Water quality and zooplankton in tanks with larvae of Brycon Orbignyanus (Valenciennes, 1949)

Abstract

Due to the importance of water variables conditions and available food in the development and survival of fish larvae, the current research evaluates the effects of two different food treatments (ration + zooplankton and only zooplankton) and water quality in tanks with Brycon orbignyanus larvae. Total water transparency (45 cm) has been mainly associated with short residence time, continuous water flow and shallowness. Dissolved oxygen ranged between 1.32 and 7.00 mg.L -1 in tanks with ration + zooplankton and between 1.82 and 7.60 mg.L -1 in tanks with only zooplankton treatments. Nutrients were directly affected by the addition of ration in water, with the exception of nitrite. Ten Rotifera species were found represented by high densities, ranging between 8.7 x 10 5 and 1.3 x 10 6 org.m -3 , throughout the experimental period (January to March/1996). Cladocera had the lowest density in the four tanks under analysis and ranged between 4.7 x 10 4 and 2.1 x 10 5 org.m -3 for the six species. Diaphanosoma birgei has been classified as the most frequent species. Since ration + zooplankton produced better larvae yield, this treatment is recommended for Brycon orbignyanus larvae.Keywords: Brycon orbignyanus, larvae tanks, limnology, zooplankton. Qualidade da água e zooplâncton em tanques de larvicultura deBrycon orbignyanus (Valenciennes, 1949) ResumoDevido à importância das condições das variáveis da água e do alimento disponível no desenvolvimento e sobrevivência das larvas de peixes, o objetivo deste estudo foi avaliar o efeito do uso de dois tratamentos alimentares (ração + zooplâncton e somente zooplâncton) e a qualidade da água, em tanques de larvicultura de Brycon orbignyanus. A transparência total da água (45 cm) esteve associada principalmente ao curto tempo de residência, fluxo contínuo e baixa profundidade. As concentrações de oxigênio dissolvido variaram de 1,32 a 7,00 mg.L -1 no tratamento contendo ração + zooplâncton, e de 1,82 a 7,60 mg.L -1 no tratamento contendo somente zooplâncton. Os nutrientes foram diretamente influenciados pela adição de ração no meio com exceção do nitrito. Rotifera apresentou a maior densidade, variando ao longo do período experimental de 8,7 x 10 5 a 1,3 x 10 6 org.m -3 entre os quatro tanques estudados, num total de dez espécies. A menor densidade foi observada para Cladocera, variando de 4,7 x 10 4 a 2,1 x 10 5 org.m -3 num total de seis espécies encontradas, sendo Diaphanosoma birgei a única espécie classificada como muito freqüente. O uso de ração junto com zooplâncton proporcionou melhor rendimento para larvas de B. orbignyanus.Palavras-chave: Brycon orbignyanus, tanques de larvicultura, limnologia, zooplâncton.

Trophic relationship between the Patinga hybrid (Piaractus mesopotamicus x Piaractus brachypomus) and Echinorhynchus gomesi Machado Filho, 1948 in fish farms

“…When zooplankton density was evaluated, Rotifera was shown to be dominant in P2, whereas Copepoda and Ostracoda groups were strongly represented in P1. In general, the zooplankton community can be influenced by water quality, food availability, ecological interactions (competition and predation between the organisms), and in the case of cultivation environments, tank management (Paes et al, 2011;Sipaúba-Tavares et al, 2008).…”

Conservation of Brycon orbignyanus natural populations and stocks for their reproductive, genetic, environmental sustainability: A model for species threatened with extinction

“…For example, Toledo et al (2003), when analyzing the water quality of a fi sh farm in the municipality of Alta Floresta-MT, found statistically signifi cant differences between the water supply to ponds and the water outfl ows from those ponds. On the other hand, Sipaúba-Tavares et al (2008), when analyzing the infl uence of water quality and zooplankton abundance on the performance of B. orbignyanus larvae, stated that the physical, chemical and biological variables of water determine the yield of larvae in ponds, necessitating the constant control and monitoring of this resource.…”

Microsatellite multiplex systems for Brycon orbignyanus (Characiformes: Bryconidae)

“…It suffers from several pressures such as intense hydroelectric exploitation in the basin, pollution, deforestation of riverine vegetation and introduction of species (Oliveira et al, 2017). Its omnivorous habits and fast growth curve under domestication (Sipaúba-Tavares et al, 2008;Nogueira et al, 2014) makes this fish a good candidate for the development of aquaculture programs, which could guarantee its ex situ cultivation and help in situ conservation initiatives. Hatchery production of this species, targeting stocking efforts in areas affected by dam introduction, is presumed to be important in helping maintaining small population remnants in some isolated points in the basin, but this is still unaddressed in rigorous scientific studies.…”