Managing invasive Styela clava populations: inhibiting larval recruitment with medetomidine

Abstract

Abstract The toxicity of the synthetic catemine medetomidine to <12 h-old larval clubbed tunicate, Styela clava , was assessed in 2-h laboratory bioassays. Exposure to medetomidine resulted in increasing rates of larval immobility with increasing concentration. The 2-h EC50 was 3.8 mg/L medetomidine. Larval settlement was highest at a concentration of 0.1 mg/L medetomidine. At higher concentrations of medetomidine, metamorphosis was initiated but not all larvae settled. The ability of medetomidine to reduce S. clava larval mobility and interfere with settlement suggests that it has potential as a management tool for controlling subtidal invasive S. clava populations. Key words: tunicate, population control, Selektope TM , toxicity bioassays, settlement inhibition, metamorphosis, biofouling Globally, invasive ascidians are a growing problem, with continuing range expansion of numerous species of solitary and colonial ascidians (Lambert 2007). The Asian clubbed tunicate, Styela clava