Abiotic factors in a rocky shore

Question 1

Wave action

Answer 1

Abrasive force of the waves as they crash against rocks and organisms

Question 2

Advantages of wave action

Answer 2

Strong wave action churns up sediments that contain food and nutrients for scavengers and filter feeders
Strong wave action mixes oxygen into the water so that more organisms can be supported

Question 3

Disadvantages of wave action

Answer 3

Erosion of rocks over time

Abrasive action on organisms can tear them off the rocks

Question 4

Adaptations to deal with wave action

Answer 4

Sheltering in crevices in the rocks or living high up on shore
Having a flattened or steam lined shape, byssus threads or having a large foot
Seaweeds are cylindrical or spherical to reduce resistance to wave action

Question 5

What is the water temperature of rock pools

Answer 5

Rock pools have a very wide range of temperatures because it is isolated from the rest of the sea and is quickly heated up by the warm rocks, air and the sun

Question 6

Water temperature of rock pools at night

Answer 6

Quickly chilled as it loses heat to the rocks and air

Question 7

The affect this has on organisms living in rock pools

Answer 7

Organisms aren’t able to move out of the pool and must therefore be able to cope with a wide range of temperatures

Question 8

Salinity

Answer 8

The amount of salt in the water

Question 9

Compare the salinity of sea water to rock pools

Answer 9

The salinity in sea water doesn’t change however salt concentration in rock pool changes as water evaporates

Question 10

What happens if the salinity rises too high

Answer 10

Animals must abandon the pool or die. Pools near the top of the shore are dangerous places for marine animal life as they can be isolated from the sea for long periods of time

Question 11

PH in rock pools

Close relationship between…

Answer 11

Number of seaweeds in a rock pool and the pH of the water.

Question 12

What happens to the pH of the water during the day

Answer 12

Seaweeds photosynthesise and use up the carbon dioxide in the water. Dissolved carbon dioxide is carbonic acid. As the co2 is consumed it makes the water less acidic

Question 13

What happens to the pH of the water during the night

Answer 13

Photosynthesis does not occur. The levels of carbon dioxide in the water increase. This makes the water very acidic. Organisms that can’t tolerate a wide pH range aren’t able to live in rock pools.

Question 14

Dissolved O2

Why can organisms in rock pools be in danger overnight if the tide is low

Answer 14

There is no fresh water filling the pools, to replenish the oxygen and no photosynthesis occurring so there is no oxygen being added to the water

Question 15

Dissolved O2 and the organisms that live there

Answer 15

Any organisms living in rock pools high up on shore must be able to cope with a ice range of dissolved oxygen levels in the water, or be able to move from one rock pool to another

Question 16

Tidal action

Answer 16

Mainly due to the gravitational affect of the moon and the sun

Question 17

Centrifugal force

Answer 17

When something spins around a central point, centrifugal force pushes that object away from the centre. Because the earth is spinning, the water is pushed away from the surface of the earth

Question 18

When will you experience tides

Answer 18

You will experience two high tides and two low tides every 24 hours

Question 19

What happens when the sun, moon and earth are in a straight line with eachother

Answer 19

This causes extra high high tides and extra low low tides. These special tides are called spring tides- spring high tide and spring low tide

Question 20

When do spring tides occur

Answer 20

They occur one full day after a new moon or a full moon

Question 21

What is tolerance

Answer 21

The ability of organisms to cope with exposure to air, or being trapped in a rock pool high up on the shore