Compatisome of upper and lower rock shores pools
Compatisome of upper and lower rock shores poolsComparisons of Upper and Lower Shore Rock Pools
In the following study, rock pools from the upper and lower shore of Bracelet
Bay, were examined and the organisms within noted. The contents of the two pools were compared. The abiotic variations of the pools were recorded and examined in an attempt to understand why the contents of the pools differed.
A greater abundance and variety of organisms was present in the lower shore rock pool, this was due to the lower rock pool being a more benign environment than that of the upper shore. This was related to the exposure time of the two pools. The rock pool of the upper shore was exposed for longer and therefore suffered greater from variation of abiotic factors, as a result, the organisms of the upper pool had to possess special adaptations to colonise the area. The lower rock pool generally contained different species
which could out compete the organisms of the upper pool when in a more benign environment.
The rock pools studied should both contain organisms specially adapted to live in the intertidal environment of the rock pools. The organisms need to be adapted to the microenvironment of the rock pool, as conditions are considerably different to those of a �normal� marine environment. The rock pools spend some of their time completely submerged by the sea and other times exposed to the air. When exposed the organisms of the rock pool are part of a much smaller body of water than normal. This smaller volume of exposed water is likely to be changed significantly, mostly as a result of heating by the sun (Brehaut, 1982).
Heating of exposed rock pools mean that the organisms within have to cope with considerable abiotic variations There are three major factors which fluctuate in rock pools: 1. Temperature- this changes as a small body of water changes temperature quickly. Temperature also changes due to flooding by waves of different temperatures; 2. Salinity- this increase due to evaporation and decreases if the pool is diluted by freshwater e.g. rain. Salinity also changes like temperature, through flooding by the sea. 3. Oxygen- this decreases with increased temperature and can also come in short supply if the pool is crowded (more of a problem at night when plant life respires as well), (Nybakken, 1988).
As well as the above, carbon dioxide and pH vary. Carbon dioxide increases usually as a by-product of respiration, leading to a decrease in pH. Hence the organisms found in the rock pool should be able to tolerate changes in O2, CO2, temperature, pH and salinity. Such organisms include Balanus, Actinia, Patella, and Littorina who are all able to reduce their metabolic rate when the rock pools are exposed and so conserve limited oxygen, (Brehaut, 1982). Because of the changing salinity, the organisms should also be able to maintain a suitable osmotic potential even if the pH is far from optimal. Such organisms include...
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