River Continuum Concept

Summary

The River Continuum Concept, introduced by Van Note in 1980, describes the changes in a river system from headwaters to large river systems. It discusses the transition from small streams to larger rivers, emphasizing the importance of stream order and the role of the riparian canopy in determining channel width and light penetration. The concept also explores the shift in organic matter from coarse particulate matter in headwaters to fine particulate matter in larger streams, influenced by aquatic macroinvertebrate communities. The script delves into the distribution of shredders, grazers, collectors, and predators within these communities, and how temperature affects the habitat preferences of different fish species, such as trout, smallmouth bass, perch, and catfish.

Takeaways

• 🌊 The River Continuum Concept (RCC), introduced by Van Note at all in 1980, describes the changes in a river system from headwaters to a large river system.
• 🏞️ A 'lotic system' is a comprehensive term for a flowing body of water, which includes rivers, streams, and creeks, and avoids size-based distinctions.
• 🔍 The concept of 'continuum' in RCC refers to the differences in elements of a sequence, such as the transition from headwaters to larger river sections.
• 🌿 The canopy plays a significant role in RCC by influencing channel width and the amount of sunlight that reaches the stream, affecting primary production.
• 🔄 Stream ordering is a method to categorize streams based on their size and connectivity, with first-order streams being the smallest and each increase in order representing a merging with a similar-sized stream.
• 📊 Van Note's original diagram from 1980 illustrates the relationship between stream order and channel width, showing an increase in width with higher stream orders.
• 🍃 In headwater streams, coarse particulate organic matter (CPOM) is prevalent, which is broken down by shredders, a type of aquatic macroinvertebrate.
• 🌱 As streams progress to mid-reaches, the shift from CPOM to fine particulate organic matter (FPOM) occurs due to the action of aquatic macroinvertebrates, particularly grazers.
• 🐟 Different fish species inhabit different reaches of the river based on their temperature and oxygen requirements, with trout favoring cold, oxygen-rich headwaters.
• 📉 The proportion of predators in the aquatic ecosystem remains relatively constant across different reaches due to the limited energy available at the top of the trophic pyramid.

Q & A

What is the River Continuum Concept?

The River Continuum Concept, developed by Vannote et al. in 1980, is a model that describes the physical, chemical, and biological changes that occur along the course of a river system from its headwaters to its mouth as it transforms into a large river system.

What is the difference between a 'river' and a 'lotic system'?

A 'river' is a general term for any flowing body of water, while a 'lotic system' is a more comprehensive term that includes streams, rivers, and creeks, emphasizing the continuous flow of water without necessarily defining the size.

What does the term 'continuum' refer to in the context of the River Continuum Concept?

In the River Continuum Concept, 'continuum' refers to the concept that describes how elements of a continuous sequence or series, such as a river system, differ from one another along the river's course.

How is stream order determined?

Stream order is determined by the branching pattern of the stream network. First-order streams are the smallest tributaries. When two streams of the same order join, the resulting stream is one order higher. For example, two first-order streams form a second-order stream, and two second-order streams form a third-order stream.

What is the significance of channel width in relation to the River Continuum Concept?

Channel width is significant because it influences the amount of sunlight that penetrates the water, which in turn affects the type of organic matter processing and the aquatic macroinvertebrate communities present. Narrow channels in headwaters can be covered by the canopy, while wider channels in larger rivers allow less canopy cover.

How does the canopy cover affect the stream ecosystem?

The canopy cover affects the stream ecosystem by regulating the amount of sunlight that reaches the water surface, which influences primary production, temperature, and the type of organic matter processed in the stream.

What is the difference between coarse particulate organic matter (CPOM) and fine particulate organic matter (FPOM)?

Coarse particulate organic matter (CPOM) consists of larger organic particles like sticks and leaves that fall into the stream. Fine particulate organic matter (FPOM) is smaller and more broken down, typically resulting from the processing of CPOM by aquatic organisms.

Why do shredders dominate in headwater streams?

Shredders dominate in headwater streams because these areas receive a high input of coarse particulate organic matter (CPOM) from the surrounding terrestrial ecosystem, and shredders are well-adapted to break down this larger organic material.

How do grazers differ from shredders in the context of the River Continuum Concept?

Grazers, unlike shredders, primarily feed on fine particulate organic matter (FPOM) and algae that grow on substrates in the mid-reaches of the river where sunlight can penetrate and support algal growth.

Why do collectors become more prevalent in larger river systems?

