Tide Pool Physical Factors
|
Shape |
A
large, shallow pool has a large surface area to
volume ratio or a lot of the pool is exposed
at the surface. A small, deep pool has a small
surface area to volume ratio. Shape and volume
become important when we consider the other
factors that contribute to stress in a tide pool. |
Temperature |
The
temperature of tide pools is affected by air
temperature and direct sunlight on the pool. Shallow
pools with large surface areas are likely to
be more affected by temperature. The major impact
of temperature changes on organisms is a change
in rates of photosynthesis and respiration. For
every 10 degrees centigrade,
photosynthesis increases by one and a half times
and respiration by two to three times. This causes
a build up of by-products, such as carbon dioxide
and oxygen, within the water. |
Oxygen |
Photosynthesis
in plants, especially algae, cause oxygen concentrations
to peak in the afternoon. At night, available
oxygen is depleted rapidly and animals migrate
to the surface. A pool with a large surface area
to volume ratio will allow more oxygen to diffuse
into the water from the air. |
Carbon
Dioxide and pH |
The
other result of photosynthesis during the day
is that carbon dioxide is taken up by the plants.
As the level of carbon dioxide drops, the pH
rises, making the water more alkaline. This change
is reversed at night when photosynthesis stops
but plants and animals continue to respire
- using up oxygen and releasing carbon dioxide.
High levels of dissolved carbon dioxide in the
water make the pool more acidic. |
Salinity |
The
sun and wind evaporate water from the surface
of pools. In isolated tide pools, this
causes an increase in salinity (salt-concentration).
Heavy rainfall can lower salinity rapidly, however
the less dense freshwater often forms a layer above
the salty water. The mixing is not always uniform
and animals and plants in the pool's depths may
remain unaffected. Some species are able to survive
a wide salinity range. |
