River and Riparia Ecology Flashcards
In general, what is the River Continuum Concept?
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)
How are the components of the River Continuum Concept grouped?
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)
Allochthonous
Nutrients come from outside the water.
(BIOL 4503 notes)
Autochthonous
Nutrients come from within the water (primary productivity).
(BIOL 4503 Notes)
What is a river?
A body of water with unidirectional flow, that is sloped, and has a defined channel.
(BIOL 4503 Notes)
How does stream order work?
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)
What are the basic components of a river?
Headwaters
Tributaries
Mouth
Channel
Slope
Stream Order
Floodplain
(BIOL 4503 Notes)
Floodplain
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)
Channel
Where the bulk of water flows through in a river.
(BIOL 4503 Notes)
Headwaters
Where river originates i.e., 1st order stream.
(BIOL 4503 Notes; ENSC 3106 Notes)
Tributary
A river or stream flowing into a larger river or lake.
(Mac Dictionary)
Describe how the source of nutrients changes within a river based on the River Continuum Concept.
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)
Describe how the dominance of invertebrates within a river changes based on the River Continuum Concept.
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)
What are the functional feeding groups of invertebrates?
Shredders
Collectors
Scrapers (aka grazers)
Predators
Shredders
Invertebrates that eat coarse particulate organic matter such a leaf litter.
(Vannote et al, 1980)
Collectors
Invertebrates that filter their food from transport, or from sediments, which is fine and ultra-fine particulate organic matter.
(Vannote et al, 1980)
Scrapers aka Grazers
Invertebrates that eat algae from surfaces.
(Vannote et al, 1980)
Predators in the RCC
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/
Describe how fish composition within a river changes based on the River Continuum Concept.
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)
Aside from nutrients, describe how the other abiotic factors change along a river based on the River Continuum Concept.
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)
What are the zones of a body of freshwater? Draw them.
Littoral Zone
Limnetic Zone
Euphotic Zone
Profundal Zone
Benthic Zone
(BIOL 4503 Notes)
Riparian Zone
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)
