Microplastic leachates disrupt the chemotactic and chemokinetic behaviours of an ecosystem engineer (Mytilus edulis)

• Published in: Chemosphere (Oxford) 2022-11, Vol.306, p.135425-135425, Article 135425
• Main Authors: Uguen, Marine, Nicastro, Katy R., Zardi, Gerardo I., Gaudron, Sylvie M., Spilmont, Nicolas, Akoueson, Fleurine, Duflos, Guillaume, Seuront, Laurent
• Format: Article
• Language: English
• Subjects: Blue mussel; Chemical Sciences; Chemical stimulus; Chemodetection; Cues; Environmental Sciences; Intertidal species; Life Sciences; Plastics; Predators
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.135425

The massive contamination of the environment by plastics is an increasing global scientific and societal concern. Knowing whether and how these pollutants affect the behaviour of keystone species is essential to identify environmental risks effectively. Here, we focus on the effect of plastic leachates on the behavioural response of the common blue mussel Mytilus edulis, an ecosystem engineer responsible for the creation of biogenic structures that modify the environment and provide numerous ecosystem functions and services. Specifically, we assess the effect of virgin polypropylene beads on mussels’ chemotactic (i.e. a directional movement in response to a chemical stimulus) and chemokinetic (i.e. a non-directional change in movement properties such as speed, distance travelled or turning frequency in response to a chemical stimulus) responses to different chemical cues (i.e. conspecifics, injured conspecifics and a predator, the crab Hemigrapsus sanguineus). In the presence of predator cues, individual mussels reduced both their gross distance and speed, changes interpreted here as an avoidance behaviour. When exposed to polypropylene leachates, mussels moved less compared to control conditions, regardless of the cues tested. Additionally, in presence of crab cues with plastic leachates, mussels significantly changed the direction of movement suggesting a leachate-induced loss of their negative chemotaxis response. Taken together, our results indicate that the behavioural response of M. edulis is cue-specific and that its anti-predator behaviour as well as its mobility are impaired when exposed to microplastic leachates, potentially affecting the functioning of the ecosystem that the species supports. [Display omitted] •Mussels are sensitive to their chemical environment.•No behavioural changes in mussels were detected in the presence of conspecific cues and injured conspecifics.•Mussels adapt their behaviour to the detection of predator cues by a reduction of their speed and gross distance.•Mussels' behaviour is impaired by microplastic leachates through a reduction in their motility for all cues tested.•Mussel direction changed when exposed to crab cues with microplastic leachates compared to crab cues alone.