Biotic and abiotic factors influencing attachment strength of blue mussels Mytilus edulis in suspended culture

Abstract

Mussels secrete byssal threads regularly to the substratum, and the strength of these threads can fluctuate with time. The present study examined weekly variations in the attachment strength of 2 yr old cultured mussels Mytilus edulis on submerged longlines in a semi-enclosed lagoon from late May to mid-October. Some possible factors influencing attachment strength were investigated: environmental factors (temperature, food availability, wind velocity and hydrodynamic conditions such as current velocity, turbulence and wave height) and reproductive condition were measured concurrently. Attachment strength was measured directly on cultured mussels using a dynamometer. Attachment strength varied 2-fold from summer to fall, a difference related not only to the number of byssal threads but also to their individual strengths. The hierarchical influence of each factor on attachment strength is discussed. Our results suggest that spawning seemed to be corre- lated with an important decrease (-32%) in attachment strength, and that water temperature (nega- tive relationship) and turbulence (positive relationship) were the most important factors explaining the variation in mussel attachment strength. In contrast to previous studies carried out in intertidal zones, no trade-offs were observed between reproduction and attachment strength. © Inter-Research 2008.