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What is eutrofication?
| Compared to the rocks in the background of the
picture above, a great many more one-year green algae grow on the
rocks in the foreground. One reason for this is that more nutrients
reach those stones that are closest to the stream in this part of
the bay. There are no human pollutants in the stream, but it runs
through a bank
of seaweed. The black coating on the rocks is not oil, but black
cyanobacteria. The rocks further up are bright and bare because
they are situated in the unfriendly bare
belt. |
The supply of nutrients to the sea is a
prerequisite for Marine life and is therefore not an environmental problem.
A problem arises when variations in the supply of nutrients effect the character
or function of the ecosystem negatively. By nutrients, we mean elements
that organisms (i.e. alga) need to photosynthesise and develope normally.
The most important of these nutrients are nitrogen and phosphorous that
are normally taken up in the form
of ions : nitrogen as nitrates, nitrites or ammonium; and phosphorous
as phosphates.
When we refer to eutrofication of the sea, we often
mean environmental pollution, but eutrofication really means "to enrich
with nutrients". An ecosystem can be eutrophic without being damaged
or negatively effected, it can be nutritous and luxuriant. Commonly, eutrofication
is wrongly thought to mean över-fertilization, that the system recieves
too many nutrients and results in the occurrence of a great many fast growing
algae and that certain micro-organisms thrive in greater numbers.
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