Aquascope Facts
Cliff and rocky beach ecology


If several organisms try to exploit the same resource although it is too small, a competitive situation arises. Competition can arise between several individuals of the same species, or between individuals of different specie.
    Periwinkles grazing on cliffs and rocks can for example start competing for food when they became too many and the food source cannot reproduce itself in a quick enough tempo to replace those that have been eaten. In such a situation they can stop growing, even lose weight and die. If two specie compete for the same food source, for example the common periwinkle and the rough periwinkle, competition can be a possible reason for why one species is more common than the other within a certain area. This might be the result of a more effective exploitation of food resources, or that one species prevents the other from fully utilizing the resources.
    Amongst cliffs and rocks, competition can easily arise because a great many creatures want to utilize the substrate to attach to or to look for food. Many types of algae also need to be attached so they are able to utlilize the sunlight.
Halichondria competing with red alga
In the left-hand picture, a bead crumb sponge is seen dominating the bottom. Only a few older red algae are able get any room. New organisms probably have difficulty establishing themselves in this area. In the right-hand picture, a fast growing thread-like algae is seen growing over furcellaria lumbricalis. The red algae runs the risk of getting too little light.

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Cliffs and rocks are fantastic!
Zoning and flecked occurrence
Animals that are attached
Modular construction
Variation and change
Variations in water level
Wave exposure
Both cliffs and rocks
Freshwater and saltwater
Geography, climate and history
Organisms life cycles
Organisms effect on each other
Energy and the flow of material

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson