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These favoured algae recieve an abundance
of nutrients and light. Between 30% and 50% of the total shallow bottom
area along the coast of Bohuslän can be covered by these one year green
algae. Most algae is found in the bays of northern Bohuslän.
The shallow bays are an important link between the sea and
the land, for example as a feeding area for certain birds that even spend
part of their life on land. They are even important as feeding and breeding
areas for commercially important populations of cod
and varying specie of flatfish, i.e. plaice.
Variations in vegetation and its composition are of great
importance for the presence of fish and bottom-living creatures, but because
of increasing over-fertilization and the resulting increase in the distribution
of the finely threaded algae, composition of the specie within this ecosystem
has changed. It has been shown that the flatfish population has decreased,
because a third of their breeding areas are no longer suitable and this
has mainly effected young plaice. It is believed that even the coastal cod
population has been effected in the same way because their feeding areas
have decreased in numbers.
It is not just over-fertilization that has caused the death
of bottom-living organisms. There are certain bottom-living organisms that
can take advantage of the increase in nutrients, as long as there is a supply
of oxygen. Such specie that can increase in numbers under such circumstances
are eel
and the shore
crab.
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