Lo Tic
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LOTIC ECOSYSTEM STREAMS & RIVERS inherited from preexisting river; evolution through geologic time Although there are many rivers and streams,
these sources of running water account for a very small portion of the earth's total surface, just .3%. linear morphology; shallow; relatively fast flowing; longitudinal zonation stream bed (rocks/mud/detritus) - determined by interaction b/ween discharge (volume per time; m3/s) & current (distance per time) with substrate thermal stratification & chemical density is not important chemical composition is affected by their irregular discharge max discharge during rain or spring snow melt
plankton do not play a significant role in biotic structure, except in big, deep rivers upstream; - erosion effect - more particles eroded - bigger substrates downstream: - accumulation of particles - mud accumulation relatively fast flowing & high dependent to allochthonous organic matter closely link to the catchments or watersheds all biota are influenced by unidirectional current & adapted accordingly high discharges transport much of the annual load of soluble nutrients
organism distribution is limited the exchange of material b/ween soil & water is faster dissolved oxygen is high in the fast flowing waters salt content increase towards the river mouth (estuary) lotic ecosystem combine the chemical & physical aspects with biotic interactions rivers and streams form a network of waterways across the countryside. the network of rivers and streams form a
watershed which drains the land of excess water.
A Lateral View Across the Stream Corridor The focus here is on structural features or zones that one encounters moving across the stream. Lateral structure of the corridor affects the movement of water, materials, energy, and organisms from upland areas into the stream channel. A Longitudinal View Along the Stream Corridor This section takes a view of structure along the stream corridor's whole length from its headwaters to mouth. It includes discussions of channel form, sediment transport and deposition, and how biological communities have adapted to different stages of the river continuum
Stream Corridor Structure: A Lateral View three major components in cross section : i. Stream channel, a channel with flowing water at least part of the year. ii. Floodplain, a highly variable area on one or both sides of the stream channel that is inundated by floodwaters at some interval, from frequent to rare. iii. Transitional upland fringe, a portion of the upland on the landward side of the floodplain that serves as a transitional zone or edge between the floodplain and the surrounding landscape
In this example, the floodplain is seasonally inundated (flood) and includes features such as floodplain forest, emergent marshes and wet meadows. This river's transitional upland fringe includes an upland forest and a hill prairie. Landforms such as natural levees are created by processes of erosion and sedimentation, primarily during floods. The various plant communities possess unique moisture tolerances and requirements, and consequently occupy distinct positions relative to the stream.
Streamflow The two basic components are: 1. Stormflow: from precipitation that reaches the channel over a short time frame through overland or underground routes.
2. Baseflow : from precipitation that percolates (filtrate) to the ground water and moves slowly through substrate before reaching the channel. It sustains (support) streamflow during periods of little or no precipitation.
Changes in hydrology after urbanization The hydrology (study of water movmt) of urban streams changes as sites are cleared and natural vegetation is replaced by impervious cover more of a stream's annual flow is delivered as storm water runoff rather than baseflow. since impervious cover prevents rainfall from infiltrating into the soil, less flow is available to recharge ground water. Therefore, during extended periods without rainfall, baseflow levels are often reduced in urban streams (Simmons and Reynolds 1982).
Stream managers categorize streams based on the balance and timing of the stormflow and baseflow components. There are three main categories: Ephemeral streams flow only during or immediately after periods of precipitation. They generally flow less than 30 days per year.
Intermittent streams flow only during certain times of the year. Seasonal flow in an intermittent stream usually lasts longer than 30 days per year. Perennial streams flow continuously during both wet and dry times. Baseflow is dependably generated from the movement of ground water into the channel.
Ephemeral streams in Antarctica
Plate 3.1: The upper runnel area with the adjacent snow bank (a) as the only source of water to the shallow pool; (b) indicates the building of Casey Station located about 500 meters from the sampling area.
Plate 3.2: The earlier part of the middle runnel which indicates the presence of rocks aligning the streambed.
streamflow is one of the variables that determine the size and shape of the channel. Discharge, Q (volume per time; m3/s) Q=AV where: Q = Discharge A = Area through which the water is flowing in square feet V = Average velocity in the downstream direction in feet per second
Flood-Pulse Concept
demonstrates how flooding processes, plants and wildlife in all parts of the stream corridor interact Floodplains serve as essential focal points for the growth of many riparian (river bank) plant communities and the wildlife they support. Flooding also nourishes floodplains with sediments and nutrients and provides habitat for invertebrate communities, amphibians, reptiles, and fish spawning (produce egg). The flood-pulse concept was developed to summarize how the dynamic interaction between water and land is exploited by the aquatic and terrestrial river corridor biota. Applicable primarily on larger rivers, the concept demonstrates that the predictable advance and retraction of water on the floodplain in a natural setting enhances biological productivity and maintains diversity (Bayley 1995).
