Clearance rates of Mytilus edulis exposed to parasites and microplastic

<p>Fear is an integral part of predator-prey interactions with cascading effects on the structure and function of ecosystems. Fear of parasitism holds a similar ecological potential but our understanding of the underlying mechanisms in host-parasite interactions is limited by lack of empirical examples. Here, we experimentally test if blue mussels <em>Mytilus edulis </em>respond behaviourally to the mere presence of infective transmission stages of the trematode <em>Himasthla elongata</em> by ceasing filtration activity, thereby avoiding infection. Our results show that blue mussels reduced clearance rates by more than 30% in presence of parasites. The reduced filtration activity resulted in lower infection rates in experimental mussels. The identified parasite-specific avoidance behaviour can be expected to play a significant role in regulating the ecosystem engineering function of blue mussels in coastal habitats.</p>