RESUMO
Bath treatment chemotherapeutants, used to control sea lice infestations in the salmonid aquaculture industry, are released directly into the marine environment around fish farms and pose a serious risk to non-target species, particularly crustaceans. Hydrogen peroxide (H2O2) is the most frequently used bath treatment chemotherapeutant on Norwegian fish farms, however, limited information is available on its toxicity to European lobsters (Homarus gammarus), a commercially important species at risk of exposure due to its distribution overlapping with salmon farm locations. The aim of this study was to investigate the lethal effects of H2O2 on pelagic (stage I-IV) larvae/post-larvae and its sub-lethal effects on the benthic stage V H. gammarus. To assess the lethal effects of H2O2, we carried out a series of 1 h toxicity tests and assessed mortality after a 24 h post-exposure period. Exposure to H2O2 was toxic to all pelagic larval stages tested, with estimated median lethal concentrations (LC50) of 177, 404, 665 and 737 mg/L for stage I, II, III and IV, respectively. These concentrations represent approximately 10, 23, 40 and 43%, of the recommended H2O2 concentrations used for delousing salmon on Norwegian fish farms, respectively. To assess the sub-lethal effects of H2O2 on H. gammarus, stage V juveniles were exposed to H2O2 at concentrations of 85, 170 and 510 mg/L for 1 h and shelter-seeking behaviour and mobility endpoints were assessed. Numerous behavioural parameters including distance travelled to shelter, time to locate shelter and the number of shelter inspections, were negatively affected in lobsters exposed to H2O2 when assessed immediately after the exposure period. However, no differences between control and exposed lobsters were detected after a 24 h post-exposure period. Our results demonstrate that short term exposures to H2O2 are lethal to pelagic H. gammarus life stages and can negatively affect the shelter seeking behaviour of benthic life stages, though these behavioural changes may be short-lived.
Assuntos
Peróxido de Hidrogênio/toxicidade , Nephropidae/fisiologia , Animais , Aquicultura/métodos , Comportamento Exploratório , Pesqueiros , Larva/efeitos dos fármacos , Dose Letal Mediana , Nephropidae/efeitos dos fármacos , Noruega , Salmão , Testes de ToxicidadeRESUMO
Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target crustaceans. Azamethiphos and deltamethrin are two bath treatment pesticides used on salmon farms in Norway, however, limited information is available on their impact on European lobster (Homarus gammarus) larvae in the Norwegian marine environment. Here, we firstly report the lethal (LC50) and effective (EC50) concentrations of azamethiphos and deltamethrin for stage I and stage II larvae, following 1-h exposures. Using a hydrodynamic model, we also modelled the dispersal of both compounds into the marine environment around selected Norwegian farms and mapped the potential impact zones (areas that experience LC50 and EC50 concentrations) around each farm. Our data shows that azamethiphos and deltamethrin are acutely toxic to both larval stages, with LC50 and EC50 values below the recommended treatment concentrations. We also show that the azamethiphos impact zones around farms were relatively small (mean area of 0.04-0.2 km2), however deltamethrin impact zones covered much larger areas (mean area of 21.1-39.0 km2). These findings suggest that deltamethrin poses a significant risk to European lobster in the Norwegian marine environment while the impact of azamethiphos may be less severe.
Assuntos
Copépodes , Doenças dos Peixes , Praguicidas , Ftirápteros , Animais , Aquicultura , Larva , Nephropidae , Nitrilas , Noruega , Organotiofosfatos , PiretrinasRESUMO
The benzoylurea chitin synthesis inhibitor teflubenzuron, widely used against sea lice in North Atlantic aquaculture, may pose an environmental threat to non-targeted crustaceans. In this experiment, laboratory acclimated pink shrimp (Pandalus montagui), a species found in fjords with Atlantic salmon farming, were exposed to dietary teflubenzuron for 46 days (control; low dose: 0.01 µg/g; high dose: 0.1 µg/g). The exposure doses represent 0.1% and 1% of a standard treatment dose for Atlantic salmon. Mortality and prevalence of deformities, pharmacokinetics, oxidative stress and transcriptomic and metabolomic profiling were used to assess the response to teflubenzuron exposure. Mortality in the high-dose group was 25% (five of 20 individuals). No control or low-dose group shrimps died. Phenotypic responses,i.e., leg deformities (0 control, 6 low, 8 high) and cloudy eyes (0 control, 3 low, 7 high), were observed in some surviving shrimps (control n = 15, low n = 17, high n = 15). Accumulated levels of teflubenzuron in shrimps from the high-dose group ranged from 4.7 to 369 ng/g wet weight. Transcriptomic profiling showed very few significantly altered genes in the exposed shrimps. Teflubenzuron-induced changes to the metabolome pointed to well-known effects of benzoylurea agents, with reduced levels of N-acetylglucosamine indicating an effect on chitin synthesis. The metabolomic profiling showed that teflubenzuron exposure was associated with reduced energy metabolism. Some metabolites pointed to increased necrosis and/or bacterial overgrowth in the teflubenzuron-exposed shrimps. In conclusion, this study shows that teflubenzuron causes phenotypic effects in P. montagui exposed to 0.1% of the treatment dose given to Atlantic salmon.
