Streptococcus spp. e Aeromonas spp. na água e em tilápias do nilo (Oreochromis niloticus) e parâmetros físico-químicos da água de piscicultura em tanques-rede
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Data
2011-07-01
Autores
Suhet, Maria Isabel [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A criação intensiva de peixes tem se tornado popular, mas a dependência de arraçoamento pode enriquecer o ambiente com nutrientes, comprometendo a qualidade da água e predispondo os peixes a doenças. Streptococcus e Aeromonas são bactérias que acometem peixe em criações intensivas, podendo ocasionar mortalidade. Nesse sentido, o presente trabalho objetivou avaliar a influência de uma criação de tilápias do nilo em tanques-rede nos parâmetros de qualidade da água e na ocorrência de Streptococcus spp. e Aeromonas spp. na água e nos peixes em uma lagoa na região Sudeste do Brasil. Foram definidos para as amostragens dois locais, a lagoa, para coleta de água e os tanques-rede, para coleta de água e peixes e dois períodos, seco e chuvoso. Os dados obtidos da qualidade da água foram avaliados por indicadores estabelecidos na Resolução Conama nº 357, para corpos de água doce de classe 2. A presença de Streptococcus spp. e Aeromonas spp. foi avaliada por identificação fenotípica e a identificação das espécies, por provas bioquímicas. Isolados foram avaliados para produção de hemolisina utilizando ágar sangue e teste de resistência a antimicrobianos conforme o método de difusão de discos. A atividade de criação intensiva de peixes aumentou a concentração de fósforo total da água no período seco, ocorrência de Streptococcus spp. no ambiente e a população de Aeromonas spp. na superfície dos peixes. No período chuvoso, houve maior isolamento das espécies potencialmente patogênicas, Aeromonas hydrophila na superfície e no rim dos peixes, A. caviae, A. sobria, A veronii, A. jandaei e Streptococcus agalactiae na superfície dos peixes, quando também ocorreu aumento da concentração de N-amoniacal e depleção acentuada da concentração de oxigênio dissolvido na água, e isso pode ter sido a causa da mortalidade de peixes nos tanquesrede...
Intensive fish farming is becoming more and more popular, but dependency on ration feeding increases nutrient load of the water, affects its quality and predisposes fish to diseases. Streptococcus and Aeromonas are bacteria that can affect fish in intensive farms and cause mortality. This study aims at evaluating the impact of a nile tilapia net-cage farm on the water quality parameters and the occurrence of Streptococcus spp. and Aeromonas spp. in the water and on the fish, in a pond in Southeastern Brazil. Two sampling sites were defined, one in the pond and another in the net cages to collect water, and water and fish, respectively. Sampling took place during two periods, dry and rainy. Water quality data were analyzed according to standards set by Conama resolution nº 357, for freshwater bodies class 2. Streptococcus spp. and Aeromonas spp. were determined by phenotypic and species identification using biochemical tests. Isolates were evaluated for hemolysin production using blood agar and antimicrobial resistance test according to disk diffusion method. Intensive fish farming increased the amount of phosphorus in water, Streptococcus spp. occurrence in the environment and Aeromonas spp. population on fish surface as well, during dry periods. During the rainy season, more potentially pathogenic bacteria were isolated such as, Aeromonas hydrophila on fish surface and kidneys, A. caviae, A. sobria, A veronii, A. jandaei and Streptococcus agalactiae on fish surface. An increase of N-ammoniacal was also observed together with severe depletion of dissolved oxygen, which may have caused fish mortality in the net-cages. Production of b-hemolysis was greater for aeromonas species isolated from the water and fish kidneys, while for streptococci it was higher in isolates from fish surface. The species Aeromonas veronii, A. hydrophila, A. jandaei, A. sobria A. caviae and Streptococcus agalactiae... (Complete abstract click electronic access below)
Intensive fish farming is becoming more and more popular, but dependency on ration feeding increases nutrient load of the water, affects its quality and predisposes fish to diseases. Streptococcus and Aeromonas are bacteria that can affect fish in intensive farms and cause mortality. This study aims at evaluating the impact of a nile tilapia net-cage farm on the water quality parameters and the occurrence of Streptococcus spp. and Aeromonas spp. in the water and on the fish, in a pond in Southeastern Brazil. Two sampling sites were defined, one in the pond and another in the net cages to collect water, and water and fish, respectively. Sampling took place during two periods, dry and rainy. Water quality data were analyzed according to standards set by Conama resolution nº 357, for freshwater bodies class 2. Streptococcus spp. and Aeromonas spp. were determined by phenotypic and species identification using biochemical tests. Isolates were evaluated for hemolysin production using blood agar and antimicrobial resistance test according to disk diffusion method. Intensive fish farming increased the amount of phosphorus in water, Streptococcus spp. occurrence in the environment and Aeromonas spp. population on fish surface as well, during dry periods. During the rainy season, more potentially pathogenic bacteria were isolated such as, Aeromonas hydrophila on fish surface and kidneys, A. caviae, A. sobria, A veronii, A. jandaei and Streptococcus agalactiae on fish surface. An increase of N-ammoniacal was also observed together with severe depletion of dissolved oxygen, which may have caused fish mortality in the net-cages. Production of b-hemolysis was greater for aeromonas species isolated from the water and fish kidneys, while for streptococci it was higher in isolates from fish surface. The species Aeromonas veronii, A. hydrophila, A. jandaei, A. sobria A. caviae and Streptococcus agalactiae... (Complete abstract click electronic access below)
Descrição
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Água - Qualidade, Lagoas, Análise microbiologica, Antimicrobianos, Hemolisina, Antimicrobial, Hemolysin, Microbiological analysis, Pond, Water quality
Como citar
SUHET, Maria Isabel. Streptococcus spp. e Aeromonas spp. na água e em tilápias do nilo (Oreochromis niloticus) e parâmetros físico-químicos da água de piscicultura em tanques-rede. 2011. ix, 94 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2011.