River and Riparia Ecology Flashcards

1
Q

In general, what is the River Continuum Concept?

A

Describes communities along a river (longitudinal changes) based on their structure and function.

Proposes that the gradient of physical structure and hydrology of the river, which changes from headwaters to mouth, dictates the biology of the river in consistent patterns that maintain a dynamic equilibrium.

(Vannote et al, 1980)

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2
Q

How are the components of the River Continuum Concept grouped?

A

Lotic communities are based on stream order and grouped into headwaters (orders 1-3), medium-sized stream (orders 4-6), and large rivers (orders >6).

(Vannote et al, 1980)

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3
Q

Allochthonous

A

Nutrients come from outside the water.

(BIOL 4503 notes)

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4
Q

Autochthonous

A

Nutrients come from within the water (primary productivity).

(BIOL 4503 Notes)

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5
Q

What is a river?

A

A body of water with unidirectional flow, that is sloped, and has a defined channel.

(BIOL 4503 Notes)

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6
Q

How does stream order work?

A

Higher number = bigger body of water.

Where 2 tributaries combine into one becomes the next steam order unless a smaller tributary combines into a larger one.

e.g., 1 with 1 makes 2
but
1 with 2 makes 2

(BIOL 4503 Notes)

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7
Q

What are the basic components of a river?

A

Headwaters
Tributaries
Mouth
Channel
Slope
Stream Order
Floodplain

(BIOL 4503 Notes)

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8
Q

Floodplain

A

A level area near the stream channel that is inundated during moderate flow and is constructed by the river under present climatic conditions by deposition of sediments during overbank flooding.

(Allan & Castillo, 2009)

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9
Q

Channel

A

Where the bulk of water flows through in a river.

(BIOL 4503 Notes)

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10
Q

Headwaters

A

Where river originates i.e., 1st order stream.

(BIOL 4503 Notes; ENSC 3106 Notes)

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11
Q

Tributary

A

A river or stream flowing into a larger river or lake.

(Mac Dictionary)

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12
Q

Describe how the source of nutrients changes within a river based on the River Continuum Concept.

A

Heavy shading in headwaters results in the primary form of nutrients coming from sources external to the water body (e.g., detritus) - allochthonous.

As stream size increases, the source of nutrients becomes progressively more from primary production (autochthonous) and organic transport from upstream as shading is reduced.

This transition is reflected by a change in the ratio of primary production to cellular respiration (P/R).

In headwaters P/R < 1
In medium-sized streams P/R > 1
In large rivers P/R < 1

(Vannote et al, 1980)

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13
Q

Describe how the dominance of invertebrates within a river changes based on the River Continuum Concept.

A

Dominance changes with changes of food source (i.e., with the change of nutrient supply).

Shredders and collectors are co-dominant in headwaters.

Dominance of collectors increases with stream size.

Abundance of scrapers aligns with dominance of primary productivity therefore they are most abundant in medium-sized streams.

Abundance of predators remains fairly consistent along the river.

(Vannote et al, 1980)

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14
Q

What are the functional feeding groups of invertebrates?

A

Shredders
Collectors
Scrapers (aka grazers)
Predators

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15
Q

Shredders

A

Invertebrates that eat coarse particulate organic matter such a leaf litter.

(Vannote et al, 1980)

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16
Q

Collectors

A

Invertebrates that filter their food from transport, or from sediments, which is fine and ultra-fine particulate organic matter.

(Vannote et al, 1980)

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17
Q

Scrapers aka Grazers

A

Invertebrates that eat algae from surfaces.

(Vannote et al, 1980)

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18
Q

Predators in the RCC

A

Invertebrates that eat other invertebrates including insect larvae, worms, and sometimes even very small fish, and tadpoles.

https://habitat.fisheries.org/the-importance-of-macroinvertebrates-in-freshwater-streams/

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19
Q

Describe how fish composition within a river changes based on the River Continuum Concept.

A

There’s a shift from coolwater species with low diversity in headwaters to warmwater species with high diversity towards mouth.

Most headwater species are largely invertivores. Piscivorous and invertivorous species characterize the midsized rivers and in large rivers some planktivorous species are found - reflecting the semi-lentic nature of the waters.

(Vannote et al, 1980)

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20
Q

Aside from nutrients, describe how the other abiotic factors change along a river based on the River Continuum Concept.

