The objective of this study was to evaluate the effects of garlic (Allium sativum) essential oil on the rates of eggs fertilization and hatching and on the normal development of larvae of artificially incubated silver catfish (Rhamdia quelen). The experiment was carried out using a completely randomized experimental design with four treatments and five replicates. The treatments consisted of introducing garlic essential oil into the incubators, which used a closed system of water recirculation, at concentrations of 0, 1, 3, and 5mg L-1. Rates of eggs fertilization and larval hatching were determined at 10 and 24h after the beginning of eggs hydration. Morphology of larvae was assessed with the aid of a stereo microscope to determine the rate of normal development. The concentration of 5mg L-1 promoted better rates of eggs fertilization and larval hatching. Concentrations of garlic essential oil had a linear effect on eggs fertilization rates and larval hatching. Garlic oil did not influence the morphology of the larvae (P>0.05). It is recommended to use 5mg L-1 of garlic essential oil to promote better rates of eggs fertilization and larval hatching of artificially incubated silver catfish.
This study aimed to evaluate the characterization and bioaccumulation of metals of the golden mussel encrusted in the screens of net cages installed in the reservoir of Itaipu Binacional. The experimental design was completely randomized, composed of two types of screens (PVC and Bezinal) distributed on four sides (Sides I, II, III, and IV) of the net cage. The total mass, the average mass, and the dimensions (width, height, and length) of the mollusks were evaluated. The mussels adhered to the Bezinal screen presented a higher average mass, length, height, and width than those colonized on the PVC screen (p <0.05). However, the PVC screen provided a greater (p <0.05) total mass of encrusted mussels. Regardless of the screen used, the average mass and length of mussels had higher values on Side I (p <0.05) than to the Sides II and IV, but not different from Side III. The mussels evaluated showed high levels of metals, and those encrusted in the Bezinal screen presented higher levels of Al, Zn and Cr than the individuals on the PVC screen (p <0.05). The use of a Bezinal screen is more efficient than a PVC screen, as an antifouling material. Mussels with shorter lengths had a higher incidence on the PVC screen. The mussels encrusted in the Bezinal screen bioaccumulate higher content of Al, Zn, and Cr. The type of screen used in the net cages influences the mass and size of adhered mussels, as well as can interfere with the metal accumulation in the golden mussel.
Este estudo teve como objetivo avaliar o efeito dos probióticos dietários (Bacillus cereus var. Toyoi e Bacillus subtilis C-3102) sobre a resposta hematológica, perfil bioquímico de glicose e cortisol, e prevalência ectoparasitária em tilápia-do-Nilo, variedade GIFT. Utilizou-se quatro dietas (D1 = basal sem adição de probióticos; D2 = basal + B. cereus; D3 = basal + B. subtilis; D4 = basal + B. subtilis e B. cereus) e cinco repetições. Foram utilizados 1000 juvenis de tilápia (60,56 ± 7,74 g), distribuídos aleatoriamente em 20 tanques de alvenaria com fundo de solo argiloso. Após 201 dias de cultivo os valores médios de hemoglobina dos peixes que receberam dietas com B. cereus foram superiores (P<0,05) aos arraçoados apenas com dieta basal. Não houve diferenças significativas nos valores de hematócrito, eritrócito, volume corpuscular médio, variação no tamanho das hemácias e concentração de hemoglobina corpuscular média de tilápias submetidas a dietas probióticas (P>0,05). O perfil bioquímico de glicose e cortisol, leucograma e prevalência parasitária dos peixes não foram influenciados (P>0,05) pela inclusão dos probióticos B. cereus e B. subtilis nas dietas. Independentemente das dietas contendo probióticos, há um local de preferência para os parasitas Monogenea (P<0,001) nas brânquias, enquanto a pele e nadadeiras foram os órgãos mais afetados por Trichodina spp. (P<0,001). A adição de probióticos Bacillus cereus e/ou Bacillus subtilis na dieta de tilápia-do-Nilo não foi capaz de beneficiar o perfil bioquímico de glicose e cortisol e perfil hematológico da série branca e vermelha dos peixes ao final do cultivo.
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