What Is A Watershed? A watershed describes an area of land that contains a common set of streams and rivers that all drain into a single larger body of water, such as a larger river, a lake or an ocean. All the streams flowing into small rivers, larger rivers, and eventually into the ocean, form an interconnecting network of waterways. Not only does water run into the streams and rivers from the surface of a watershed, but water also filters through the soil, and some of this water eventually drains into the same streams and rivers. The network of streams and rivers that drain the watershed and carry water pollution ultimately empty into larger bodies of water, such as lakes and oceans. Through watersheds, pollution is distributed far away from its original source.
Drainage basin/watershed/basin/catchment
Stream order
Generally, the smallest streams in a watershed that have year-round water and no tributaries (flowing) are termed "first order" streams. When two first order streams come together, they form a "second order" stream and when two second order streams come together, they form a "third order" stream. This process then continues on down the drainage network until the large river meets an ocean.
Riparian Corridors important landscape elements for ecosystem function lie at the interface terrestrial and aquatic ecosystems, and control/influence substantial flows of energy and matter between them The physical processes of stream and floodplain formation processes underpin the ecosystem function or riparian zones. The longitudinal (along stream) and latitudinal (cross stream) structure of the riparian corridor is substantially established by stream and floodplain formation processes and reflects very definite spatial patterns in aquatic and terrestrial ecosystem processes
Vegetation Across the Stream Corridor The distribution of these communities would be based on different hydrologic and soil conditions. Plant communities play a significant role in determining stream corridor condition, vulnerability (damage), and potential for (or lack of) restoration. the type, extent and distribution, soil moisture preferences, elevation, species composition, age, vigor, and rooting depth are all important characteristics that must be considered when planning and designing stream corridor restoration.
• deeper pools are separated by riffles of shallow, turbulent water passing through or over stones or gravel Riffles: • contain the majority of the stream’s benthic invertebrates • stones covered with algae & mosses – main in situ 1º producers Pools: • less dense biota living among a mixture of stones & fine-grain sediments • accumulation of decaying terrestrial debris
2. Stream Corridor Structure: Longitudinal Zones
Zone 1, or headwaters: • often has the steepest gradient • Sediment erodes from slopes of the watershed and moves downstream. • low T; allochthonous organic matter • neuston distribution is not important; plankton doesn’t play an important role in biotic structure Zone 2, the transfer zone : • receives some of the eroded material • characterized by wide floodplains and meandering channel patterns Zone 3, the primary depositional zone. : • neuston population high • phytoplankton & benthos
RIVER CONTINUUM CONCEPT In general width, depth, temperature, and discharge increase further downstream. The River Continuum Concept seeks to correlate this continuum of physical changes with biological changes throughout a river system and provides a conceptual model to compare with stream systems throughout the world. Aquatic macroinvertebrates play important roles in the food webs of the stream ecosystem Macroinvertebrates can be classified not only by traditional taxonomy but also by how they function in the ecosystem. This method of classification based on feeding adaptations and/or food preferences is known as functional feeding groups.
The River Continuum Concept describes the physical processes (geology, climate) outside of a river that effect the biological processes (vegetation) along a river, which effect the physical and biological processes within a river (temperature, nutrients). The River Continuum Concept states that producer and consumer communities become established in harmony with the dynamic physical conditions that include width, depth, velocity, flow volume, and temperature of the river (Vannote et al.). Based on: vi. Stream order vii.Type of organic particle viii.Type of benthic invertebrate Networks of streams in the drainage basin forms a continuum of physical gradients & associated biotic adjustment The structure & function of the benthic invertebrate community is strongly regulated by the gradients of allochthonous & autochthonous organic matter
Food web in small stream
Figure 1. Food web in = small streams
The relative importance of the major functional invertebrate groups gradually changes downstream with the food supply
Functional Feeding Groups
Feeding Strategy
Food Category
I.
Shredders
dead leaves/live macrophytes
II.
Collectors
fine organic particles (live/dead) filter feeders
particles in water column
miners
buried particles
browsers
bottom surface deposits
III.
Scrapers
live benthic algae (diatoms)
IV.
Piercers
live filamentous algae
V.
