|Effects of burial on ostrea edulis|
Oosterwal, S. (2019). Effects of burial on ostrea edulis. Thesis. NIOZ Netherlands Royal Institute for Sea Research: Yerseke. 32 pp.
Information on the burial of the Ostrea edulis in literature was scarce and the marine contractor Van Oord had started a project which involved starting an oyster reef at Borssele V windpark. This created the need for Van Oord to approach project partners. NIOZ was one of the approached parties to conduct research for this project, named Ecoscour. This project focussed on the effect of a single burial on a single oyster scenario. The research was conducted inside mesocosms with aerated seawater in it. Oysters were placed inside pots filled with seasand. All pots were labelled and randomized before the experiment. At the designated time the pot was removed and the oyster was checked. If the oyster was alive it was analysed to see effects of burial on its survival. Condition index was a measure to help indicate why there was survival or not. The pots were checked if there was anything which could be a hint to what could have happened. After analysis the results showed that the condition index had not dropped to a level which could be considered lethal for any of the analysed oysters. After 14 days all the pots showed black sand and a smell which indicated the presence of H2S. The amount of black sand increased with each time frame and the smell stayed for the rest of the experiment. These results point toward a death by asphyxiation. Asphyxiation mostly seemed to happen to fully buried oysters in a vertical position. Horizontally buried oysters had a less high death toll during the experiment. Oysters that were not fully buried in a vertical position had very high survival. Direct contact with the water seemed to prevent asphyxiation in the not fully buried oysters. In conclusion burial in sandy sediment causes death and the amount of death increases with time until all individuals are dead and the cause of death is asphyxiation.