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Compare the abioitc characteristics of aquatic and terrestrial environments:

Aquatic environment: Is an underwater environment

Terrestrial environment: A land environment

Abiotic characteristics Aquatic environments Terrestrial environments

Viscosity (the stickiness

of a fluid and its power to

resist movement)

Water is more viscous than air

Water provides more resistance and it

is therefore more difficult for an

organism to move through it than air

Organisms with more streamlined

shapes find it easier to move through

water

Air is less viscous that water

Air provides less resistance and it is

therefore easier for an organism to

move through than water

A human finds it easier to walk

through air than to walk through

water because the high viscosity of

water provides greater resistance

against any movement.

Buoyancy (the ability of

an object to float in a

medium)

Water provides much more buoyancy

and support than air. Water may not

only hold an organism up but may

also maintain its shape e.g. jellyfish

Air provides a very small amount of

buoyancy and support. Land

organisms therefore need more

supporting skeletal and muscular

structures to assist with support

Temperature Only small temperature changes occur

in aquatic environments.

Temperature changes in water are

more gradual

Large variations in temperature can

occur in terrestrial environments overshort periods of time. Daily

temperatures may vary up to 20c in

one typical day.

Pressure As the depth of water increases,

pressure increases.

Deep-sea organisms must be adapted

to the crushing effects from the

pressure of the water above them.

Only small variations occur in

pressure on land. Organisms in

environments at sea level are under

more pressure than those in

environments on high mountains

above sea level.

Small daily fluctuations in pressure

may occur due to weather changes.

Light availability When the sun is high in the sky more

light can be absorbed, whereas at

sunlight the light strikes the water

surface at more acute and less light is

absorbed.

Cloud cover will affect the intensity

and the length of time the light strikes

Light availability is abundant on land.

Cloud cover may reduce a small

proportion of light availability.

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the water.

The cloudiness (turbidity) of the

water affects the light availability.

This depends on the disturbance or

movement in the body of water thatmay disturb the soil, organic material

or other small particles or objects in

the water.

Gasses (O2 and CO2) Where air and water are in close

contact, gases from the air (O2 and

CO2), readily dissolve in water. The

more movement in water the more

gases dissolve.

Temperature also affects the amount

of gases in water. As temperature

increases, dissolved gases decrease.

Oxygen can carbon dioxide are found

in abundant quantities for terrestrial

organisms.