Predators
other invertebrates + small fish
Shredders and collectors form the major proportion of stream macroinvertebrates Leaves accumulate in leaf packs in streams. The animals adapted to feeding on leaves are called "shredders." Shredders get nutrition primarily from the fungi and bacteria that colonize the leaf surface. Small fragments of leaves and feces from shredders are captured by another group of macroinvertebrates called collectors.
Collectors gather or filter plant fragments, feces, and plankton. Grazers, also known as Scrapers browse on algae.
in-stream photosynthesis plays a more important role. Leaf litter reaching the stream decreases and algae, due to the increased sunlight, becomes more abundant. As the food base shifts so does the type of invertebrates Grazers/Scrapers who utilize the abundant algal resource increase while shredders decrease Snails, limpets, certain mayflies and case-building caddisflies are adapted to feeding on the algae growing on rock surfaces.
Trees shade only the edge of the river and sunlight, although abundant, does not penetrate to the river's bottom due to turbidity. The food base is dominated by phytoplankton and fine, suspended organic particles generated further upstream and from the river's floodplain. Filtering collectors such as mussels and clams are adapted to filtering these fine particles from the water column. To complete food web ecology, a diverse group of predators are found throughout the entire stream length feeding on all other feeding groups.
a)
old fish based zonatation
grazingminnow reach
trout reach
barbelpearch reach
carp-bream reach
100
b)
COLLECTORS (eg midge larvae)
75 Percentage of total invertebrates population
50
SHREDDERS (eg crayfish)
GRAZERS( eg snail) PREDATORS (e.g stone flies)
25
0 1
2
3
4
5
6
7
8
9
10 11 12
STREAM/RIVER ORDER
The river continuum concept. (a) The older concept based on typical fish (b) An idealized repersentation of the relative abundance of types of benthic invertebrates (collectors, shredders, grazers and predators) from headwater to river mouth.
STREAM/RIVER WIDTH (m)
0.5
1.5
Entire leaves, twigs (CPOM)
1.0
5
10
60
Nutritious leaf fragments (CPOM+FPOM)
700
Refractory, undigestable leaf remains (FPOM+DOM)
Ratio FPOM CPOM 0.1
0.01
1
2
3
4
5
6
7
8
9 10 11 12
c) The ratio of CPOM to FPOM increasing downstream as entire leaves, twigs, fruits are eaten & recycled by the invertebrates & microbes
CPOM: > 1mm FPOM: < 1mm
these sources of running water account for a very small portion of the earth's total surface, just .3%. linear morphology; shallow; relatively fast flowing; longitudinal zonation stream bed (rocks/mud/detritus) - determined by interaction b/ween discharge (volume per time; m3/s) & current (distance per time) with substrate thermal stratification & chemical density is not important chemical composition is affected by their irregular discharge max discharge during rain or spring snow melt
plankton do not play a significant role in biotic structure, except in big, deep rivers upstream; - erosion effect - more particles eroded - bigger substrates downstream: - accumulation of particles - mud accumulation relatively fast flowing & high dependent to allochthonous organic matter closely link to the catchments or watersheds all biota are influenced by unidirectional current & adapted accordingly high discharges transport much of the annual load of soluble nutrients
organism distribution is limited the exchange of material b/ween soil & water is faster dissolved oxygen is high in the fast flowing waters salt content increase towards the river mouth (estuary) lotic ecosystem combine the chemical & physical aspects with biotic interactions rivers and streams form a network of waterways across the countryside. the network of rivers and streams form a
watershed which drains the land of excess water.
A Lateral View Across the Stream Corridor The focus here is on structural features or zones that one encounters moving across the stream. Lateral structure of the corridor affects the movement of water, materials, energy, and organisms from upland areas into the stream channel. A Longitudinal View Along the Stream Corridor This section takes a view of structure along the stream corridor's whole length from its headwaters to mouth. It includes discussions of channel form, sediment transport and deposition, and how biological communities have adapted to different stages of the river continuum
Stream Corridor Structure: A Lateral View three major components in cross section : i. Stream channel, a channel with flowing water at least part of the year. ii. Floodplain, a highly variable area on one or both sides of the stream channel that is inundated by floodwaters at some interval, from frequent to rare. iii. Transitional upland fringe, a portion of the upland on the landward side of the floodplain that serves as a transitional zone or edge between the floodplain and the surrounding landscape
In this example, the floodplain is seasonally inundated (flood) and includes features such as floodplain forest, emergent marshes and wet meadows. This river's transitional upland fringe includes an upland forest and a hill prairie. Landforms such as natural levees are created by processes of erosion and sedimentation, primarily during floods. The various plant communities possess unique moisture tolerances and requirements, and consequently occupy distinct positions relative to the stream.
