a stream. A stream's source depends on the surrounding landscape and its function within larger river networks. While perennial and intermittent streams are typically supplied by smaller upstream waters and groundwater, headwater and ephemeral streams often derive most of their water from precipitation in

1782-532: A majority of the macro invertebrate structure in this area, with the predator's share remaining unchanged. In the lower reaches, there is a large flux in particulate material and also a decrease in production through photosynthesis, due to an increase in water cloudiness (turbidity) and surface film from suspended FPOM. Here, like the headwaters, respiration outpaces photosynthesis, making the ratio again less than 1 (P: R <1). The living community in these areas are made up of almost exclusively collectors, as well as

1881-410: A particular marine environment. Relative species abundances follow very similar patterns over a wide range of ecological communities. When plotted as a histogram of the number of species represented by 1, 2, 3, ..., n individuals usually fit a hollow curve, such that most species are rare, (represented by a single individual in a community sample) and relatively few species are abundant (represented by

1980-404: A path into mines or other underground chambers. According to official U.S. definitions, the channels of intermittent streams are well-defined, as opposed to ephemeral streams, which may or may not have a defined channel, and rely mainly on storm runoff, as their aquatic bed is above the water table . An ephemeral stream does not have the biological, hydrological, and physical characteristics of

2079-412: A perennial stream and include tadpoles , frogs , salamanders , and newts . These amphibians can be found in stream channels, along stream banks, and even under rocks. Frogs and tadpoles usually inhabit shallow and slow moving waters near the sides of stream banks. Frogs will typically jump into water when alerted to human presence. Well defined river beds composed of riffles, pools, runs, gravel bars,

SECTION 20

#1732765716772

2178-483: A perennial stream, fine sediment may cling to riparian plant stems and tree trunks. Organic debris drift lines or piles may be found within the active overbank area after recent high flow. Streams, headwaters, and streams flowing only part of the year provide many benefits upstream and downstream. They defend against floods, remove contaminants, recycle nutrients that are potentially dangerous as well as provide food and habitat for many forms of fish. Such streams also play

2277-410: A river into three rough classifications. These classifications apply to all river waters, from small streams to medium-sized and large rivers and lakes. The creek area in the upper reaches or headwaters of a water system is usually very narrow and lined by thick shore vegetation. This prevents the penetration of sunlight, in turn decreasing the production of organic material through photosynthesis in

2376-406: A slow-moving wetted channel or stagnant area. This is evidence that iron-oxidizing bacteria are present, indicating persistent expression of oxygen-depleted ground water. In a forested area, leaf and needle litter in the stream channel is an additional indicator. Accumulation of leaf litter does not occur in perennial streams since such material is continuously flushed. In the adjacent overbank of

2475-514: A small share of predators. The continuous changes down the water route are due to various factors. As described above, at its beginning, the river is very strongly influenced by material from outside the system, especially organic material which is consumed by various macroinvertebrates (mainly shredders). As you go further down the system there is an increase in autochthonous (i.e., within the system) production of organic material such as periphyton . The extent of this production varies depending on

2574-409: A species is relative to other species in a given location or community. Usually relative species abundances are described for a single trophic level . Because such species occupy the same trophic level they will potentially or actually compete for similar resources. For example, relative species abundances might describe all terrestrial birds in a forest community or all planktonic copepods in

2673-569: A species may survive in the community by carving out a portion of another species' niche (slicing up the pie into smaller pieces) or by moving into a vacant niche (essentially making the pie larger, for example, by being the first to arrive in a newly available location or through the development of a novel trait that allows access previously unavailable resources). Numerous niche apportionment models have been developed. Each make different assumptions about how species carve up niche-space. The Unified Neutral Theory of Biodiversity and Biogeography (UNTB)

2772-486: A stream as intermittent, "showing interruptions in time or space". Generally, streams that flow only during and immediately after precipitation are termed ephemeral . There is no clear demarcation between surface runoff and an ephemeral stream, and some ephemeral streams can be classed as intermittent—flow all but disappearing in the normal course of seasons but ample flow (backups) restoring stream presence — such circumstances are documented when stream beds have opened up

