NORA was delighted to welcome 65 experts and interested participants to the online NORA Genetics Workshop on 25th February 2021. The workshop was chaired by Pierre Boudry of Ifremer and an overview of current and planned research on Ostrea edulis of relevance to native oyster restoration was presented by researchers from five European research groups.
Video recordings of the presentations can be accessed by clicking on the talk title below.
Sylvie Lapègue (Ifremer)
Evolutionary history, convergence and genetic parallelism in the European flat oyster.
Jakob Hemmer Hansen (DTU)
Population genomics and management of the European flat oyster in Norway, Sweden and Denmark
Paulino Mártinez (University of Santiago de Compostela)
Population genomics of the flat oyster: genetic markers and candidate genes for resistance to Bonamia ostreae
Tim Bean (Roslin Institute)
Bonamia ostreae challenge on juvenile flat oysters (Ostrea edulis) to investigate host genetic resistance.
Manu Gundappa (Roslin Institute)
Sequencing and assembly of the European flat oyster genome.
Each presentation was followed by questions and engaging discussion of the findings so far, the opportunities to collaborate and share data, and ideas for future research of relevance to native oyster restoration. Participants contributed to word clouds outlining 1) What way genetics can inform or support native oyster restoration efforts (Figure 1) and 2) What we still need to find out about native oyster genetics in order to further support restoration (Figure 2), highlighting the multifaceted and important role that genetics can play in ecological restoration of this rare species. Four key topics were evident from the talks and the discussion. With input from Tom van der Have (Bureau Waardenburg), we summarise these key points here:
1. Population subdivision
There is interest from an ecological restoration perspective in the genetic structure across Europe. Identifying subpopulations is critical to inform understanding of the extent to which this should be accounted for in sourcing oysters for in-water restoration. Several studies show that four different European flat oyster subpopulations can be recognized: North Sea, Atlantic/Keltic, Mediterranean and Black Sea. It has been suggested in publications that this subdivision is more than isolation by distance alone. This implies that source material for restoration should preferably be derived from populations as close as possible and in any case, from the subpopulation where the restoration site is located. Geneticists can help restoration ecologists and project managers by assigning oysters from or destined to restoration sites to the relevant or appropriate population.
2. Genetic variation
Questions relating to the genetic variability present in hatchery reared stock (in particular but not only) are key, as this is a preferred method of sourcing oysters for some projects due to biosecurity concerns (see our European Guidelines on Biosecurity in Native Oyster Restoration). Inbreeding may reduce the fitness of the restored population. Geneticists can help restoration practitioners by estimating the genetic variation (or effective population size) of the restored population and source material and give advice how to improve or prevent inbreeding in hatcheries or spatting ponds.
3. Evolution of Bonamia tolerance
Restoration projects would benefit greatly from a clearer understanding of the genetic basis of tolerance to Bonamia. For projects in Bonamia affected areas, there is interest in ensuring that stock that are introduced have tolerance and also that introduced stock to not dilute any existing naturally occurring tolerance in the population. For projects in Bonamia free areas, there is an interest in future proofing efforts, although without increasing the risk of the disease being introduced in the process.
The presentations made clear that Bonamia tolerance appears to have evolved independently in several subpopulations. Marker genes have been found in one subpopulation and applied to other populations. Geneticists can help restorers by analysing the restored population or source oysters for the presence of Bonamia-tolerance marker genes. Bonamia-tolerant and Bonamia-free spat may be developed.
4. Sharing genetic samples
Finally, during discussion the positive impact that an informal inventory of existing samples and analysis could play in moving forward with answering outstanding questions related to native oyster genetics was identified. The group voiced a consensus that such an effort would be mutually benefited and supported. The group will be exploring the best way to assimilate and share this data over the coming months.