ABSTRACT
This study evaluated the influence of intensive farming of tilapia on physical and chemical parameters and on the occurrence of Streptococcus spp. in the water of the lake and of cages. Throughout a year, monthly samplings were taken in the rainy and dry seasons for a year, at two sampling sites, lake and net cages. For the determination of water quality, physical and chemical water parameters were evaluated and compared to the standards established by Conama Resolution no. 357/2005. The presence of Streptococcus spp. in the water was determined by plating on blood Agar and biochemical screening. Mean values of water parameters were tested using the Kruskal-Wallis test comparing sampling sites and seasons. Ammoniacal nitrogen (ammoniacal-N), total phosphorus (total-P) levels and occurrence of Streptococcus spp. have increased in the water of the net cages. The mean values of several parameters have decreased during the rainy period, except for pH, temperature and ammoniacal-N. Total-P and dissolved oxygen levels, during dry and rainy periods, respectively, exceeded the standard established for freshwater class 2, recommended for aquaculture, which can be harmful to the fish. Therefore, constant monitoring of the physical,chemical and microbiological water parameters is recommended since the Juara lake is also used for recreational purposes.
Este estudo avaliou a influência de uma criação intensiva de tilápias na alteração dos parâmetros físico-químicos e ocorrência de Streptococcus spp. na água. Durante um ano em dois períodos, seco e chuvoso, as amostras de água foram colhidas mensalmente em dois locais, lagoa e tanques-rede. Parâmetros físico-químicos para determinar a qualidade da água foram avaliados por indicadores estabelecidos na Resolução Conama n. 357/2005. A presença de Streptococcus spp. na água foi verificada por plaqueamento em ágar sangue e triagem bioquímica. Os dados foram analisados pelo teste de Kruskal-Wallis comparando-se as médias dos locais e dos períodos de amostragem. Verificou-se aumento da concentração de nitrogênio amoniacal (N-amoniacal), fósforo total (P-total) e Streptococcus spp. na água dos tanques-rede. No período chuvoso houve redução de vários parâmetros, exceto pH, temperatura e N-amoniacal. A concentração de P-total no período seco e do oxigênio dissolvido no período chuvoso excedeu o padrão estabelecido para água doce classse 2, recomendado para aquicultura, fato que pode prejudicar a criação de peixes. Diante do exposto, recomenda-se o monitoramento dos parâmetros físico-químicos e microbiológico da água, visto que a lagoa Juara é utilizada também para fins recreativos.
Subject(s)
Aquaculture , Streptococcus , TilapiaABSTRACT
This study evaluated the influence of intensive farming of tilapia on physical and chemical parameters and on the occurrence of Streptococcus spp. in the water of the lake and of cages. Throughout a year, monthly samplings were taken in the rainy and dry seasons for a year, at two sampling sites, lake and net cages. For the determination of water quality, physical and chemical water parameters were evaluated and compared to the standards established by Conama Resolution no. 357/2005. The presence of Streptococcus spp. in the water was determined by plating on blood Agar and biochemical screening. Mean values of water parameters were tested using the Kruskal-Wallis test comparing sampling sites and seasons. Ammoniacal nitrogen (ammoniacal-N), total phosphorus (total-P) levels and occurrence of Streptococcus spp. have increased in the water of the net cages. The mean values of several parameters have decreased during the rainy period, except for pH, temperature and ammoniacal-N. Total-P and dissolved oxygen levels, during dry and rainy periods, respectively, exceeded the standard established for freshwater class 2, recommended for aquaculture, which can be harmful to the fish. Therefore, constant monitoring of the physical,chemical and microbiological water parameters is recommended since the Juara lake is also used for recreational purposes.
ABSTRACT
Foi analizada a composiçäo centesimal de uma multimistura no intuito de determinar a quantidade de materiais contidos. Com a posse dos dados obtidos, constatou-se que a mistura possui alto teor de proteína, lipídio e ferro, sendo porém pobre em fósforo e cálcio