Streamflow The two basic components are: 1. Stormflow: from precipitation that reaches the channel over a short time frame through overland or underground routes.
2. Baseflow : from precipitation that percolates (filtrate) to the ground water and moves slowly through substrate before reaching the channel. It sustains (support) streamflow during periods of little or no precipitation.
Changes in hydrology after urbanization The hydrology (study of water movmt) of urban streams changes as sites are cleared and natural vegetation is replaced by impervious cover more of a stream's annual flow is delivered as storm water runoff rather than baseflow. since impervious cover prevents rainfall from infiltrating into the soil, less flow is available to recharge ground water. Therefore, during extended periods without rainfall, baseflow levels are often reduced in urban streams (Simmons and Reynolds 1982).
Stream managers categorize streams based on the balance and timing of the stormflow and baseflow components. There are three main categories: Ephemeral streams flow only during or immediately after periods of precipitation. They generally flow less than 30 days per year.
Intermittent streams flow only during certain times of the year. Seasonal flow in an intermittent stream usually lasts longer than 30 days per year. Perennial streams flow continuously during both wet and dry times. Baseflow is dependably generated from the movement of ground water into the channel.
Ephemeral streams in Antarctica
Plate 3.1: The upper runnel area with the adjacent snow bank (a) as the only source of water to the shallow pool; (b) indicates the building of Casey Station located about 500 meters from the sampling area.
Plate 3.2: The earlier part of the middle runnel which indicates the presence of rocks aligning the streambed.
streamflow is one of the variables that determine the size and shape of the channel. Discharge, Q (volume per time; m3/s) Q=AV where: Q = Discharge A = Area through which the water is flowing in square feet V = Average velocity in the downstream direction in feet per second
Flood-Pulse Concept
demonstrates how flooding processes, plants and wildlife in all parts of the stream corridor interact Floodplains serve as essential focal points for the growth of many riparian (river bank) plant communities and the wildlife they support. Flooding also nourishes floodplains with sediments and nutrients and provides habitat for invertebrate communities, amphibians, reptiles, and fish spawning (produce egg). The flood-pulse concept was developed to summarize how the dynamic interaction between water and land is exploited by the aquatic and terrestrial river corridor biota. Applicable primarily on larger rivers, the concept demonstrates that the predictable advance and retraction of water on the floodplain in a natural setting enhances biological productivity and maintains diversity (Bayley 1995).
What Is A Watershed? A watershed describes an area of land that contains a common set of streams and rivers that all drain into a single larger body of water, such as a larger river, a lake or an ocean. All the streams flowing into small rivers, larger rivers, and eventually into the ocean, form an interconnecting network of waterways. Not only does water run into the streams and rivers from the surface of a watershed, but water also filters through the soil, and some of this water eventually drains into the same streams and rivers. The network of streams and rivers that drain the watershed and carry water pollution ultimately empty into larger bodies of water, such as lakes and oceans. Through watersheds, pollution is distributed far away from its original source.
Drainage basin/watershed/basin/catchment
Stream order
Generally, the smallest streams in a watershed that have year-round water and no tributaries (flowing) are termed "first order" streams. When two first order streams come together, they form a "second order" stream and when two second order streams come together, they form a "third order" stream. This process then continues on down the drainage network until the large river meets an ocean.
Riparian Corridors important landscape elements for ecosystem function lie at the interface terrestrial and aquatic ecosystems, and control/influence substantial flows of energy and matter between them The physical processes of stream and floodplain formation processes underpin the ecosystem function or riparian zones. The longitudinal (along stream) and latitudinal (cross stream) structure of the riparian corridor is substantially established by stream and floodplain formation processes and reflects very definite spatial patterns in aquatic and terrestrial ecosystem processes
Vegetation Across the Stream Corridor The distribution of these communities would be based on different hydrologic and soil conditions. Plant communities play a significant role in determining stream corridor condition, vulnerability (damage), and potential for (or lack of) restoration. the type, extent and distribution, soil moisture preferences, elevation, species composition, age, vigor, and rooting depth are all important characteristics that must be considered when planning and designing stream corridor restoration.