2871-424: A stream is a critical factor in determining its character and is entirely determined by its base level of erosion. The base level of erosion is the point at which the stream either enters the ocean, a lake or pond, or enters a stretch in which it has a much lower gradient, and may be specifically applied to any particular stretch of a stream. In geological terms, the stream will erode down through its bed to achieve

2970-524: A thin layer called sheet wash, combined with a network of tiny rills, which together form the sheet runoff; when this water is focused in a channel, a stream is born. Some rivers and streams may begin from lakes or ponds. Freshwater's primary sources are precipitation and mountain snowmelt. However, rivers typically originate in the highlands, and are slowly created by the erosion of mountain snowmelt into lakes or rivers. Rivers usually flow from their source topographically, and erode as they pass until they reach

3069-627: A vital role in preserving our drinking water quality and supply, ensuring a steady flow of water to surface waters and helping to restore deep aquifers. The extent of land basin drained by a stream is termed its drainage basin (also known in North America as the watershed and, in British English, as a catchment). A basin may also be composed of smaller basins. For instance, the Continental Divide in North America divides

River Continuum Concept - Misplaced Pages Continue

3168-449: Is zero-sum as there are a limited number of spaces that can be occupied: an increase in the number of individuals of one species in the grid must result in corresponding decrease in the number of individuals of other species in the grid. The model then uses birth, death, immigration, extinction and speciation to modify community composition over time. The UNTB model produces a dimensionless "fundamental biodiversity" number,  θ , which

3267-533: Is a special form of mechanistic model that takes an entirely different approach to community composition than the niche apportionment models. Instead of species populations reaching equilibrium within a community, the UNTB model is dynamic, allowing for continuing changes in relative species abundances through drift. A community in the UNTB model can be best visualized as a grid with a certain number of spaces, each occupied with individuals of different species. The model

3366-435: Is a stream that branches off and flows away from a main stream channel, and the phenomenon is known as river bifurcation . Distributaries are common features of river deltas , and are often found where a valleyed stream enters wide flatlands or approaches the coastal plains around a lake or an ocean . They can also occur inland, on alluvial fans , or where a tributary stream bifurcates as it nears its confluence with

3465-462: Is added, it is used or stored, with a small proportion making its way further downstream. The existing energy is the limiting growth factor of the system, therefore the system is striving to be as efficient as possible. Free resources will enable new types of life in the community to establish, so that the excess resources are quickly exploited. This principle is not exclusively for river ecosystems but applies to most systems. Here, however, it plays

3564-819: Is based on the physical geomorphological theory, structural and functional characteristics of stream communities are selected to conform to the most probable position or mean state of the physical system. As a river changes from headwaters to the lower reaches, there will be a change in the relationship between the production and consumption (respiration) of the material (P/R ratio). The four scientists who collaborated with Dr. Vannote were Drs. G.Wayne Minshall (Idaho State University), Kenneth W. Cummins (Michigan State University), James R. Sedell (Oregon State University), and Colbert E. Cushing (Battelle-Pacific Northwest Laboratory). The group studied stream and river ecosystems in their respective geographical areas to support or disprove tenets of their original theory. The research resulted in

3663-409: Is derived using the formula: where : Relative species abundances in the UNTB model follow a zero-sum multinomial distribution. The shape of this distribution is a function of the immigration rate, the size of the sampled community (grid), and  θ . When the value of θ is small, the relative species abundance distribution is similar to the geometric series (high dominance). As θ gets larger,

3762-420: Is pushed farther to the left and more of the normal curve becomes visible (Figure 6). Williams' moth data, originally used by Fisher to develop the logseries distribution, became increasingly lognormal as more years of sampling were completed. Preston's theory has an application: if a community is truly lognormal yet under-sampled, the lognormal distribution can be used to estimate the true species richness of

3861-425: Is sometimes termed a "young" or "immature" stream, and the later state a "mature" or "old" stream. Meanders are looping changes of direction of a stream caused by the erosion and deposition of bank materials. These are typically serpentine in form. Typically, over time the meanders gradually migrate downstream. If some resistant material slows or stops the downstream movement of a meander, a stream may erode through

