Mortality in the rockpool shrimp Palaemon elegans following long-term exposure to low doses of the anti-parasitic drug teflubenzuron

Abstract

Anti-parasitic drugs used to control sea lice infestations in the salmonid aquaculture industry are a growing environmental concern due to their potential impacts on non-target crustacean species. This study examined the lethal effects of teflubenzuron, a common in-feed pharmaceutical drug used on Norwegian salmon farms, on a non-target species, rockpool shrimp Palaemon elegans, following an extended exposure period. The standard daily dose for treating salmon is 10 µg teflubenzuron g −1 fish. Adult shrimp were fed 1 of 6 low doses of teflubenzuron (0, 0.0025, 0.005, 0.05, 0.094, 0.188 and 1.88 µg g −1) twice a week for a period of 66 d. Cumulative mortality reached 15, 27, 82 and 100% amongst shrimp exposed to the highest treatment groups (0.05, 0.094, 0.188 and 1.88 µg g −1 , respectively). Cumulative mortality amongst shrimp exposed to the 2 lowest teflubenzuron doses and control feed was low (5%). Dose response curves based on measured concentrations within the shrimp were used to calculate a series of lethal threshold concentrations (LC x). The LC 5 , LC 50 and LC 90 concentrations of teflubenzuron causing low, median and high levels of mortality in rockpool shrimp were estimated to be 1.2, 18.4 and 150.6 ng g −1 , respectively. These concentrations are similar to those reported in wild crustacean species, including shrimp species in the vicinity of Norwegian fish farms, both during and after teflubenzuron medication, suggesting that exposure to low doses of this compound can pose a significant risk to wild shrimp populations.

Methylmercury, Trace Metals, Organotins and Their Effects on the Qatari Mangrove Shrimp, Palaemon khori

“…However, single types of contaminants adversely affected survival when applied at ten times the ambient concentrations. This is line with previous studies conducted on the pink shrimp Pandalus montagui, where researchers a reported a 10% increase in the mortality levels with higher pollutant dosage [75]. Note, however, the reduced survival of shrimp when mercury was one of the pollutants involved in the combination of contaminants.…”

Distribution and Persistence of Diflubenzuron and Teflubenzuron in the Marine Environment Around Salmonid Aquaculture Facilities

“…Several studies have shown that benzoylphenylurea insecticides are highly toxic to crustaceans that undergo moulting, including shrimp, and lobsters (Samuelsen et al, 2014;Bechmann et al, 2018;Samuelsen et al, 2020). There is, however, limited information currently available on the levels of these compounds present in the marine environment around Norwegian fish farms consequently, it is difficult to assess whether diflubenzuron and teflubenzuron pose a risk to marine biota in the wild as well as to human health.…”