10. RCC Flashcards
What is the RCC?
River continuum concept
Who was the first person to think of the river as part of a system?
Noel hynes the stream and it’s valley
What does the valley determine?
Rock types, slope, biological community
What is TOC?
Total organic carbon
What are autographs?
Primary producers
What are secondary producers?
Heterotrophs
What are the functional feeding groups?
Shredders, collectors, scrapers, predators
What is a river pool?
Area before blockage
What is a river riffle?
Area after pool flow
What is a river glide?
Area after riffle, flat water
How large is a reach system?
10’1m
Why is it important to view the river from different spatial scales?
So we get a better understanding about the scale and structure of the river
What is riparian vegetation?
Plants that grow on the edges of the stream
What is woody debris?
More than 1m long 10cm in width
What does DOC stand for?
Dissolved organic carbon
What does POC stand for?
Particulate organic carbon
What is CPOM?
Coarse particulate organic material, more than 1mm
What feeding group feeds off CPOM?
Shredders
What is FPOM?
Fine particulate organic matter, less than 1mm
What feeding groups eats FPOM?
Collectors
Give examples of primary producers?
Moss, phytoplankton, other autotrophs
What is the first stage of river leaf decay?
Leaching, 25%mass lost in 24 hours
What is organic carbon that originated outside the stream called?
All allochthonous carbon
Where is a common place for diatoms to grow?
Surface stones
Who developed the river continuum concept?
Vannote et al 1980, introduced in 1980 to explain adjustments in biological communities
What is organic carbon that comes from the stream called?
Autochthonous carbon, eg diatoms
What are the common terrestrial elements found within rivers?
Ca, Mg, K, Na, Si, Cl
Why are rivers important for the global nutrient cycle?
Take nutrients to the oceans
What is Hemimetabolous?
Incomplete metamorphosis leads the insect to develop in a series of instars, normally 6-12
What is Homonetabolous?
Insect has a complete metamorphosis, in to a larvae this pupae then turns into a fully grown adult
Who developed the functional feeding group idea?
Cummins 1974
What are shredders?
Use CPOM, normally leaves from riparian zones, eg stone fly, create FPOM in the process
What are collectors?
Gatherers which collect organic matter from the bed of the river eg chironomidae
What are collectors?
Filterers, filter FPOM from the water column eg simuliidae
What are collector filterers?
Mix of the two, eg caddisfly, can spin nets to trap pray
What are scrapers?
Scrape attached algae from the surface of stones, normally flat to reduce drag
What elements are limiting to productivity?
C,P,N
What is the name of the process that a nutrient atom goes through on the way down rivers?
Nutrient cycling
What are river predators?
Eat the other kinds of invertebrate, invertebrates or small fish
What is the second stage of leaf decay?
Conditioning, colonised by fungi using n and p, lasts about 30 days
What is the third stage of river leaf decay?
Invertebrate shredding?now tasty leaves are rated by invertebrates, 20% loss, CPOM to FPOM
What is the 4th stage of leave decay?
Physical abrasion, CPOM to FPOM
What do some leaves use to stop breakdown?
Chemicals that deter insects
Who created stream order?
Strahler
What are the most common feeders at the upland reaches of the river?
Collectors 50% and shredders around 40%
What feeders are common at the middle reaches of the river?
Grazer and collectors about 45% each
What fish inhabit the upper reaches of the rcc?
Trout grayling
What are the main feeding groups at the lowland reaches of the RCC?
Collectors and predators
Which is the only feeding group to be found all throughout the RCC?
Collectors
Why are there few scrapers in the headwaters?
Low light penetration causes low periphyton
What stream order is a head water stream?
1-3
What is longitudinal displacement termed as in the river?
Nutrient spiralling
How long is an atom traveled downstream in an inorganic form?
90%
Why are organic forms relitievly stationary?
Because plants and invertebrates don’t move much
Why are large steams dominated by collectors?
Little light on the bed
Name a place where river see little detritus?
Nz lack of river trees
What natural process and interrupt rivers?
Beaver dams
What is the argument for fictional feedin groups?
Aren’t insects always generalists
How much co2 is dissolved within rivers?
80%
How much carbon is stored in small rivers?
<1g c/m
What impact visually can dissolved carbon have?
Change in river colour
How is DOC uptaken?
By organic layers on stones or Aufwuchs
What forms the layout of the aufwuchs?
Bacteria, enzymes, fungal hypha, cyano bacteria
What is DIC?
Dissolved inorganic carbon
How is detritus trapped in a aufwuch?
By fungal hypha, colonised by yeast and bacteria
What is the equation for the nutrient cycle?
Spiral length S, =uptake length Sw + Turnover length So
What is uptake length?
Average distance travelled by a nutrient molecule in organic form before removal from the water column
What are the 2 factors influencing nutrient uptake?
Biochemical, the biota doing the uptake, bacteria fungus algae. Geomorphology, physical properties of the channel, dictates residence time
What does the retention of the system depend on?
Tightness of the spirals
What does fluvial Geomorphology retention depend on?
Hydrology, size of particle. Heterogeneity of the stream bed, LWD
Where are aural rates short?
Where nutrients are high in demand
What are hypotheic zones?
Important areas of nutrient processing. Strong gradients in oxygen status create redox gradients, water moves slowly through bed sediments
What did people think before Noel hynes paper?
The stream was devoid of the valley and its surroundings
What determines ion availability in rivers?
Rock types, can control buffering
What is the name for the river hierarchical scale?
Mesosystems
How large normally is the riparian margin?
20-30 meters
What are the two types of collector?
Gatherer and filterers