3960-456: Is usually called a creek and marked on topographic maps with a solid blue line. There are five generic classifications: "Macroinvertebrate" refers to easily seen invertebrates , larger than 0.5 mm, found in stream and river bottoms. Macroinvertebrates are larval stages of most aquatic insects and their presence is a good indicator that the stream is perennial. Larvae of caddisflies , mayflies , stoneflies , and damselflies require

4059-691: The Tombigbee River basin. Continuing in this vein, a component of the Mississippi River basin is the Ohio River basin, which in turn includes the Kentucky River basin, and so forth. Stream crossings are where streams are crossed by roads , pipelines , railways , or any other thing which might restrict the flow of the stream in ordinary or flood conditions. Any structure over or in a stream which results in limitations on

River Continuum Concept - Misplaced Pages Continue

4158-480: The velocity of the stream. A perennial stream is one which flows continuously all year. Some perennial streams may only have continuous flow in segments of its stream bed year round during years of normal rainfall. Blue-line streams are perennial streams and are marked on topographic maps with a solid blue line. The word "perennial" from the 1640s, meaning "evergreen," is established in Latin perennis, keeping

4257-419: The x -axis are increasingly rare, they may be missed in a random species sample. As the sample size increases however, the likelihood of collecting rare species in a way that accurately represents their abundance also increases, and more of the normal distribution becomes visible. The point at which rare species cease to be sampled has been termed Preston's veil line . As the sample size increases Preston's veil

4356-599: The 1980 concept was part of a two-day conference at Stroud Water Research Center, whose head director was Robin Vannote. It was the result of a multi-year study conducted by the Rockefeller Foundation . The publication of the hypothesis was released later that same year under the title "The River Continuum Concept" in the Canadian Journal of Fisheries and Aquatic Sciences. The concept built on

4455-868: The Amazon River. Science 207:1348-1351. 10. Naiman, R.J. and J.R. Sedell. 1979. Benthic organic matter as a function of stream order in Oregon. Arch. Hydrobiol. 87:404-432. 11. Naiman, R.J. and J.R. Sedell. 1980. Relationships between metabolic parameters and stream order in Oregon. Can. J. Fish. Aquat. Sci. 37:834-847. 12. Hawkins, C.P. and J.R. Sedell. 1981. Longitudinal and seasonal changes in functional organization of macroinvertebrate communities in four Oregon streams. Ecology 62:387-397. 13. Cummins, K.W., M.J. Klug, G.M. Ward, G.L. Spengler, R.W. Speaker, R.W. Ovink, D.C. Mahan, and R.C. Petersen. 1981. Trends in particulate organic matter fluxes, community processes and macroinvertebrate functional groups along

4554-704: The Caribbean (for instance, Guinea Gut , Fish Bay Gut , Cob Gut , Battery Gut and other rivers and streams in the United States Virgin Islands , in Jamaica (Sandy Gut, Bens Gut River, White Gut River), and in many streams and creeks of the Dutch Caribbean ). A river is a large natural stream that is much wider and deeper than a creek and not easily fordable, and may be a navigable waterway . The linear channel between

4653-1608: The Middle Fork of the Salmon River, Idaho. Freshwat. Invertebr. Biol. 1:2-12. 19. Cushing, C.E., K.W. Cummins, G.W. Minshall, and R.L. Vannote. 1983. Periphyton, chlorophyll a and diatoms of the Middle Fork of the Salmon River, Idaho. Holarc. Ecol. 6:221-227. 20. Minshall, G.W., R.C. Petersen, K.W. Cummins, T.L. Bott, J.R. Sedell, C.E. Cushing, and R.L. Vannote. 1983. Interbiome comparison of stream ecosystem dynamics. Ecol. Mongr. 53:1-25. 21. Bott, T.L. 1983. Primary productivity in streams, pp. 29–53. In: J.R. Barnes and G.W. Minshall (eds.) Stream Ecology: application and testing of general ecological theory. Plenum Press, N.Y. 22. Cummins, K.W., J.R. Sedell, F.J. Swanson, G.W. Minshall, S.G. Fisher, C.E. Cushing, R.C. Petersen, and R.L. Vannote. 1983. Organic matter budgets for stream ecosystems: problems in their evaluation, pp. 299–353. In: J.R. Barnes and G.W. Minshall (eds.). Stream Ecology: application and testing of general ecological theory. Plenum Press, N.Y. 23. Bruns, D.A. and G.W. Minshall. 1983 Macroscopic models of community organization: analyses of diversity, dominance, and stability in guilds of predaceous stream insects, pp. 231–264. In: J.R. Barnes and G.W. Minshall (eds.). Stream Ecology: application and testing of general ecological theory. Plenum Press, N.Y. 24. Bruns, D.A., G.W. Minshall, C.E. Cushing, K.W. Cummins, J.T. Brock, and R.L. Vannote. 1984. Tributaries as modifiers of

