ABSTRACT
OBJECTIVE: To verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish. STUDY DESIGN: Clinical study, randomized, parallel, multi-arm with control group in target species. ANIMALS: A total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used. METHODS: Silver catfish and grass carp were exposed to different concentrations of citral, 15-675 and 15-600 µL L-1, respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 µL L-1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 µL L-1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment. RESULTS: Citral only induced sedation from 15, 25 and 40 µLL-1 in both species. Anesthesia without mortality was induced in silver catfish at 50-600 µL L-1 and grass carp at 75-450 µL L-1. At 675 and 600 µL L-1, mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Citral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish.
Subject(s)
Anesthetics , Carps , Catfishes , Oils, Volatile , Acyclic Monoterpenes , Anesthetics/pharmacology , Animals , Hypnotics and Sedatives/pharmacology , Palau , VerbenaceaeABSTRACT
ABSTRACT: Anesthetics are effective to reduce or minimize stress in handling operations related to fish cultures. Aiming to avoid residual effects of synthetic drugs, several natural agents, such as essential oils (EOs), have been tested. The aim of this study was to determine the optimal concentration of the EO of Ocimum micranthum for induction of anesthesia in juveniles of silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella). Results demonstrated that the most suitable concentration to sedate silver catfish and carp is 25μL/L, while to anesthetize 200μL/L is more suitable for silver catfish and 100μL/L for grass carp, because these concentrations induce deep anesthesia in less than three min and recovery in less than five min. Analysis of the EO constituents showed methyl chavicol, a compound with carcinogenic potential, as the major component (58.2%). Therefore, the EO of O. micranthum is not recommended for fish anesthesia if the fish are to be used as food.
RESUMO: Os anestésicos são eficazes para reduzir ou minimizar o estresse nas operações de manuseio relacionadas à piscicultura. Com o objetivo de evitar efeitos residuais de fármacos sintéticos, vários agentes naturais, como óleos essenciais (OEs), têm sido testados. O objetivo deste estudo foi determinar a concentração ótima do OE de Ocimum micranthum para a indução de anestesia em juvenis de jundiá (Rhamdia quelen) e carpa capim (Ctenopharyngodon idella). Os resultados demonstram que a concentração mais adequada para sedar jundiás e carpas capim é 25μL/L. Enquanto que para anestesiar 200μL/L é mais adequado para jundiás e 100μL/L para carpas capim, pois essas concentrações induzem anestesia profunda em menos de três minutos e recuperação em menos de cinco minutos. A análise dos constituintes do OE identificou o metil chavicol, um composto com potencial carcinogênico, como componente majoritário (58,2%). Portanto, o OE de O. micranthum não é recomendado para anestesia de peixes usado como alimento.
ABSTRACT
Os macroinvertebrados bentônicos têm sido amplamente utilizados como bioindicadores de qualidade ambiental. O objetivo deste estudo foi comparar a qualidade da água que sai de uma área com cultivo de arroz irrigado (água de drenagem) com a água de irrigação, oriunda do Rio Gravataí, em um ponto na grande Porto Alegre. Este estudo de monitoramento foi conduzido na Estação Experimental do Arroz, pertencente ao Instituto Rio Grandense do Arroz (IRGA), em Cachoeirinha, Rio Grande do Sul (RS), ao longo da safra de 2006/2007. Uma camada de 5cm de solo contendo macroinvertebrados bentônicos foi amostrada, utilizando um Corer (78,54cm²), na fonte de irrigação da lavoura (Rio Gravataí e Canal de Irrigação) e no receptor de seus efluentes (Canal de Drenagem). Além disso, o oxigênio dissolvido (O2) na água foi registrado em cada ponto. O material foi filtrado em uma peneira com malha de 0,5mm, fixado, triado e identificado. A abundância, riqueza, biodiversidade e equitabilidade foram avaliadas e comparadas entre os pontos amostrados. Tais parâmetros ecológicos demonstraram uma comunidade mais estruturada e complexa no canal de drenagem que no canal de irrigação e no Rio Gravataí, indicando que a qualidade ambiental é melhor no ponto que recebe a água que passa pela lavoura que nos pontos de entrada da água. Portanto, a comunidade de macroinvertebrados bentônicos neste estudo sugere que os efluentes produzidos pelas cidades e indústrias, como os presentes na bacia hidrográfica do Rio Gravataí, em especial da Grande Porto Alegre, são mais agressivos aos ambientes aquáticos que os efluentes drenados de uma lavoura manejada de acordo com as recomendações técnicas para a cultura.
The macroinvertebrates have been used as indicators of environmental quality. The objective of this study was to compare the quality of water which drains from the rice flooded crop (drainage water) with the irrigation water, sourced from Gravataí River, near the Porto Alegre City, using benthonic macroinvertebrate community as bioindicator. This study was carryout at the Rice Experiment Station of IRGA, in Cachoeirinha (RS), during the 2006/2007 harvest. A layer of 5cm soil, containing benthonic macroinvertebrate was sampled, using a Corer (78.54cm²), at the irrigation source (Gravatai River and Irrigation Channel) and at the effluents receptor (Drainage Channel). Oxygen dissolved (O2) in water also was registered in each point. The sampled material was filtered in a mesh sieve with f 0.5mm and fixed. The macroinvertebrates were identified and the ecologic parameters as abundance, richness, diversity and evenness were evaluated and compared among the sample points. Such ecologic parameters showed a more complex and structured community at the drainage channel, than at irrigation channel, and at Gravatai River, indicating that the environmental features is better in the point which received the water that pass through the crop, than at the irrigation points. Therefore, the benthic macroinvertebrate community in this study suggests that effects generated by cities and industries of Porto Alegre region are more aggressive to aquatic environments than that promoted by rice crop managed according to the technical guidelines.
