This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The European flat oyster (Ostrea edulis) was once widespread but has now become so scarce in the North Sea that it no longer forms ecologically functioning reefs. Along with the demise of the flat oyster, the three-dimensional structures that provide habitat for more than 100 marine species have disappeared.
Restoration therefore focuses not only on the return of the European flat oyster itself but also on the reef and its associated biodiversity. In a growing number of European countries, local oyster restoration relies on cultured oysters or wild oysters from foreign areas to supplement existing populations or establish new ones. Dutch restoration projects use oysters from Ireland and Norway, among others, as well as Dutch oysters cultured in hatcheries.
Sophie Valk, a Ph.D. candidate at Wageningen University & Research, investigated the genetic consequences of such practices, which are still rarely considered when determining restoration strategies. Her thesis is titled "Prying Genomes : Providing a molecular foundation for sustainable oyster restoration." Genetic diversity is important for the ability of populations to adapt to factors such as rising seawater temperatures and pathogens. Oysters may also be genetically adapted to the conditions in their native area of origin.
Oysters from elsewhere may therefore be less likely to survive or thrive in Dutch conditions. Another risk is that traits beneficial to the local population may gradually become less common when foreign oysters are used to supplement remnant wild Dutch populations. Valk therefore mapped the genetic variation of the European flat oyster.
According to her, a tailored genetic approach means examining which wild oysters are already present in each restoration area, how genetically diverse that population is and where the oysters used for restoration originate. Their relatedness and genetic differences from the local population must also be considered. "We have reached the next stage in European flat oyster restoration: scaling up," says Valk.
"It is crucial that we use our extensive genetic knowledge of the species when developing restoration strategies. This will allow us to prevent the inadvertent loss of genetic diversity and thus make oyster reef restoration more efficient and sustainable." Valk compared the remaining wild Dutch populations with oysters from Ireland and Norway and with hatchery-cultured offspring of wild Dutch oysters. The wild Dutch populations proved to be genetically diverse and formed a single group with extensive exchange of genetic material.
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