Collectors become more prevalent in larger river systems because these areas have slower water flow, which allows for the deposition of fine sediments. This creates an environment where collectors, which feed on suspended particles and detritus, can thrive.

How does temperature influence the distribution of fish species in a river?

Temperature drives the distribution of fish species within a stream because different species have specific temperature requirements for their metabolic processes, growth, and reproduction. Trout prefer colder water, while species like catfish and perch can tolerate warmer conditions.

Outlines

00:00

🌊 Introduction to River Continuum Concept

The video begins with an introduction to the River Continuum Concept, developed by Vannote et al. in 1980. This concept describes the changes in a flowing body of water from its headwaters to a large river system. The video explains the terminology used to describe these water bodies, emphasizing the use of 'lotic system' or 'stream' over 'river' to avoid size-related misconceptions. The concept of 'continuum' is introduced to describe the differences in elements along a continuous sequence, such as the varying characteristics of a stream from its headwaters to its mouth. Stream ordering is then discussed as a method to categorize streams based on their size and the number of tributaries they have, starting with first-order streams and increasing as more streams of the same order join.

05:02

🌿 Aquatic Ecosystems and Energy Sources

This segment delves into the energy sources that drive aquatic ecosystems, highlighting the shift from coarse particulate organic matter (CPOM) in headwaters to fine particulate organic matter (FPOM) in larger streams. The video explains the role of sunlight as the primary energy source and how it influences the type of organic matter present. The discussion then moves to the role of aquatic macroinvertebrates, particularly insects, in breaking down organic matter. Shredders, which are prevalent in headwaters, tear apart CPOM, while collectors filter out smaller particles. The video also covers the transition from shredders to grazers as one moves from headwaters to mid-reaches, where sunlight allows for algae growth on substrates. Lastly, it touches on the dominance of collectors and predators in large river systems due to the slowed flow and reduced availability of suitable habitats for shredders and grazers.

10:03

🐟 Distribution of Fish Species Along the River Continuum

The final paragraph discusses the distribution of fish species along the river continuum, influenced by factors such as water temperature and oxygen levels. Trout are found in the upper reaches where cold, well-oxygenated water is present, while smallmouth bass inhabit areas with cooler but not necessarily cold water. Perch and catfish are adapted to live in larger river portions with less oxygenated water. The video concludes with an assignment for the viewers, asking them to explore the role of the canopy in the river continuum, compare CPOM and FPOM, discuss the constancy of predator proportions, and explain how temperature affects fish distribution. The assignment is to be submitted via Moodle within a week.

Keywords

💡River Continuum Concept

The River Continuum Concept (RCC) is a model that describes the physical, chemical, and biological changes that occur along the length of a river system, from its headwaters to its mouth. It was developed by Van Note et al. in 1980. The concept suggests that rivers are not uniform and that their characteristics change predictably from source to mouth. In the script, the RCC is used to explain how different segments of a river support different types of organisms and processes, such as the shift from coarse to fine particulate organic matter as one moves downstream.

💡Lotic System

A lotic system refers to a flowing body of water, such as a river or stream. The term is used to emphasize the dynamic nature of these water bodies, which are constantly in motion. In the video, the lotic system is contrasted with the term 'river' to highlight that the latter is often used more colloquially and does not necessarily convey the size or characteristics of the water body. The script discusses how lotic systems change in size and character as they progress from headwaters to larger river systems.

💡Stream Ordering

Stream ordering is a method used to classify streams based on their size and the order in which they join together. In the script, first-order streams are the smallest, and as two streams of the same order join, they form a stream of the next higher order. This system helps to understand the hierarchy and connectivity within a river network. The script uses stream ordering to illustrate how the size and characteristics of streams change as they converge to form larger rivers.

💡Canopy

The canopy in the context of the video refers to the tree cover above a stream or river. It plays a crucial role in determining the amount of sunlight that reaches the water surface, which in turn affects the growth of algae and the overall energy dynamics of the ecosystem. The script explains how the canopy's influence on channel width and light penetration can vary along the river continuum, impacting the types of organisms that can thrive in different sections of the river.

💡Coarse Particulate Organic Matter (CPOM)

Coarse particulate organic matter (CPOM) consists of larger organic particles, such as sticks and leaves, that fall into streams and rivers. These materials are important because they provide food and habitat for various aquatic organisms. In the video, CPOM is discussed in the context of headwater streams where it is abundant and supports a community of shredders, insects that break down these large organic materials.