A

Things that increase from headwaters to mouth:

Stream order
Width
Water temperature

Things that decrease from headwaters to mouth:

Shade
Water clarity
Water velocity
Substrate size
Size of organic matter

(BIOL 4503 Notes)

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21
Q

Why do you think mid-sized streams are most diverse?

A

Because of the intermediate disturbance hypothesis.

It states that at high disturbance levels, diversity declines as mortality rises. This could apply to headwaters since they have high water velocities and a lot of shade.

It also states that at low disturbance levels, competitive exclusion reduces diversity. This could apply to the mouths of rivers given the flow is low.

At intermediate disturbance levels, a balance between disruption of competition and mortality leads to high diversity which could be what’s happening in mid-sized streams.

(BIOL 2600 Notes)

22
Q

How does the river continuum concept apply to my work?

A

I’m studying a specific section of the river so it can give me some basic insight on the community composition I should expect to find in the area I’m studying.

23
Q

Riffle

A

Fast-moving portions of the stream flowing over coarse particles of the stream bed, which increase oxygen input into the water.

(BIOL 2600 Notes)

24
Q

Backwater

A

A part of a river not reached by the current, where the water is stagnant.

(Mac Dictionary)

25
Q

Fetch

A

The distance traveled by wind or waves across open water.

(Mac Dictionary)

26
Q

Pools

A

Deeper portions of the stream where water flows more slowly over a bed of fine sediments.

(BIOL 2600 Notes)

27
Q

What are the zones of a body of freshwater? Draw them.

A

Littoral Zone
Limnetic Zone
Euphotic Zone
Profundal Zone
Benthic Zone

(BIOL 4503 Notes)

28
Q

Littoral Zone

A

The nearshore portion of a body of freshwater where photosynthesis can take place.

(Wikipedia)

29
Q

Limnetic Zone

A

The open and well-lit area of a body of freshwater excluding the littoral zone.

(Wikipedia)

30
Q

Euphotic Zone

A

The uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis.

(Wikipedia)

31
Q

Profundal Zone

A

The portion of a body of freshwater located below where light can reach.

(Wikipedia)

32
Q

Benthic Zone

A

The bottom of a body of water, including the surface and shallow subsurface layers of sediment.

(BIOL 2600 Notes)

33
Q

Riparian Zone

A

The transition zone between water and land along water bodies.

Includes everything from the low water mark to the uplands where vegetation may be influenced by elevated water tables or flooding and by the ability of the soils to hold water.

(Naiman & Décamps, 1997)

34
Q

What are some benefits the riparian zone provides?

A

Vegetation strengthens bank limiting erosion.

Vegetation also traps sediment from runoff and during floods as well as pollutants.

Wood debris creates habitat, traps sediment, and provides protection for small animals.

Forests impact microclimate.

Provides allochthonous nutrients/food.

Impacts transfer of N and P in water.

Acts as migration corridor.

(Naiman & Décamps, 1997)

35
Q

What are the biggest ways humans are impacting riparian zones?

A

Flow variability & channel width.
Invasive species.

(Naiman & Décamps, 1997)

36
Q

Watershed

A

Area of land in which all water drains downslope into a body of water such as a river, lake, reservoir, wetland, estuary, or ocean.

Also known as drainage basin or catchment.

(Zale et al, 2012)

37
Q

What are the flow patterns within a river?

A

Highest velocity is in the centre of the river near the surface.

Lowest velocity is along the shoreline and the river bottom.

In bows, it is fast outside and slow inside.

(BIOL 4503 Notes)

38
Q

Flow Refugia

How are they used by freshwater biota?

A

When flow hits obstacles.

Bugs use boundary layer (right at top of obstacle).

Fish use dead zones and eddies behind obstacles as ambush spots (lots of food falls in area).

(BIOL 4503 Notes)

39
Q

What is the big difference between the river continuum concept and the flood pulse concept?

A

River continuum concept describes longitudinal changes whereas flood pulse concept describes lateral changes.

40
Q

Flood Pulse Concept

A

Explains how the periodic inundation and drought (flood pulse) control the lateral exchange of water, nutrients and organisms between the main river channel (or lake) and the connected floodplain.

(BIOL 4503 Notes; Wikipedia)

41
Q

What ecosystem services do rivers provide?

