Effects of bioactive extracellular compounds and paralytic shellfish toxins produced by Alexandrium minutum on growth and behaviour of juvenile great scallops Pecten maximus

•Alexandrium sp. can produce PST and other bioactive extracellular compounds (BEC) with allelopathic and cytotoxic activity.•BEC cause tissue alteration, thus altering recognition and feeding processes of P. maximus.•PST reduce the efficiency of scallop P. maximus escape response and cause muscular damages.