💡Fine Particulate Organic Matter (FPOM)

Fine particulate organic matter (FPOM) refers to smaller, more broken-down organic particles found in streams and rivers. As CPOM is processed by shredders and collectors, it becomes finer and can be utilized by different organisms. The script explains the shift from CPOM to FPOM as one moves downstream, indicating changes in the types of organisms that can process these materials.

💡Shredders

Shredders are a group of aquatic macroinvertebrates, often insects, that feed on coarse particulate organic matter by breaking it down into smaller pieces. They play a vital role in the decomposition process and are typically found in the headwaters where CPOM is abundant. The script describes how shredders are a significant component of the insect community in these areas and how their presence changes along the river continuum.

💡Collectors

Collectors are aquatic macroinvertebrates that feed on fine particulate organic matter suspended in the water column. They are filter feeders and play a significant role in processing organic matter in streams and rivers. The script explains that collectors become more dominant in larger river systems where the water flow is slower, allowing for the accumulation of fine organic particles.

💡Grazers

Grazers are aquatic macroinvertebrates that feed on algae and other microorganisms that grow on submerged surfaces. They are typically found in areas where sunlight can penetrate the water, allowing for algal growth. The script discusses how grazers replace shredders in mid-reach areas of the river where the canopy is less dense, and sunlight can support algal communities.

💡Predators

Predators in the context of the video are aquatic macroinvertebrates that feed on other invertebrates. They are present in all sections of the river but their proportion relative to other organisms remains relatively constant. The script explains that predators are at the top of the food chain and their numbers are limited by the amount of energy available to them, as depicted by the trophic pyramid.

💡Temperature

Temperature is a critical factor influencing the distribution of fish species within a river system. Different species have different temperature preferences, which determine where they can survive within the river continuum. The script discusses how trout prefer cold, oxygen-rich headwaters, while species like catfish and perch are found in larger, slower sections of the river where temperatures are warmer.

Highlights

The River Continuum Concept describes the changes in a river system from headwaters to a large river.

A lentic system is a more comprehensive term for flowing bodies of water than 'river'.

The concept of a continuum helps to understand the differences between various parts of a river system.

Stream ordering is a method to categorize streams by size and connectivity.

First-order streams are the smallest and increase in order as streams merge.

Stream size increases with the order number, affecting channel width and ecosystem characteristics.

Canopy coverage plays a significant role in determining stream width and energy input from sunlight.

Organic matter in streams shifts from coarse particulate matter in headwaters to finer particles in larger streams.

Aquatic macroinvertebrates like shredders, collectors, and grazers are influenced by stream order and characteristics.

Shredders are prevalent in headwaters, breaking down coarse organic matter.

Collectors become more dominant in mid-reaches as organic matter becomes finer.

Grazers replace shredders in mid-reaches, feeding on algae growing on substrates.

In large river systems, collectors and predators dominate due to slower flow and substrate coverage.

The proportion of predators remains consistent across different stream orders due to energy availability.

Fish distribution in streams is driven by temperature and oxygen requirements.

Trout prefer cold, oxygenated water in the upper reaches of streams.

Smallmouth bass inhabit areas with cool but not necessarily cold, oxygenated water.

Perch and catfish are found in larger river portions with less oxygenated water.

Assignment instructions are provided to analyze the River Continuum Concept's impact on stream organisms.

