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Endures drought and cold
To suvive above sea-level, bladder wrack must
endure heat,
cold and drought. During certain times when there is a high pressure
and the winds carry water from the coast, it is possible that bladder wrack
to lay on dry land many consecutive days. As a protection against temperature
variations and drought, bladder wrack secretes a mucus. Those plants that
live highest up on the beach can survive, even if they lose 70% of their
normal water content that they usually have when submerged.
Bladder wrack can endure being frozen and many degrees below
freezing point. Water in the cells is not allowed to freeze, otherwise they
became damaged. To combat this, the cells produce a substance that functions
as a sort of antifreeze fluid. These substances reduce the cell fluids freezing
point in much the same way as glycol is used in the cooling system of a
car during the winter. When sea water around the cell freezes, the salt
content in the unfrozen water increases. It is rather the increased saline
contents that causes more damage to the plants than ice and cold.
Home for many
In the Baltic, bladder wrack is the only alga
that can build dense populations in shallow water. Therefore, they have
an immense effect on Baltic fauna. No other environment in the Baltic has
such a variety of specie and numbers as amongst the banks of bladder wrack.
It is possible to find mussels, periwinkles, polychaetes, flatworms, gribbles,
shrimps and tubeworms
on bladder wrack. On a single plant it is possible to find several
hundred individuals of the same specie.
Thread-like algae takes over
Bladder wrack is uncommon or has completely dissappeared
from certain areas within the Baltic where it was quite common before. This
also includes it vertical distribution, where it is now seldom found at
depths where it existed earlier. It is believed that over
fertilization from farmland is the reason. Over fertilization can result
in population explosions amongst plankton and other particles in the water
and thereby causing diminishing light penetration.
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