Experimental test on the use of MS-222 for ostracod anaesthesia: concentration, immersion period and recovery time

Anaesthesia of animals may be useful for different purposes, particularly for veterinary reasons or in experimental research, for manipulation or treatment of immobilized but alive animals. Its use in crustaceans is not uncommon, but it has never been described for Ostracoda. We provide brief and preliminary guidelines on the use of the tricaine mesylate (MS-222) on the widespread freshwater ostracod Eucypris virens and we show that this compound is an effective anaesthetic used as a bath treatment at minimum concentrations of 500 mg L-1. This value is considerably higher than that recommended for other aquatic animals like fish. Recovery time, ranging from 5 to 15 minutes, is mostly determined by anaesthetic bath concentration, while bath duration influenced to a lesser extent. Anaesthesia induced with MS-222 can prove useful for minute manipulation of living ostracods e.g. for identification, marking or image capture under the microscope.