Assuntos
Benzamidas/toxicidade , Metaboloma/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Pandalidae/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Aminoácidos/análise , Animais , Benzamidas/farmacocinética , Quitina/biossíntese , Metabolismo dos Lipídeos/efeitos dos fármacos , Pandalidae/metabolismoRESUMO
Infestations with salmon lice, a parasitic copepod, is a major problem in the salmon farming industry. Teflubenzuron is an in-feed pharmaceutical applied to control lice outbreaks; the standard medication is 10â¯mg per kg fish per day for seven days. Surveys reveal that teflubenzuron accumulates and persists in the sediment around fish farms and causes deformities and mortality in juvenile European lobster (Homarus gammarus), a species commonly found in the vicinity of salmon farms in Norway. To date, there is no information on sub-lethal effects of teflubenzuron on, for example, behavior. We conducted an experiment to assess possible difference in the shelter seeking behavior of teflubenzuron-exposed (Nâ¯=â¯19) vs. not exposed (Nâ¯=â¯19) H. gammarus juveniles. The teflubenzuron-exposed juveniles had been given very low concentrations, 1.7⯵g per pellet twice per week for 113 days prior to this experiment. The concentration of teflubenzuron was estimated to be less than 1â¯ng/g lobster when they were tested in the behavior experiment. Animals were placed in a lane with a shelter at one end. Once a lobster had found and entered the shelter, they were repeatedly displaced back to the opposite end of the lane, for a total of 3 repeated runs per animal. Three of the exposed juveniles failed to settle in the shelter, and the remaining teflubenzuron-exposed animals took significantly more time to explore the environment and to find and recognize shelter. Furthermore, exposed lobsters also exhibited slower walking speed compared to the controls. These results demonstrate that teflubenzuron significantly reduces exploratory behavior, learning and activity of juvenile H. gammarus. Thus, exposure to teflubenzuron could increase predation mortality of juvenile lobsters in the wild.
Assuntos
Antiparasitários/toxicidade , Benzamidas/toxicidade , Nephropidae/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Aquicultura , Comportamento Animal/efeitos dos fármacos , Comportamento Exploratório/efeitos dos fármacos , Aprendizagem/efeitos dos fármacos , Nephropidae/fisiologia , NoruegaRESUMO
Increasing use of pharmaceutical drugs to delouse farmed salmon raises environmental concerns. This study describes an experiment carried out to elucidate the molecular mechanisms of the antiparasitic drug teflubenzuron on a non-target species, the European lobster. Juvenile lobsters (10.3±0.9 mm carapace length) were fed two environmentally relevant doses of teflubenzuron, corresponding to 5 and 20% of a standard salmon medication (10 mg/kg day), termed low and high dose in this study. After 114 days of dietary exposure, whole-animal accumulation of teflubenzuron was determined. One claw from each animal was collected for transcriptional analysis. Overall, exposed animals showed low cumulative mortality. Six animals, two from the low dose treatment and four from the high dose, showed exoskeletal abnormalities (claw deformities or stiff walking legs). Residual levels of teflubenzuron in juvenile lobster were 2.7-fold higher in the high dose (282 ng/g) compared to the low dose treatment (103 ng/g). The transcriptional examination showed significant effects of teflubenzuron on 21 out of 39 studied genes. At the transcriptional level, environmentally relevant levels of the anti-salmon lice drug impacted genes linked to drug detoxification (cyp3a, cyp6a2, cyp302a, sult1b1, abcc4), cellular stress (hsp70, hsp90, chh), oxidative stress (cat, gpx3) and DNA damage (p53), as well as molting and exoskeleton regulation (chi3l1, ecr, jhl1, chs1, ctbs, gap65, jhel-ces1) in claw tissue (muscle and exoskeleton). In conclusion, teflubenzuron at sub-lethal levels can affect many molecular mechanisms in European lobster claws.
Assuntos
Benzamidas/toxicidade , Regulação da Expressão Gênica/efeitos dos fármacos , Nephropidae/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Exoesqueleto/efeitos dos fármacos , AnimaisRESUMO
This study describes experiments carried out to examine effects of the antiparasitic drug teflubenzuron, used in delousing farmed salmon, on a non-target species, the European lobster (Homarus gammarus). Juvenile lobsters were fed two doses of teflubenzuron, 10 and 20mg/kg successively for 7 days corresponding to a standard medication of the fish (10mg/kg day) and twice the standard dose (20mg/kg day). Monitoring lasted 3 months to include at least one moulting period for all individuals. Cumulative mortality was higher in all replicates given medicated feed compared with the control group. Mean cumulative mortality for each dosing was 41 ± 13% for 10mg/kg and 38 ± 8% for 20mg/kg, i.e. no difference. Drug residue was analysed in all juveniles that died, in addition to 12 juveniles at day 8 and the first 12 surviving lobsters. A decline in concentration of teflubenzuron from over 8,000 ng/g (day 5) to 14 ng/g (day 70) was observed in the juveniles that died during the experiment. Twelve individuals that died contained 82 ng/g or less whereas the mean concentration in the first 12 lobsters that survived moulting was 152 ng/g. Following a single oral administration, the half-life of teflubenzuron in lobster was estimated to 3.4 days and the initial concentration (C0) to 515 ng/g at time t0. At the end of the study a considerable number of juvenile lobsters were observed with deformities in various organs; carapace, walking legs, cheliped, tail fan, abdomen and antenna. The occurrence of observed deformities varied from 0 to 15% in treated replicates and will most likely affect ability to locate and consume food (antenna, claw and walking legs), respiration (carapace) and ability to move/swim (walking legs, tail fan and abdomen). In total, the mortality and senescent damages were close to 50% in all replicates. Juveniles that survived medication without deformities however, moulted and increased in size at each moult equally well as the unmedicated controls.