• deeper pools are separated by riffles of shallow, turbulent water passing through or over stones or gravel Riffles: • contain the majority of the stream’s benthic invertebrates • stones covered with algae & mosses – main in situ 1º producers Pools: • less dense biota living among a mixture of stones & fine-grain sediments • accumulation of decaying terrestrial debris
2. Stream Corridor Structure: Longitudinal Zones
Zone 1, or headwaters: • often has the steepest gradient • Sediment erodes from slopes of the watershed and moves downstream. • low T; allochthonous organic matter • neuston distribution is not important; plankton doesn’t play an important role in biotic structure Zone 2, the transfer zone : • receives some of the eroded material • characterized by wide floodplains and meandering channel patterns Zone 3, the primary depositional zone. : • neuston population high • phytoplankton & benthos
RIVER CONTINUUM CONCEPT In general width, depth, temperature, and discharge increase further downstream. The River Continuum Concept seeks to correlate this continuum of physical changes with biological changes throughout a river system and provides a conceptual model to compare with stream systems throughout the world. Aquatic macroinvertebrates play important roles in the food webs of the stream ecosystem Macroinvertebrates can be classified not only by traditional taxonomy but also by how they function in the ecosystem. This method of classification based on feeding adaptations and/or food preferences is known as functional feeding groups.
The River Continuum Concept describes the physical processes (geology, climate) outside of a river that effect the biological processes (vegetation) along a river, which effect the physical and biological processes within a river (temperature, nutrients). The River Continuum Concept states that producer and consumer communities become established in harmony with the dynamic physical conditions that include width, depth, velocity, flow volume, and temperature of the river (Vannote et al.). Based on: vi. Stream order vii.Type of organic particle viii.Type of benthic invertebrate Networks of streams in the drainage basin forms a continuum of physical gradients & associated biotic adjustment The structure & function of the benthic invertebrate community is strongly regulated by the gradients of allochthonous & autochthonous organic matter
Food web in small stream
Figure 1. Food web in = small streams
The relative importance of the major functional invertebrate groups gradually changes downstream with the food supply
Functional Feeding Groups
Feeding Strategy
Food Category
I.
Shredders
dead leaves/live macrophytes
II.
Collectors
fine organic particles (live/dead) filter feeders
particles in water column
miners
buried particles
browsers
bottom surface deposits
III.
Scrapers
live benthic algae (diatoms)
IV.
Piercers
live filamentous algae
V.
Predators
other invertebrates + small fish
Shredders and collectors form the major proportion of stream macroinvertebrates Leaves accumulate in leaf packs in streams. The animals adapted to feeding on leaves are called "shredders." Shredders get nutrition primarily from the fungi and bacteria that colonize the leaf surface. Small fragments of leaves and feces from shredders are captured by another group of macroinvertebrates called collectors.
Collectors gather or filter plant fragments, feces, and plankton. Grazers, also known as Scrapers browse on algae.
in-stream photosynthesis plays a more important role. Leaf litter reaching the stream decreases and algae, due to the increased sunlight, becomes more abundant. As the food base shifts so does the type of invertebrates Grazers/Scrapers who utilize the abundant algal resource increase while shredders decrease Snails, limpets, certain mayflies and case-building caddisflies are adapted to feeding on the algae growing on rock surfaces.
Trees shade only the edge of the river and sunlight, although abundant, does not penetrate to the river's bottom due to turbidity. The food base is dominated by phytoplankton and fine, suspended organic particles generated further upstream and from the river's floodplain. Filtering collectors such as mussels and clams are adapted to filtering these fine particles from the water column. To complete food web ecology, a diverse group of predators are found throughout the entire stream length feeding on all other feeding groups.
a)
old fish based zonatation
grazingminnow reach
trout reach
barbelpearch reach
carp-bream reach
100
b)
COLLECTORS (eg midge larvae)
75 Percentage of total invertebrates population
50
SHREDDERS (eg crayfish)
GRAZERS( eg snail) PREDATORS (e.g stone flies)
25
0 1
2
3
4
5
6
7
8
9
10 11 12
STREAM/RIVER ORDER
The river continuum concept. (a) The older concept based on typical fish (b) An idealized repersentation of the relative abundance of types of benthic invertebrates (collectors, shredders, grazers and predators) from headwater to river mouth.
STREAM/RIVER WIDTH (m)
0.5
1.5
Entire leaves, twigs (CPOM)
1.0
5
10
60
Nutritious leaf fragments (CPOM+FPOM)
700
Refractory, undigestable leaf remains (FPOM+DOM)
Ratio FPOM CPOM 0.1
0.01
1
2
3
4
5
6
7
8
9 10 11 12
c) The ratio of CPOM to FPOM increasing downstream as entire leaves, twigs, fruits are eaten & recycled by the invertebrates & microbes
CPOM: > 1mm FPOM: < 1mm
