Attachment properties of blue mussel (Mytilus edulis L.) byssus threads on culture-based artificial collector substrates

The attachment strength of blue mussels (Mytilus edulis) growing under exposed conditions on 10 different artificial substrates was measured while assessing microstructure of the applied substrate materials. Fleece-like microstructure attracted especially mussel larvae, however, most settled individuals lost attachment on this type of microstructure with increasing size during the time of experiment. Substrates with thick filaments and long and fixed appendices were less attractive to larvae but provided a better foothold for juvenile mussels as shown by the results of the dislodgement trials. In addition these appendices of substrates could interweave with the mussels, building up a resistant mussel/substrate conglomerate. Our results show that a mussel byssus apparatus can withstand harsh conditions, if suitable substrates are deployed. Depending on cultivation aims (seed or market sized mussels) and cultivation method (one or two step cultivation), different collector types for larval attraction, good foothold and interweaving abilities or collectors combining these properties should be developed and applied. The study suggests that substrates need to be very precisely tailored according to the major environmental conditions. Furthermore, the results imply that a “one size fits all substrate” may not be the most culture-effective approach, but, in the contrary, substrates need to be changed and modified according to the size of the mussel as they go through their different life cycle stages.