Topic 2.2

Measuring Abiotic Factors

Abiotic Factors

– Temperature– Rainfall– Light

– pH– Salinity– Nutrients– Availability of water

Climatic Factors

Edaphic Factors (soil)

Measuring Abiotic Components

• There are 3 main types of ecosystem where you might need to measure abiotic components:1. Marine (sea, estuary, salt marsh, mangrove2. Freshwater (river, lake, wetland)3. Terrestrial

Bozeman Science – what are abiotic factors

1. Marine Ecosystems

2. Freshwater Ecosystems

3. Terrestrial Ecosystems

Distribution of Earth’s Water

Examples of Abiotic Components

• Terrestrial Ecosystem– Temperature– Light intensity– Wind speed– Soil particle size– Slope– Soil moisture

content– Drainage– Soil mineral

content

• Freshwater Ecosystem– Turbidity– pH– Flow– Temperature– Dissolved

oxygen

• Marine Ecosystem– Salinity– pH– Temperature– Dissolved

oxygen– Wave action

Measuring Abiotic Factors

• Light– Use a light meter– Use a standard and fixed height– Avoid shade– Take readings at the same time of day– Standardise the direction it points

Measuring Abiotic Factors

• Temperature– Use an electronic probe with a datalogger– Use a standard height above ground or a standard

depth

Measuring Abiotic Factors

• pH– Use an electronic probe with a datalogger– Use a standard depth– Make sure the probe is clean– Make sure it is calibrated properly

Measuring Abiotic Factors

• Soil Particle Size– Large (stone-sized) particles can be measured

individually– The volume of smaller particles can be measured

using a series of successively finer sieves– Even smaller particles can be separated by

sedimentation

Measuring Abiotic Factors

• Windspeed– Use a digital anemometer if possible– A homemade propeller could be made– Indirect measurements can be made using the

Beaufort scale

Measuring Abiotic Factors

• Slope– Use a clinometer

For a slope of x◦:Percentage slope = tan(x) x 100

Measuring Abiotic Factors

• Soil moisture content– Weigh soil sample before and after heating and

calculated the mass of water evaporated off– Repeated readings taken until there is no further

change

Measuring Abiotic Factors

• Water flow velocity– Time how long it takes a floating object to travel a

fixed distance, i.e. Pooh Sticks– Alternatively a probe with a propeller attachment

may be used

Measuring Abiotic Factors

• Mineral Content– Minerals are non-volatile– If you have an oven which heats a sample safely to

500 – 1000oC for a number of hours, the remaining mass will be the mineral content

Measuring Abiotic Factors

• Salinity– Salinity can be measured indirectly by measuring

electrical conductivity (using a conductivity probe with a datalogger)

– Conductivity is a measurement if the ion content of a sample of water (in parts per thousand, ppt, %o)

Measuring Abiotic Factors

• Dissolved oxygen content– Use a dissolved oxygen probe connected to a

datalogger

Measuring Abiotic Factors

• Wave action– Use a dynamometer – an instrument which

measures the force of waves

Measuring Abiotic Factors

• Turbidity– This is a measure of the cloudiness of a water

sample– It can be measured using a Secchi disc. The depth

to which it must be lowered into the water in order to just become invisible is measured

– Alternatively a turbidy meter can be used. This shines light through a sample and records its absorbance by the sample

List whether each of these methods is suitable for marine, freshwater or terrestrial ecosystems