“Exploring experimentally the impact of climate change and plastic pollution on the dynamics of bonamiosis in the native European oyster Ostrea edulis (7033)”

Exploring experimentally the impact of climate change and plastic pollution on the dynamics of bonamiosis in the native European oyster Ostrea edulis

The flat oyster, Ostrea edulis, is native from Europe. Overfishing and diseases have contributed to the decline of both farmed and wild populations of this species since the 19th century. The protozoan parasite Bonamia ostreae is the etiological agent of bonamiosis and is considered as one of the main threats for the ongoing flat oyster restoration programmes occurring in different European countries. However, the 21st century also faces climate change and ever-increasing plastic pollution, which might affect the dynamics of diseases such as bonamiosis.

The vulnerability of Ostrea edulis and of its associated communities including parasites to plastic pollution in the context of climate change was investigated experimentally in the frame of the MicroCO2sm project. A 9-months mesocosm experiment simulating actual and end-of-century environmental scenarios (ocean warming, acidification and plastics) was carried out in the Oceanolab structure (Oceanopolis center for scientific and technical culture). The project aimed at assessing changes in oyster life-history traits and ecosystem structure. As flat oysters originated from a Bonamia ostreae endemic zone, the dynamics of the parasite was investigated by quantifying the parasite by Real-Time PCR in oysters at the beginning and end of the experiments as well as in dead oysters collected throughout the experiment. In addition, the presence of the parasite was tested monthly in water and sediment in order to evaluate the amount of parasites released from oysters.

Results show that regardless of the tested conditions, Bonamia ostreae can infect, develop in oysters and be released in water. While mortality associated with the parasite appeared higher in conditions involving warming and acidification, the presence of plastics seemed to favor new infections. This experimental study enabled exploring for the first time the impact of climate and pollution changes on the dynamics of bonamiosis and allowed raising hypotheses that would deserve being further investigated to support the protection and ecological restoration of Ostrea edulis.

1. ARZUL, ISABELLE, IFREMER, Presenter
2. LECADET, CYRIELLE, IFREMER, Author
3. CHOLLET, BRUNO, IFREMER, Author
4. POUSSE, EMILIEN, OCEANOPOLIS, Author
5. CASTREC, JUSTINE, IUEM, Author
6. HUVET, ARNAUD, IFREMER, Author
7. PAUL-PONT, IKA, IUEM, Author
8. DI POI, CAROLE, IFREMER, Author