Transcripts

hello and welcome to today's discussion

of the river continuum concept the river

continuing concept was written by van

note at all in 1980

the river continuing concept attempts to

describe how a stream or river or

flowing body of water

changes from headwaters until it becomes

a large river system

so i thought first we should probably

define what these terms mean

a river is any flowing body of water

oftentimes we refer to them as a

lodic system and in fact loading system

is much more

provides a lot more depth than the term

river because river equals stream equals

creek it was branch fork there's many

different terms we can use to describe

flowing bodies of water but oftentimes

we start trying to think well

a creek is probably smaller than a river

and a branch is smaller than a creek so

on and so forth

the best term is lodic system or stream

both of these mean

flowing bodies of water they don't

really give a lot of definition of

size we're going to get into that just

to a moment here

what is a continuum then well the

continuum is the concept which attempts

to describe how

elements of a continuous sequence or

series

differ from one another so that's a big

long definition

saying well how would the headwaters

differ from the mid-reaches

from the large river portions of this

lodic system

another way of thinking of it is a

spectral and you're comparing

the ends and middles of different

portions along that spectrum

so let's kind of get into this idea in

this concept

of what a flowing body of water and what

these systems

are and how a large stream compares to a

small stream

a way to do this is something called

stream ordering

and what i've got here is i've got a

stream network and this stream network

flows

in this direction and you can tell that

because it has small stream

portions these headwaters that are

branched and flowing

into the large main stem what we're

going to do is we're going to go through

and label each one of these with the

corresponding

stream order if you remember a couple

lectures ago

we went over this in class so i'm just

going to briefly go through and do this

without providing a tremendous amount of

explanation

however we will go into this later on so

first off we're going to label all the

first order streams so these are all

first order streams

now what we can do is we can go through

and label the second order streams

if you remember it takes two of the same

magnitude streams in order to change

stream order so since we have a first

order stream joining another first order

stream

at this point we would consider that to

be a second order string

same goes for right here same goes for

right here

right here and right here

since a second order stream meets a

first order stream

it remains a second order stream at that

point

remember you have to have equaling

magnitude in order

for the streams to change so i'm going

to go ahead and go label

where all of that happens and i think

those are the only two

what we now has is we now have a second

order stream meaning another second

order stream

so at this point we now have a third

order stream

and we also have a third order stream

here

since a third order stream meets a

second order stream at this point

it remains a third order stream at that

point

however at this point we have a third

order stream

meeting another third order stream that

means we have

a fourth order stream at this point

so you can see as the numbers of the

stream order get larger

so we expect the stream to get larger

that's an important concept because it

starts giving us an idea of the

magnitude of streams

and that is what we're going to find in

this image

the image i'm sharing with you here is

from

vanote at all 1980 and you can see that

round down here this is one of the

original diagrams

published in this in his publication

if we look at this like a graph on the

y-axis we can see in stream size or

order just like we came from so we have

first second third

all the way to 12. then along the x-axis

we'll see relative

channel width so if we take a look at

first order streams we expect them to be

very narrow

and a 12th order stream we expect to be

very wide

since a first second third and sometimes

even fourth

but generally first second third order

streams

we're just focused on those the stream

channel width

is small enough that the canopy can

cover

ninety percent or more of the channel

but once you get beyond the third or

fourth

ordered streams the channel width

becomes so wide that the canopy can

it couldn't cover everything that plays

a major role because remember

sunlight provides 99.9 percent of energy

to all ecosystems on the planet this

happens to be an ecosystem in which sun

provides a hundred percent of energy

the energy comes from this material

falling

into the stream called a loctimus

material

a loctinous material are things like

sticks and leaves

and any sort of organic matter falling

into the stream

if you notice there's another term here

called coarse

particulate matter you will also see

that labeled and

talked about as coarse particulate

organic matter

or c pump c palm

shifts from the in the headwaters c

palmer coarse particulate matter

and then when we get into the mid

reaches and further down

we get into something called an f pump

which is

not particulate organic matter and we

can see that

down into these reaches why does it

break down why does it shift from coarse

to fine

the reason it makes this shift is due to

the aquatic macroinvertebrate

communities

remember aquatic macroinvertebrates or

anything that live in the water

that's larger that you can see with a

naked eye

and they're an invertebrate a lot of

these are insects but not all of them

are we're going to focus on the insects

for just a moment though

in the upper reaches we find a large

proportion of the insect community known

as shredders

if we take a look at this diagram this

diagram makes up a pie

chart imagine all of this meaning a

hundred percent of the insect or back or

aquatic macroinvertebrate community in

this area

the shredders make up a large proportion

of it and what does a shredder do

a shredder will tear these of course

particular organic matter

pieces apart things like leaves sticks

stuff like that are falling in

they'll shred them apart they're not

actually eating the leaves or sticks

they're eating the fungi and

bacterial communities that have

inhabited

these areas and starting to eat it

themselves so they're terrible and

