Marine conservation: Ecological Restoration

Restoration of the endemic oyster species - Ostrea edulis

The European oyster is considered a keystone species with special ecological function in its typical species community/habitat. Due to its global and regional significance it was recorded in the OSPAR list of threatened species and those deserving protection. Oyster beds are characterized as hot spots of biological diversity: they offer food, protection, substrate for fish and invertebrates and also act as a nursery habitat for many fish species. Overall, oyster beds provide valuable ecosystem services such as increased biodiversity, food and shelter for many species, improved water quality through filtration performance, locally reduced toxic algal blooms, and consolidated loose of sediments, coastal protection and in sum, an increase in the value of the surrounding ecosystem (ecosystem value).

European oyster stocks are classified as highly endangered throughout Europe. Permanent massive fishing pressure over centuries resulted in a collapse of oyster populations in the course of the 20th century in Europe. In German marine areas there is evidence that originally large oyster stocks have been devastated by overfishing. Those European oyster beds, which still exist today, are few and scattered: e.g. in Great Britain, Ireland and Denmark.

Feasibility studies and restoration experiments in the UK have shown that rehabilitation measures with oyster beds are based on long term concepts, promising, and the reconstruction of oyster beds is possible.

Interesting facts about the oyster

Scientific name:  Ostrea edulis
Common name: European oyster (German name: Europäische Auster)
Size: 12 to 20 centimeters
Age at sexual maturity: 3-4 years
Distribution area: Atlantic Ocean from Norwegen to Portugal and the Mediterranean. In Germany and Belgium the species is considered extinct
Habitat:            low water line to a depth of 40 meters
Biology: the free floating oyster larvae settle after a few days to a few weeks.  Once they settle and become established on appropriate hard substrates (preferential oyster and mussel shells), they remain as sessile organisms there
Diet: plankton organisms filtered from seawater