4752-622: The Serial Discontinuity Concept in 1983, which addresses the impact of geomorphologic disorders such as congestion and integrated inflows. The same authors presented the Hyporheic Corridor concept in 1993, in which the vertical (in depth) and lateral (from shore to shore) structural complexity of the river were connected. The flood pulse concept , developed by W.J. Junk in 1989, further modified by P.B. Bayley in 1990 and K. Tockner in 2000, takes into account

4851-421: The amount of sunlight present. The last area is less dependent on the outside but still very much influenced by the degradation processes. In a continuous system without interference, such as by inflows, this development is possible in all river systems, with some variations occurring due to seasonal changes and other environmental factors (especially temperature). At any point in the system when organic material

4950-410: The area. Relative species abundances tend to conform to specific patterns that are among the best-known and most-studied patterns in macroecology . Different populations in a community exist in relative proportions; this idea is known as relative abundance. Relative species abundance and species richness describe key elements of biodiversity . Relative species abundance refers to how common or rare

5049-533: The atmosphere either by evaporation from soil and water bodies, or by plant evapotranspiration. By infiltration some of the water sinks into the earth and becomes groundwater, much of which eventually enters streams. Most precipitated water is partially bottled up by evaporation or freezing in snow fields and glaciers. The majority of the water flows as a runoff from the ground; the proportion of this varies depending on several factors, such as climate, temperature, vegetation, types of rock, and relief. This runoff begins as

SECTION 50

#1732765716772

5148-525: The base level of erosion throughout its course. If this base level is low, then the stream will rapidly cut through underlying strata and have a steep gradient, and if the base level is relatively high, then the stream will form a flood plain and meander. Typically, streams are said to have a particular elevation profile , beginning with steep gradients, no flood plain, and little shifting of channels, eventually evolving into streams with low gradients, wide flood plains, and extensive meanders. The initial stage

5247-597: The base stage of erosion. The scientists have offered a way based on data to define the origin of the lake. A classified sample was the one measured by the Chinese researchers from the University of Chinese Academy of Sciences. As an essential symbol of the river formation environment, the river source needs an objective and straightforward and effective method of judging . A calculation model of river source catchment area based on critical support flow (CSD) proposed, and

5346-574: The curves illustrated in Figure 4. Researchers attempting to understand relative species abundance patterns usually approach them in a descriptive or mechanistic way. Using a descriptive approach biologists attempt to fit a mathematical model to real data sets and infer the underlying biological principles at work from the model parameters. By contrast, mechanistic approaches create a mathematical model based on biological principles and then test how well these models fit real data sets. I. Motomura developed

5445-461: The derivation of the logseries is varied however Fisher proposed that sampled species abundances would follow a negative binomial from which the zero abundance class (species too rare to be sampled) was eliminated. He also assumed that the total number of species in a community was infinite. Together, this produced the logseries distribution (Figure 4). The logseries predicts the number of species at different levels of abundance ( n individuals) with

5544-415: The distribution becomes increasingly s-shaped (log-normal) and, as it approaches infinity, the curve becomes flat (the community has infinite diversity and species abundances of one). Finally, when θ  = 0 the community described consists of only one species (extreme dominance). An unexpected result of the UNTB is that at very large sample sizes, predicted relative species abundance curves describe