they're in

all these little bacteria and fungi

communities and stuff

next we have the collectors and

collectors are just an organism

that filters things out of the water so

i see shredders are tearing it up the

collectors then

are getting the pieces that the

shredders are breaking down

so we see collectors starting to play a

major role as we move down

let's now take a look at the mid-reaches

so we can see that shredders

have been replaced by grazers and in

fact the mid-reaches and upper reachers

you can sort of flip-flop

the small proportion of grazers turns

into shredders and this large

portion of shredders turned into grazers

as we move

from the upper reaches or the headwaters

to the mid-reaches respectively

so grazers or any insect that will graze

and what are you grazing upon in a

stream

generally algae growing on a substa or

substrate

you have to have sunlight for that algae

to grow

so when the canopy opens up enough in

these areas

it allows the sunlight to penetrate the

rocks and everything like that

penetrate the water and hit the rocks so

that algae can grow

on the rocks but the water is still

shallow enough in these areas that it's

the sunlight can reach the bottom when

we start getting into the deeper

breeches of the stream

that's where we start running into some

problems with light striking the bottom

and there's a couple other things we'll

get into in just a moment but right

through here is where we see the grazers

playing a major role because again

the sunlight can penetrate and hit those

rocks

and create that nice little substrate

for those algae communities to grow on

so the grazers like snails and some

caddisflies and various things

will then eat off of that substrate

when we get into the large river system

you've noticed we've lost the shredders

and grazers and we now only have

collectors and predators

the reason we have a large proportion of

collectors is the stream has slowed down

significantly

in these large river portions when a

stream slows down

all of the substrate or excuse me all

the substances being carried by the

river

falls out and covers the substrate so we

would expect not to have very many

shallows portions through here and if we

did those shallow portions are probably

going to be a mud or fine silted bottom

versus a nice clean rocky bottom up

through here so you're not going to get

the algae communities that the grazers

need

and you're not going to be narrow enough

to have a lot of sea palm coming in the

river that your shredders need

so we're going to be dominated by

collectors throughout this entire region

now what you will note is that predators

tend to stay the same

and why do predators stay the same

predators make up the same proportion in

the upper

mid and lower reaches the reason is is

due to this concept here that we

discussed a while back

this you may notice a trophic pyramid

and if you look the trophic pyramid at

the very top we see top predators and

then the next below is intermediate

predators

predators make up a very small

proportion of

the amount of energy available in an

ecosystem

when we take a look back at this image

we can see that there's some predators

here

here and here but it's the same

proportion the reason is is these

insects and micro invertebrates they

don't care if they're eating collectors

or grazers or shredders it doesn't

matter to them

they're just still eating whatever's

available but you can only have so many

predators because that's as much

energy as available remember only ten

percent of the energy transfers

from one level to the next and you can

see that denoted

very clearly here with the energy 1000

to 100 to 10

to 1. so we would expect to find

fewer predators

than shredders collectors or grazers

but the concept of the proportion of

predators

shouldn't change as we move through this

area

next we're going to talk a little bit

about the fishes over here remember

the term fishes is correct when you have

multiple types of

fish so we have trout smallmouth bass

perch and catfish

trout usually inhabit the upper reaches

of the stream they need very cold and

highly oxygenated water

the upper reaches of the streamers

generally have a higher gradient which

means they're steeper

which allows water to fall and when it

makes these waterfalls and riffles and

such it's aerating it and putting

atmospheric oxygen into the water

smallmouth bass are sort of what we'll

call a tweener they're in between the

top and the middle

they usually require cool oxygenated

water but not necessarily cold

and then finally perch can survive in

these sort of the upper portions of the

mid reaches they don't mind

or excuse me the lower portions of mid

range is the upper portion of the large

river reaches

they don't have to have as much

oxygenated water and in fact

cold water can put a an actual impact on

them

the same goes for catfishes catfishes

like to live in the larger river

portions

because they live on the bottom and

they're going to be searching around

for a lot of dead decaying matter and

various other organisms that's going to

fall

out so temperature is really what's

driving the differences

in these fish communities here

so that's a kind of a quick little

explanation of how the river continuum

concept

impacts how organisms are distributed

in a stream what i'm going to do now is

talk a little bit about your assignment

remember this will be posted up

to moodle for you to do so i'm going to

show it to you here first though

and and you can see the instructions

just respond to the following questions

each one of these is worth five points

so i want you to kind of give the same

amount of feedback per

question so it's a 35 point assignment

first off what role the canopy play in a

river continuum concept remember there

we're talking about channel width and

canopy

so how does canopy cover relate to

channel width that's sort of what we

were just talking about

how you compare and contrast course

particular organic matter and find

particulate organic

matter next why does the proportion of

predators not change just discuss

that why do lower reachers have no

shredders and grazers

why do you see upper and middle reaches

with a large proportion of collectors

and then finally how does temperature

drive uh the

distribution of fishes within a stream

all this can be explained

but this image and this talk i'd like to

have this due within a week

and if you could just upload your

assignment to moodle and we'll go from

there

thanks guys