Diploma Thesis Candidate Andre Pechura (2007)
Attachment strength of Mytilus-byssus-threads on different surfaces of spat collector ropes
Plague of mussel byssus atached on substrate filament
The blue mussel Mytilus edulis L. is an important species for the aquaculture industry in Europe. Due to stakeholder conflicts and a shortage in spat availability in nearshore areas the expansion of this production sector is limited. In offshore areas wind farms could offer good opportunities for growing mussels on longlines installed in between offshore wind turbines. However, the conditions off the coast in the open ocean are harsh.
This study aims to evaluate which material provides the best attachment to the byssal threads of M. edulis under various physical aspects. Therefore, different collector materials with settled mussels were deployed in three test locations in the German Bight. One test area is 17 nautical miles off the coast in the vicinity of the lighthouse “Roter Sand”, one test area is close to the Jade Bay in Wilhelmshaven and the third between the two islands of Helgoland.
The detachment force, which is needed to remove a single mussel from the collector material, was measured with a digital force gauge. Further, the nanostructure of the collector material was analyzed by using scanning electron microscopy. The attachment strength to different materials and at various locations was compared.
Current velocities of approx. 1,5m/s were measured and wind speed can reach more than 30m/s and induce waves over 10m in height. To withstand these conditions the blue mussel anchors with byssus threads. The maximum adhesive forces of the mussels for the different materials varied from 8,48N to 10,42N. Different reasons for the loss of attachment could be found. Either the plaque was dislodged from the material or the threads broke, which happened in more than 50% of the cases.
Supervisor:
Prof. Dr. Bela H. Buck (AWI)