Biocide triclosan damages byssal apparatus in Mytilus galloprovincialis

In this study we describe the effects of a common environmental contaminant, the Triclosan1, on the byssal apparatus of the marine mussel Mytilus galloprovincialis. The aim in particular was to understand if this biocide, largely used in personal care products, impairs byssal threads formation, structure and/or anchoring efficiency. To this end, the mussels were exposed for 7 days to 10 mg/L triclosan2,3 and the effects were monitored by a multidisciplinary approach. The effects on byssal glands cytoanatomy were studied by light and electron microscopy while the biochemical effects were investigated in situ by PAS staining and in protein extracts. Functional impairment of byssal glands was assessed by determining changes in thread growth rate and resistance to traction after cut off;3 the organization of regrown byssal treads was also verified in histological sections. Experimental evidences indicate that marked alterations are induced by the biocide, primarily in collagen polymerization. This interference causes a significant loss in threads resistance and also a delay in regrowth. Such alterations would cause a consistent loss in the ecological fitness of mussels in nature since they typically live in areas exposed to tidal and waves action, protecting the coastline from erosion. Triclosan release in coastal environments therefore should be more carefully monitored so to prevent unwanted drastic consequences.