Aquascope Facts
Little bladder wrack

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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Close to the water surface
Endures drought and cold
Home for many
Thread-like algae take over

Protect themselves with poison and mucus

Eggs and sperm at the top

Bladder wrack without bladders

Bladder wrack     More facts     Other names

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