5643-552: The distribution of individuals among species within a trophic level. Relative species abundance distributions are usually graphed as frequency histograms ("Preston plots"; Figure 2) or rank-abundance diagrams ("Whittaker Plots"; Figure 3). Frequency histogram (Preston plot) : Rank-abundance diagram (Whittaker plot) : When plotted in these ways, relative species abundances from wildly different data sets show similar patterns: frequency histograms tend to be right-skewed (e.g. Figure 2) and rank-abundance diagrams tend to conform to

5742-439: The equivalent probability of giving rise to new species or becoming extinct. As the number of species within a genus, within a clade, has a similar distribution to the number of individuals within a species, within a community (i.e. the "hollow curve"), Sean Nee (2003) used the model to describe relative species abundances. In many ways this model is similar to niche apportionment models , however, Nee intentionally did not propose

5841-458: The even distribution is that predators are not dependent on the size of the organic matter but on the availability of prey animals in the area. Atypical changes in the composition of these groups of organisms within a watercourse, such as an increased number of choppers in a major river area (mid to lower reach) or a lack of these organisms in the upper reaches, suggest a possible disturbance. The River Continuum Concept assigns different sections of

5940-707: The flow is reduced to a trickle or less. Typically torrents have Apennine rather than Alpine sources, and in the summer they are fed by little precipitation and no melting snow. In this case the maximum discharge will be during the spring and autumn. An intermittent stream can also be called a winterbourne in Britain, a wadi in the Arabic -speaking world or torrente or rambla (this last one from arabic origin) in Spain and Latin America. In Australia, an intermittent stream

6039-447: The form of rain and snow. Most of this precipitated water re-enters the atmosphere by evaporation from soil and water bodies, or by the evapotranspiration of plants. Some of the water proceeds to sink into the earth by infiltration and becomes groundwater, much of which eventually enters streams. Some precipitated water is temporarily locked up in snow fields and glaciers , to be released later by evaporation or melting. The rest of

SECTION 60

#1732765716772

6138-658: The formula: where: The number of species with 1, 2, 3, ..., n individuals are therefore: The constants α and x can be estimated through iteration from a given species data set using the values S and N . Fisher's dimensionless α is often used as a measure of biodiversity, and indeed has recently been found to represent the fundamental biodiversity parameter θ from neutral theory ( see below ). Using several data sets (including breeding bird surveys from New York and Pennsylvania and moth collections from Maine, Alberta and Saskatchewan) Frank W. Preston (1948) argued that species abundances (when binned logarithmically in

6237-412: The geometric series model based on benthic community data in a lake. Within the geometric series each species' level of abundance is a sequential, constant proportion ( k ) of the total number of individuals in the community. Thus if k is 0.5, the most common species would represent half of individuals in the community (50%), the second most common species would represent half of the remaining half (25%),

6336-407: The immediate vicinity of a stream is called a riparian zone . Given the status of the ongoing Holocene extinction , streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity . The study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography . A brook is a stream smaller than

6435-532: The lake has significant feeder rivers. The Kagera River, which flows into Lake Victoria near Bukoba's Tanzanian town , is the longest feeder, though sources do not agree on which is the Kagera's longest tributary and therefore the Nile's most remote source itself. To qualify as a stream, a body of water must be either recurring or perennial. Recurring (intermittent) streams have water in the channel for at least part of

6534-799: The large amount of nutrients and organic material that makes its way into a river from the sediment of surrounding flooded land. ATTACHMENT Publications from the original RCC studies: 1. Vannote, R.L., G.W. Minshall, K.W. Cummins, J.R. Sedell, and C.E. Cushing. 1980. The river continuum concept. Can. J. Fish. Aquat. Sci. 37:130-137. 2. Bott, T.L., J.T. Brock, C.E. Cushing, S.V. Gregory, D. King, and R.C. Petersen. 1978. A comparison of methods for measuring primary productivity and community respiration in streams. Hydrobiologia 60:3-12. 3. Cummins, K.W. 1977. From headwater streams to rivers. Amer. Biol. Teacher 39:305-312. 4. Sedell, J.R., R.J. Naiman, K.W. Cummins, G.W. Minshall, and R.L. Vannote. 1978. Transport of particulate organic material in streams as