A

They provide a fundamental one by providing a linking service connecting habitats which is needed by ecosystems to function e.g., nutrient transfer, migrations.

(BIOL 4503 Notes)

42
Q

Why is natural streamflow important?

A

Streamflow timing and quantity are critical components of water supply, water quality, and the ecological integrity of river systems.

Streamflow, which is strongly correlated with other characteristics of rivers such as water temperature, channel geomorphology, and habitat diversity, can be considered a master variable that limits the distribution and abundance of riverine species and regulates the ecological integrity of flowing water systems.

(Poff et al, 1997)

43
Q

What are the five components of the flow regime? Define each.

A

Magnitude of Discharge
(amount of water moving past a fixed point in a given time)

Frequency
(how often a flow above a given magnitude recurs over some specified time interval)

Duration
(period of time associated with a specific flow condition)

Timing or Predictability
(the regularity at which flows of defined magnitude occur)

Rate of change or Flashiness
(how quickly flow changes from one magnitude to another)

(Poff et al, 1997)

44
Q

What determines a river’s flow?

A

All river flow derives ultimately from precipitation, but in any given time and place a river’s flow is derived from some combination of surface water, soil water, and groundwater.

Climate, geology, topography, soils, and vegetation help to determine both the supply of water and the pathways by which precipitation reaches the channel.

(Poff et al, 1997)

45
Q

How does river flow relate to biodiversity?

A

In rivers, the physical structure of the environment and, thus, of the habitat, is largely defined by the movement of water and sediment within the channel and between the channel and floodplain.

Different habitat features are created and maintained by a wide range of flows and by the available sediment, woody debris, and other transportable materials that are moved and deposited by flow.

Over periods of years to decades, a single river can consistently provide temporary, seasonal, and persistent types of habitat that range from free-flowing, to standing, to no water which has promoted the evolution of species that use the different habitats in different ways and species that use it differently depending on their life cycle stage.

It has also resulted in species able to persist in the face of seemingly harsh conditions, such as floods and droughts, that regularly destroy and re-create habitat elements.

(Poff et al, 1997)

46
Q

What are the benefits and disadvantages of high flows?

A

B’s

Provides good nursery habitat.

Brings nutrients back into channel.

Leaves nutrients on floodplain after water recedes rejuvenating soils for new plant growth.

Transports sediment through channel including organics and algae giving nutrients to biological community and helping organisms with fast life cycles reestablish.

Brings woody debris into river creating new high quality habitat.

D’s

Flood displaces insects, fishes, and habitat.

(Poff et al, 1997)

47
Q

What are benefits and disadvantages of low flows?

A

B’s

Allows plants to colonize floodplain.

Has resulted in species with different behaviours tolerant of these conditions when they may not have been able to persist elsewhere because of other dominant species.

D’s

There is drought, water withdrawal, and habitat reductions.

It becomes harder for large fish to move upstream and reduction in pools may displace large fish downstream. There is also a higher vulnerability to avian predators.

(BIOL 4503 Notes; Poff et al, 1997)

48
Q

Why are the timing of flow events important?

A

The life cycles of many aquatic and riparian species are timed to either avoid or exploit flows of variable magnitudes e.g., spawning, migration, feeding.

(Poff et al, 1997)

49
Q

What are the geomorphic and ecological functions provided by different levels of flow?

A

Water tables that sustain riparian vegetation and that delineate in-channel baseflow habitat are maintained by groundwater inflow and flood recharge.

Floods of varying size and timing are needed to maintain a diversity of riparian plant species and aquatic habitat.

Small floods occur frequently and transport fine sediments, maintaining high benthic productivity and creating spawning habitat for fishes.

Intermediate-size floods inundate low-lying floodplains and deposit entrained sediment, allowing for the establishment of pioneer species. These floods also import accumulated organic material into the channel and help to maintain the characteristic form of the active stream channel.

Larger floods that recur on the order of decades inundate the aggraded floodplain terraces, where later successional species establish.

Rare, large floods can uproot mature riparian trees and deposit them in the channel, creating high-quality habitat for many aquatic species.

(Poff et al, 1997)

50
Q

What are some examples of ecological responses to alterations of the natural flow regime?

A

Depends on what was changed.

Loss of sensitive species
Stranding
Life cycle disruption
Invasive species
Reduced nutrients
Disrupt cues for fish
Altered plant cover types

(Poff et al, 1997)