Aquascope Facts
Cliff and rocky beach ecology

The green filter

Cod in green waters
The cod swims up towards the light from the green dusky deep.

Of greater importance than pressure is the sea´s light filtering effect. Light penetrates light about 2000 times better than through water, even if the water is clean and particle free. The waters around Sweden contains colouring agents and particles that originate from land and quite often many single celled algae. Because of these, 80% of the light can be filtered away already at a depth of 2 m and the green light penetrates the deepest because the red and blue light are filtered the most.
    The strength and wavelength of the light also effect which algae will be present and therefore red algae usually increase in numbers with depth. They can even grow when there is only a weak light source. Cliffs at depth are rarely bare, where algae cannot grow, the surface is usually covered with attached creatures.
   In Swedish waters, salinity usually increases and is more stable at depth. This is probably one of the reasons why certain specie that are common in shallow waters along other coasts are common deeper down in Swedish waters.

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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