6633-479: The left of the veil line) is simply N minus the number of species sampled. Preston did this for two lepidopteran data sets, predicting that, even after 22 years of collection, only 72% and 88% of the species present had been sampled. The Yule model is based on a much earlier, Galton–Watson model which was used to describe the distribution of species among genera . The Yule model assumes random branching of species trees, with each species (branch tip) having

6732-683: The mainly easterly-draining Atlantic Ocean and Arctic Ocean basins from the largely westerly-flowing Pacific Ocean basin. The Atlantic Ocean basin, however, may be further subdivided into the Atlantic Ocean and Gulf of Mexico drainages. (This delineation is termed the Eastern Continental Divide .) Similarly, the Gulf of Mexico basin may be divided into the Mississippi River basin and several smaller basins, such as

6831-599: The majority of resources. The geometric series model fits observed species abundances in highly uneven communities with low diversity. This is expected to occur in terrestrial plant communities (as these assemblages often show strong dominance) as well as communities at early successional stages and those in harsh or isolated environments (Figure 5). where : The logseries was developed by Ronald Fisher to fit two different abundance data sets: British moth species (collected by Carrington Williams ) and Malaya butterflies (collected by Alexander Steven Corbet ). The logic behind

6930-412: The meaning as "everlasting all year round," per "over" plus annus "year." This has been proved since the 1670s by the "living years" in the sense of botany. The metaphorical sense of "enduring, eternal" originates from 1750. They are related to "perennial." See biennial for shifts in vowels. Perennial streams have one or more of these characteristics: Absence of such characteristics supports classifying

7029-436: The midreaches of a river, river structures such as rocks and trees play an important role as a supplier of organic material such as periphyton and other autochthonous organic materials. The photosynthesis to respiration ratio is larger in this section and amounts to P: R> 1. The percentage of shredders in this area is less than that of the headwaters, due to lack of coarse plant particulate. Collectors and grazers make up

7128-415: The most affected by daily periodic changes, because here there is the greatest biodiversity , each with different ideal conditions. Because there is a uniform use of resources and high stability, disturbances and fluctuations are usually corrected relatively quickly. Inequalities in the use of resources will be quickly compensated for, creating a new equilibrium. Also, there is no ecological development of

7227-401: The movement of fish or other ecological elements may be an issue. Species composition Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community. Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in

7326-453: The neck between two legs of a meander to become temporarily straighter, leaving behind an arc-shaped body of water termed an oxbow lake or bayou . A flood may also cause a meander to be cut through in this way. The stream load is defined as the solid matter carried by a stream. Streams can carry sediment, or alluvium. The amount of load it can carry (capacity) as well as the largest object it can carry (competence) are both dependent on

7425-649: The organic matter along with volunteer organisms (fungi, microorganisms) attached to the source. The preferred size of the CPOM is about one millimeter, therefore shredders must break it up into a finer particulate. In the process of shredding, much of the now finer organic matter is left in the system, making its way further downstream. Some common shredders of North American waters include the Mayfly ( Ephemeroptera ), Odonata (damselflies) and stone fly ( Plecoptera ) larvae, whereas decapods (particularly Atyid shrimp ) fulfill

7524-596: The origin of the Nile River is the confluence of the White Nile and the Blue Nile, but the source of the whole river system is in its upper reaches. If there is no specific designation, "length of the Nile" refers to the "river length of the Nile system", rather than to the length of the Nile river from the point where it is formed by a confluence of tributaries. The Nile's source is often cited as Lake Victoria, but

7623-571: The original RCC. The continuous differences of properties within the river are dependent primarily on the specific composition of the organisms in different sections of the water. Throughout the continuum of the river, the proportion of the four major food types; shredders, collectors, grazers (scrapers) and predators change. With the exception of the predators, all these organisms feed directly from plant material (saprobes). Shredders are organisms that feed off of coarse particulate organic material (CPOM) such as small sections of leaves. They ingest

