Living on a rocky foreshore

The foreshore, a difficult environment

The rocky foreshores are environments composed of hard and not very friable rocks, which are uncovered when the tide is low and submerged when it is high. The sand present on this area is brought by the currents during the tides. These conditions are difficult for organisms that must find ways to survive.

The hollows and nooks of the rocks provide organisms with many places to hide and protect themselves. It is not uncommon to find in these nooks and crannies spawning eggs or sometimes even a lobster. The flat parts are areas where organisms can attach themselves firmly. The algae are fixed in particular thanks to a spike.

Adaptations of organizations

This type of environment being difficult, the great majority of the species present had to adapt to these conditions in order to live. To resist the drying out during low tide, some organisms produce mucus to maintain the necessary level of humidity. Others, like limpets need a fairly regular rock to be able to attach themselves so that there is no space between the rock and their shell. If its shell is not perfectly adapted to the shape of the rock where it is, it will lose its water supply and dry out. At high tide, limpets move around and graze on algae and then return to the exact same spot on their rock and in the same position at low tide.

Importance of brown algae for life on the foreshore

Brown algae provide food and habitat for the many species that live there. Bladderwrack and knotted Ascophyllum, for example, are the basis of the diet of many gastropods such as the Yellow Littorine.

When the seaweed dies or when it is torn off during storms, it is transported by the currents on the coasts and all around its place of origin. By decomposing, the seaweed will put back into service organic matter that can be assimilated by all the surrounding ecosystems.

Finally, brown algae retain sea water like real sponges and thus help maintain a high level of humidity at low tide. It is this humidity that allows marine species to continue to live when the tide is low without suffering from the lack of water.