Investigating ecosystems Flashcards
What are transects used for?
- Continuous + systematic sampling
- Look at changes in organisms as a result of changes along an environmental gradient e.g. zonation along a slope
What is a continuous transect?
The whole line or belt is sampled
What is an interrupted transect?
Quadrats placed at intervals along the belt
Marine ecosystems // measuring salinity
Measure
- electrical conductivity of water
- density of water
Marine ecosystems // measuring pH
Seawater usually has pH of above 7
Can be measured using pH metre
Marine ecosystems // measuring temp.
- Temp. affects metabolic rate of organisms as many are ectothermic
- Lower temps. = lower metabolic rates
- Use thermometer
Marine ecosystems // what is the solubility of oxygen in water affected by?
TEMP
- higher temps. = lower concentrations of dissolved oxygen
WATER POLLUTION
- cause low oxygen concentrations
Marine ecosystems // measuring dissolved oxygen
oxygen-selective electrode connected to an electronic meter (give quick results, but need to be well maintained to give accurate results)
Marine ecosystems // wave action
areas with high wave activity = high concentrations of dissolved oxygen
e.g. coral reefs
What is turbidity?
The cloudiness of a body of fresh water
High turbidity = cloudy water
Low turbidity = clear water
Freshwater ecosystems // measuring turbidity
Turbidity limits penetration of sunlight + therefore the depth at which photosynthesis can occur
Measured using Secchi disc // a black + white disc attached to a graduating rope, the disc is heavy to ensure rope goes vertically down
Freshwater ecosystems // measuring flow velocity
- Measure the time a floating object takes to travel a certain distance e.g. an orange
- Floating object should be partially submerged to reduce effect of wind
- Method gives surface flow velocity only
- Divide by 1.25 to give avg flow velocity
Freshwater ecosystems // measuring pH
measured using pH meter
Terrestrial ecosystems // measuring air temp.
data-logging temperature probe can be used to measure temp. continuously
Terrestrial ecosystems // measuring light intensity
use electronic metres
Terrestrial ecosystems // measuring wind speed
- a ventimeter is a calibrated tube over which the wind passes
- this reduces pressure in tube, making a pointer move
- inexpensive + easy to use
Terrestrial ecosystems // measuring rainfall
use rain gauge + check every 24 hours
Soil // measuring soil moisture
- place soil in crucible
- weigh it
- leave for 24 hours to dry + weigh sample, repeat until its mass becomes constant
Measuring plant biomass
- dry plant material at 70 degrees until it reaches constant weight
- repeat 3-5 times
- extrapolate result to total biomass of that species in ecosystem
What is the Lincoln Index formulae?
N = (n1 x n2) / m2
N = total pop. n1 = no. animals first marked + released n2 = no. animals captured in 2nd sample m2 = no. marked animals in 2nd sample
What is the Simpson diversity index formulae?
D = {N(N-1)} / {n(n-1)}
D = Simpson diversity index N = total no. of organisms of all species found n = no. individuals of a particular species
What does a high value for D in Simpson diversity index indicate?
High value = highly diverse ecosystem + often stable, ancient site