7722-430: The other hand, has a relatively constant input and is controlled more by long-term patterns of precipitation. The stream encompasses surface, subsurface and groundwater fluxes that respond to geological, geomorphological, hydrological and biotic controls. Streams are important as conduits in the water cycle , instruments in groundwater recharge , and corridors for fish and wildlife migration. The biological habitat in

7821-415: The parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Also called a swale . A tributary is a contributory stream to a larger stream, or a stream which does not reach a static body of water such as a lake , bay or ocean but joins another river (a parent river). Sometimes also called a branch or fork. A distributary , or a distributary channel ,

7920-589: The presence of periphyton. Shredders only make up a small percentage of the total invertebrates due to the lack of coarse organic matter making its way downstream. In the lower reaches, organic matter has been shredded completely to the level of FPOM or UPOM (Ultra-fine Particulate Organic Matter). Due to the increase in fine particulate organic matter, collectors are the most abundant in the lower reaches, feeding off organic matter and surface films. The proportion of predators in all sections remains largely constant and only changes in species composition . The reason for

8019-761: The publication of 33 scientific papers (see attachment to Bibliography). The original 1980 paper received the John Martin Award from the Association for the Sciences of Limnology and Oceanography (formerly the American Society of Limnology and Oceanography) that recognizes papers still relevant ten years after their publication. Subsequent research related to the RCC by these scientists has resulted in several more scientific papers that amplify parts of

8118-469: The relationship between CSA and CSD with a minimum catchment area established. Using the model for comparison in two basins in Tibet (Helongqu and Niyang River White Water), the results show that the critical support flow (Qc) of the housing dragon song is 0.0028 m /s. At the same time, the white water curvature is 0.0085 m /s. Besides, the critical support flow can vary with hydrologic climate conditions, and

8217-734: The river continuum concept: analysis by polar ordination and regression models. Arch. Hydrobiol. 99:208-220. 25. Cushing, C.E. and S.R. Rushforth. 1984, Diatoms of the Middle Fork of the Salmon River drainage with notes on their relative abundance and distribution. Great Basin Nat. 44:421-427. 26. Cushing, C.E., C.D. Mcintire, K.W. Cummins, G.W. Minshall, R.C. Petersen, J.R. Sedell and R.L. Vannote. 1983. Relationships among chemical, physical, and biological indices along river continua based on multivariate analyses. Arch. Hydrobiol. 98:317-326. 27. Minshall, G.W., R.C. Petersen, Jr., and C.F. Nimz. 1985. Species richness in streams of different size from

8316-423: The same drainage basin . Amer. Nat. 125:16-38. 28. Bott, T.L., J.T. Brock, C.S.Dunn, R.J. Naiman, R.W. Ovink, and R.C. Petersen. 1985. Benthic community metabolism in four temperate stream systems: An inter-biome comparison and evaluation of the river continuum concept. Hydrobiologia 123:3-45. Watercourse A stream is a continuous body of surface water flowing within the bed and banks of

8415-575: The same trophic level consume the same resources (such as nutrients or sunlight in plant communities, prey in carnivore communities, nesting locations or food in bird communities) and these resources are limited, how the resource "pie" is divided among species determines how many individuals of each species can exist in the community. Species with access to abundant resources will have higher carrying capacities than those with little access. Mutsunori Tokeshi later elaborated niche apportionment theory to include niche filling in unexploited resource space. Thus,

8514-636: The same role in tropical environments. Collector organisms are designated by their use of traps or other adaptive features to filter and catch organic matter. The preferred particle size for collectors lies between 0.5 and 50 micrometers (UPOM = Ultrafine particulate organic matter and FPOM = fine particulate organic matter). This group includes fly larvae , nematodes , and many other animal groups. The grazers (scrapers) feed off of periphyton that accumulates on larger structures such as stones, wood or large aquatic plants. These include snails , caddisflies (Glossosoma genus), and other organisms. Because of

8613-425: The side of the stream or within the floodplain will be a good indicator of persistent water regime. A perennial stream can be identified 48 hours after a storm. Direct storm runoff usually has ceased at this point. If a stream is still flowing and contributing inflow is not observed above the channel, the observed water is likely baseflow. Another perennial stream indication is an abundance of red rust material in

