|Tolerance of the European flat oyster (Ostrea edulis) and the blue mussel (Mytilus edulis) to suspended sediment exposure|
Somers, P. (2019). Tolerance of the European flat oyster (Ostrea edulis) and the blue mussel (Mytilus edulis) to suspended sediment exposure. MSc Thesis. NIOZ Netherlands Royal Institute for Sea Research: Yerseke. 25 pp.
A laboratory experiment was conducted in order to investigate the tolerance of the European flat oyster (Ostrea edulis L.) and the blue mussel (Mytilus edulis L.) to suspended sediment. The 28-day experiment was performed using nine cylinder tubes filled with untreated Eastern Scheldt water. Every tube contained three iron mesh baskets to support 2 mussels and 2 oyster each (54 individuals per species in total). The baskets were placed at different depths (10 cm, 45 cm and 80 cm below the water level). Sediment, collected in a salt marsh by means of sediment traps, was sieved (1 mm) and dried before being added to 5 of the 9 tubes. The mean concentrations that were achieved in the sediment treatment ranged from 966.16 ± 1358.64 mg L-1 at 10 cm depth to 3881.15 ± 9316.62 mg L-1 (± SD) at 80 cm depth. The other 4 tubes were used as control treatment in which no extra sediment was added. In order to investigate the tolerances, multiple physiological parameters were measured (i.e. survival, respiration rate, condition index, and biodeposit production). There was no difference in mortality between treatment or depth for both O. edulis and M. edulis (p=>0.05). Both the respiration rate and condition index of O. edulis and M. edulis were also not affected by the exposure to suspended sediment. However, both species had an increased biodeposit production at the end of the experiment. These results suggest that both O. edulis as M. edulis have a high tolerance for the exposure to suspended sediment. However, the physiological effects might not be clear as a result of the high variability in exposure. Additionally, extra responses (e.g. gaping and filtration rate) could help to understand the mechanisms determining the physiological performance. Understanding these mechanisms will ultimately be necessary to be able to mitigate adverse effects in both oyster restoration as mussel cultivation.