Aquascope Facts

Why are shallow bays effected by over-fertilization

Roads in a crowded archipelago
To be able to explain why 68% of the bays along the coast of Bohuslän became choked-up, several factors need to be taken into consideration. As we have disussed earlier, different human activities result in a large nitrogen load. Because of this increased supply of nutritive elements, the short lived algae has through competition ousted other algae and we have a new ecosystem where new specie establish themselves, which in turn can result in that certain bottom-living organisms are eradicated. With this course of events, we get fewer bottom-living organisms that can utilize the increased supplies of nutrients and this can have an accelerating effect: increased supplies of nutritive elements and fewer organisms that consume them.
    Man can also cause problems by stopping or redirecting water currents. As the years have passed we have built roads between different islands in the archipelagoes, for example embankments that are often built and choke the natural flow and hinder the exchange of water. Stagnant water usually results in that no new oxygen is supplied to the system. Today we have learned that by placing large piping in the embankments in a certain way, embankments can be built without choking the flow of water.
    Even when building other constructions, such as piers and carparks, a large exchange of water can still occur, but careful planning is needed and measures taken so that the flow of water is not changed in an unfavourable manner.
   That the occurrance of finely threaded algae is higher in northern Bohuslän compared to the southern areas can also be due to a naturally lower water exchange. Archipelagoes also have a great many islands and narrow passages that also reduce the flow of water.
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A splendid outing ?
Problems and expectations
”It was better before"
Seawater and soluble salts
The sea moves
Coastal waters are close to us
What is eutrofication?
Sources of over-fertilization
How the open masses of water are effected
How shallow bays are effected
What can we do?
Alga harvest

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