8712-424: The structure of organic matter at different sections in a river, the make up and frequency of these groups in a community vary. In the upper reaches of a river, shredders and collectors make up a large percentage of total macroinvertebrates due to the excess presence of coarse plant matter. In the midreaches of a stream or river, where more light is available, there is an increase in the proportion of grazers due to

8811-413: The system (succession) and changes in the system are a result of outside geological changes, such as a change in the level of water making its way into the system, change of organic inputs or earthquakes . Even after these changes, however, it returns to a steady and modified equilibrium. This ensures that the ecosystem stays as an optimal functioning river system. The first comprehensive presentation of

8910-529: The system in its entirety. In practice, the River Continuum Concept is used today mainly for environmental assessment of rivers. River studies that assess riverine biological communities and have determined the species composition of an area can then be compared with the ideal species composition from the River Continuum Concept. From there, any variations in species composition may shed light on disturbances that might be occurring to offset

9009-508: The system. Although the River Continuum Concept is a broadly accepted theory, it is limited in its applicability. It describes a perfect and even model without taking into account changing riverine disturbances and irregularities. Disturbances such as congestion by dams or natural events such as shore flooding are not included in the model. Various researchers have since expanded the River Continuum Concept to account for such irregularities. For example, J.V. Ward and J.A. Stanford came up with

9108-425: The third, half of the remaining quarter (12.5%) and so forth. Although Motomura originally developed the model as a statistical (descriptive) means to plot observed abundances, the "discovery" of his paper by Western researchers in 1965 led to the model being used as a niche apportionment model – the "niche-preemption model". In a mechanistic model k represents the proportion of the resource base acquired by

9207-655: The vital support flow Qc in wet areas (white water) is larger than in semi-arid regions (heap slot). The proposed critical support flow (CSD) concept and model method can be used to determine the hydrographic indicators of river sources in complex geographical areas, and it can also reflect the impact of hydrologic climate change on river recharge in different regions. The source of a river or stream (its point of origin) can consist of lakes, swamps, springs, or glaciers. A typical river has several tributaries; each of these may be made up of several other smaller tributaries, so that together this stream and all its tributaries are called

9306-512: The water flows off the land as runoff, the proportion of which varies according to many factors, such as wind, humidity, vegetation, rock types, and relief. This runoff starts as a thin film called sheet wash, combined with a network of tiny rills, together constituting sheet runoff; when this water is concentrated in a channel, a stream has its birth. Some creeks may start from ponds or lakes. The streams typically derive most of their water from rain and snow precipitation. Most of this water re-enters

9405-415: The water. The majority of the organic matter that does make its way into the system is in the form allochthonous plant material that falls into the river, such as leaves and sticks. In this section, respiration (consumption) out paces production (P/R<1). Here shredders play a major role in breaking down coarse plant material. In this area, the largest diversity of organic material can be expected. In

9504-461: The work of other American limnologists such as Ruth Patrick , from which the modern riverine ecosystem model has emerged, and Luna Leopold, which deals with the physical changes of water. The essential goal of the concept was to further assess and explain the various communities in the system. Vannote himself described the current situation as follows, "in those days, most people studied a square meter of water to death ”. Meaning that previous research

9603-521: The year and is marked on topographic maps with a line of blue dashes and dots. A wash , desert wash, or arroyo is normally a dry streambed in the deserts of the American Southwest , which flows after sufficient rainfall. In Italy, an intermittent stream is termed a torrent ( Italian : torrente ). In full flood the stream may or may not be "torrential" in the dramatic sense of the word, but there will be one or more seasons in which

9702-402: The year. A stream of the first order is a stream which does not have any other recurring or perennial stream feeding into it. When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream. The gradient of

9801-519: Was always only on small pieces of water and only rarely was the entire river system considered, allowing for the creation of a general model. After its publication, the River Continuum Concept was adopted as the accepted model in the limnology community, becoming a favorite means for describing the communities living in flowing water. Here it broke the classic idea of riverine structure. Previous approaches had their disadvantages because they only described small zones of water and had no consideration for

#771228