Effects of the sea lice chemotherapeutant, emamectin benzoate, on metabolism and behaviour of the sea-pen Pennatula phosphorea.

Chemotherapeutants used to control infestations by sea lice can be released into the marine environment surrounding aquaculture farms. Among these therapeutic agents, emamectin benzoate is extensively utilized even though its impact on non-target taxa has not been thoroughly examined. In this context, we explored the effects of emamectin benzoate on a common Norwegian habitat-forming species: the phosphorescent sea-pen Pennatula phosphorea. Specifically, we examined P. phosphorea metabolic and responses before, during and after exposure to emamectin benzoate. Results indicate that an 8-day emamectin benzoate exposure (0.8 mg/L) did not induce P. phosphorea mortality or significant behavioural or metabolic modifications. However, we highlighted the presence and persistence of emamectin benzoate in exposed P. phosphorea tissue. These results indicate that emamectin benzoate is unlikely to adversely impact P. phosphorea populations in the environment. However, persistence of emamectin benzoate in tissue constitutes a potential for bioaccumulation with repeated treatments and should be examined in further studies.