Chapter 4,5,6 Flashcards
abiotic factors
- current
- sediment
- temperature
- chemistry
what does current do?
- transports material
- removes waste
- downstream displacement
Reynold’s number
the ratio of inertial forces to viscous forces
Re = Fi/Fv inertia/viscosity
Froude number
gravitational forces/intertial forces
Fr<1 subcritical
Fr= 1 critical flow
Fr> 1 supercritical
inertia
resistance to change in motion
viscosity
resistance to change in form due to mutual attraction of water molecules
hydraulic jump
- entrains air, oxygenates stream
- launch pad for fish moving upstream
- makes sounds of water as air bubbles burst
- habitat for aquatic organisms
thermal heterogeity due to:
- ground water
- shading
- runoff
- wind
- evaporative cooling
sinuosity
channel distance/straight down valley distance
Bernoulli principle
as velocity increases, pressure decreases
bank full stage
channel forming flow
stream armoring
heavy sediment on top of finer
transport
bed load, suspended load, dissolved load
competence
largest partical that can be moved at a particular flow
critical velocity
velocity needed to pick up and transfer a particular grain size
shear stress
force of water above stream bed
subtrate
the key to determining the abundance and distribution of species
substrate assumptions
- simple habitats are less diverse than complex habitats
2. intermediate disturbance leads to greater diversity
species abundance correlated with:
- amount of detritus
- algal biomass
- substrate stability and complexity
- depth
- velocity
intermediate disturbance hypothesis
low amount of disturbance= a few dominant species will take over,
high disturbance= loss of species
