Test 2.1 River Continuum Concept (RCC) and Nutrient Spiralling Flashcards
What are the hierarchal scales in rivers and what are their sizes?
Stream system 10^3m Segment system 10^2m Reach system 10^1m ‘Poolriffle’ system 10^0m Microhabitat system 10^-1m
Definition of Riparian vegetation
Vegetation that grows alongside the edge of the stream. Typically up to 30m to the side
Formula for total organic carbon
Particular organic carbon + dissolved organic carbon (<0.7μm)
Definition or particular organic carbon
Coarse particular organic carbon (CPOM >1mm) + fine particular organic matter (FPOM <1mm)
What makes a system an autotrophic system?
When photosynthesis / respiration >1
What makes a system a heterotrophic system?
When photosynthesis / respiration < 1
Definition of Allochthonous carbon
Organic carbon originating from outside the stream e.g. leaves
Definition of Autochthonous carbon
Organic carbon originating from inside the stream e.g. diatoms, periphyton algae
Definition of Instars
Different growth stages when the insect sheds its exoskeleton and grows a new one - can be up to 12 instal stages
What are Hemimetabolous insects?
Insects with nymphs that resemble the adult
What are Holometabolous insects?
Insects where larvae and pupae do not resemble adult e.g. caddisflies
What do the shredders functional feeding group eat?
They eat coarse particular organic matter (CPOM). Particularly leaves from the riparian zone. This creates fine particular organic matter.
What do the collectors functional feeding group eat?
Collector gatherers: carbon (FPOM) from the bed of the stream
Collector filterers: Filter FPOM from the water column. e.g. black flies, caddisfly larvae- build nets to filter FPOM
What do the Scrapers functional feeding group eat?
Scrape attached algae from the surface of stones and rocks- some mayfly nymphs
What do the Predators functional feeding group eat?
Eat the other 3 types of invertebrates and sometimes small fish e.g. stonefly nymphs
Name the 4 types of invertebrates feeding groups
Shredders
Collectors
Scrapers
Predators
Describe the decay stages of leaves that fall into streams
- Leaching- 15% to 25% in the first 24 hours – leachate up taken by bacteria
- Conditioning- colonization initially by fungi using N & P and then bacteria colonize. About 7% loss during this phase and takes 30 days
- Invertebrate shredding- accelerates breakdown by 20% - CPOM to FPOM
- Physical abrasion – CPOM to FPOM
What are the most attractive leaves to shredders in order? Why?
Elm>Alder>Oak>Beach>Maple
Elm attracts fungi and bacteria a lot more than maple. Shredders prefer leaves with fungi and bacteria on.
What is a first order stream?
A stream that flows from a source e.g. groundwater, lake, glacier
What is a second order stream?
A stream following the meeting of two first order streams
What is a third order stream?
A stream following the meeting of two second order streams meet
Amazon and Mississippi can go up to 12th order stream
Describe the invertebrate breakdown of headwater streams
Order 1-3 <6m width
Dominated by shredders and collectors
Few scrapers as photosynthetic algae is low due to low light
Typically heterotrophic
P/R >1
Describe the invertebrate breakdown of middle reaches streams
Order 4-6, 6-75 width
Large amount of scrapers due to increase photosynthetic algae and light
Collectors the same as headwater streams
P/R >1
Describe the invertebrate breakdown of large rivers
Orders 7-12, width 75-700m
Dominated by collectors- gathering and filtering organic material from upstream reaches
Scrapers not present as light does not reach bottom
P/R <1
What are the criticisms of the River Continuum Concept (RCC)
- Developed for pristine systems
- Some headwater streams have low tree lines e.g. NZ
- Natural interruptions by lakes and ponds e.g. beaver ponds
- Fictional feeding groups? Can invertebrates be placed into groups or are they generalists?
What proportion of carbon is dissolved in rivers?
Up to 80% between 1-15g/m^3
In small forested catchments <1g C/m^3
How do organic layers and biofilm affect primary productivity?
Makes it more constant throughout the year. Less of a dip in winter
What are the limiting factors of productivity?
C, P, N. Therefore go through extensive utilisation as it passes downstream
What is nutrient spiralling?
Nutrient atoms undergoing transformations within a cycle to return to a previous state. This occurs over some distance downstream.
The closer the spirals the more efficient the system.
What proportion of the distance nutrients travel downstream is in organic form?
Inorganic - 90%
Organic - 10%
What is the formula for spiral length?
Spiral length (S) = Uptake length (Sw) + Turnover length (So)
Uptake length= average distance travelled by a nutrient molecule in inorganic form before removal from water column
–> Measure of nutrient retention efficiency
What factors affect nutrient uptake?
Biochemical: the biota e.g. Bacteria, fungi, algae, macrophytes
Geomorphic: the physical properties of channel e.g. Dictates residence time of water within reach
How does demand and flow affect spiral length?
High demand means short spiral length
High flow means longer spiral length
What are the 4 dimensions of river systems?
Lateral
Longitudinal
Vertical
Temporal
What is the River Continuum Complex?
A model to explain the adjustments in a biological community as a response to a continuum of integrating physical gradients along a river.
Natural rainwater pH
5.64 pH
Lake or river pH
4.5 pH
Equation for carbon dioxide dissolving in water to produce carbonic acid
CO2 + H20 H2CO3 (carbonic acid)
Carbonic acid dissociation equation
H2CO3 HCO^3- + H^+ CO^3– + 2H+
