Response of an invasive aquatic crustacean to the fish toxicant rotenone.

Lepak JM, Pate WM, Cadmus P, Hansen AG, Gallaher KD, Silver DB. 2024. Response of an invasive aquatic crustacean to the fish toxicant rotenone. Lake Reserv Manage. 40:317–324 Fisheries managers have used the piscicide rotenone for invasive fish control and other management objectives for decades, yet the effects of rotenone on some aquatic species are not well understood. We tested the effects of rotenone on an invasive crustacean Mysis diluviana that can have deleterious effects on aquatic food webs (e.g., zooplankton communities) and ultimately some native and sport fishes. The median 50% lethal concentration (LC50) was assessed for M. diluviana at 24, 48, 96, and 192 h using active rotenone concentrations from 0 to 4111 ppb. At 24 and 48 h, LC50s were not reached, and at 96 and 192 h, LC50s were estimated at 4853 (95% CI = 1280–8426) and 668 (385–952) ppb, respectively, above (∼25-fold and 3-fold) recommended rotenone application concentrations to control fishes. Our results suggest that rotenone concentrations and exposure times used for controlling invasive fishes are likely to have limited to no effect on invasive M. diluviana populations. Thus, if M. diluviana control is a management objective, rotenone applications targeting invasive fishes are unlikely to contribute to this objective, and other methods should be considered that take advantage of potential vulnerabilities of M. diluviana, like temperature and light sensitivity. [ABSTRACT FROM AUTHOR]