lec 8

Question 1

by what metrics are streams/rivers expressed?

Answer 1

volume/time (ex. m^3/s)

Question 2

what is the availability of ions like in winter vs summer? what about DOC?

Answer 2

ions accumulate in winter while DOC accumulates in summer (since rivers are usually frozen, DOC cannot accumulate in winter)

Question 3

where is a river the fastest?

Answer 3

when movement is just between water

• at the shore, it is slowed by the wetted perimeter
• drag at the air-water interface (boundary layer)

Question 4

what are the dynamics of a riffle vs a pool?

Answer 4

riffles are little bumps in a river bed while pools are dips (idk theres a pic on lec 8 slide 4)

at riffles, velocity is highest when water is low-flowing
at pools, velocity is highest when water is high-flowing (water builds up at the riffle)

Question 5

how does stream order work?

Answer 5

order increases by (n+1) where two (n) streams meet (streams must be of the same order)

Question 6

what is the order for low order creeks? what are their primary characteristics?

Answer 6

order is 1-3
- shallow
- low discharge
- typically shaded by canopies –> lots of organic input (high DOM/DOC)
- primarily decomposition based food web (heterotrophic)

Question 7

what is the order for medium order creeks? what are their primary characteristics?

Answer 7

order is 3-7
- moderately deep
- moderate flow
- not shaded –> lots of access to light
- primarily photosynth based food web (autotrophic)

Question 8

what is the order for high order creeks? what are their primary characteristics?

Answer 8

order is 8+
- deep
- fast
- turbid –> little access to light
- primarily heterotroph based food web

Question 9

what is the difference between allochthonous and autochthonous inputs? which order streams experience which?

Answer 9

allochthonous: organic input that comes from external sources (ex. leaves falling into a river)

autochthonous: organic input produced in house

low order are allochthonous while med order are autochthonous

Question 10

match characteristic to order:
- COPM
- FOPM
- benthic algae
- benthic invertebrate
- phytoplankton
- zooplankton

Answer 10

COPM: low
FOPM: high
benthic algae: low
benthic invertebrate: low
phytoplankton: high
zooplankton: high

Question 11

where does maximum primary production occur in rivers?

Answer 11

medium order rivers (4-7)

Question 12

how does lake order compare to river continuum concept?

Answer 12

similar in concept, where lakes feed into one another, mostly based on location in geography

lower order lakes are higher in ion concentration since they pool as u move down