Efeito da composição iônica da água no desenvolvimento de larvas de Macrobrachium rosenbergii (De Man, 1879) no estágio II

The importance of the ions presence in water Ca2+, K+, HCO3-, Br-, Sr2+, Mn2+, HPO42-, Li+, MoO42-, S2O32-, Al3+, Rb+, Zn2+, Co2+ and Cu2+ on the development of Macrobrachium rosenbergii at the larval stage II was evaluated, in order to obtain information to optimize the ionic composition of the brackish water used to larviculture this species. Artificial sea water was prepared according to the formulation used by the Crustacean Rearing Laboratory of CAUNESP. In this formula, salts are classified in major elements, minor elements and trace elements. In this experiment, a starvation test was applied. It consisted in keeping larvae of M. rosenbergii, at the stage II, in 30 ml beakers containing 15 ml of brackish water (12‰). The beakers were kept at about 30ºC of controlled air temperature. There were five phases conducted sequencially (phases 1 to 5). Brackish water of different ionic composition, in relation to the trace elements Al3+, Rb+, Zn2+, Co2+ and Cu2+, were evaluated on the first two phases. Differents formulas containing the minor elements Br-, Sr2+, Mn2+, HPO42-, Li+, MoO42- and S2O32 were evaluated on phases 3 and 4. And five media with differents ionic composition containing the major elements Ca2+, K+, HCO3-, and the minor element Br-, were evaluated on phase 5. Three beakers were used per treatment, and each was stocked with six larvae, in a complete randomized experimental design. In order to estimate the average life time, the number of larvae that survived the treatment was counted every eight hours. The data were analyzed through ANOVA and the means were compared by the Tukey test. The trace elements Al3+, Rb+, Zn2+, Co2+ and Cu2+ and the minor elements Sr2+, Mn2+, HPO42-, Li+, MoO42- and S2O32 did not allow an increase of the larvae life time at the second larval stage. These ions could, however, become essential to this organism at the other stages, or could show a retardation effect. Sodium thiosulphate must be addedO trabalho teve como objetivo avaliar a importância da presença na água dos íons Ca2+, K+, HCO3-, Br-, Sr2+, Mn2+, HPO42-, Li+, MoO42-, S2O32-, Al3+, Rb+, Zn2+, Co2+ e Cu2+ para o desenvolvimento do Macrobrachium rosenbergii no estágio larval II, visando fornecer subsídios para a otimização da composição iônica da água salobra utilizada na larvicultura dessa espécie. A água do mar artificial foi preparada conforme a formulação usada no setor de Carcinicultura do CAUNESP, cujos sais são classificados em macroelementos (MA), microelementos (MI) e elementos traços (ET). Foram realizadas cinco etapas seqüencialmente. Na primeira avaliaram-se águas salobras preparadas com MA + MI + ET, sendo que, em cada tratamento, foi eliminado um dos seguintes elementos traços: alumínio, rubídeo, zinco, cobalto e cobre. Na segunda a água foi preparada com MA + MI e, em cada tratamento adicionou-se um dos elementos traços. Na Fase 3 foram analisadas formulações preparadas com MA + MI, sendo que, em cada tratamento foi eliminado um dos seguintes microelementos: bromo, estrôncio, manganês, fosfato, lítio, molibdato e tiossulfato. Na Fase 4 a água foi preparada com MA e, em cada tratamento, adicionouse um dos microelementos. Na última fase foram avaliados cinco meios preparados com MA + Br-; em cada tratamento foi eliminado um dos seguintes íons: cálcio, potássio, bicarbonato e brometo. Todas as etapas foram realizadas seguindo um delineamento inteiramente casualizado com três repetições (três béqueres) para cada tratamento. Aplicou-se um teste de inanição, que consistiu na estocagem de seis larvas de M. rosenbergii, no estágio larval II, em béqueres de 30 ml, contendo 15 ml de água salobra a 12‰, mantidos em temperatura ambiente em torno de 30ºC. A cada oito horas contou-se o número de larvas vivas em cada unidade experimental, para o cálculo do tempo médio de vida em todos os tratamentos. Os dados foram..

Concentrações de amônia, nitrito e nitrato em larvicultura do camarão Macrobrachium rosenbergii (De Man), realizada em sistema fechado com água salobra natural e artificial

Variations of ammonia, nitrite and nitrate in a recirculating M. rosenbergii (Crustacea, Decapoda) hatchery, reusing natural and artificial brackish water, in two successive cultures, were studied. Ammonia and nitrite values oscillated between 1.1 to 74.0 µg/l and 1.1 to 34.6 µg/l, respectively, and did not differ among the tested water types. Nitrate concentrations (N) increased similarly with time (T), according to a linear model (N = 0,241T – 0,734) with both natural and artificial water. Data suggested that the use and reuse of the artificial water did not affect the nitrification process. Therefore, it can be used in recirculating systems for M. rosenbergii hatchery.Avaliou-se o efeito da água salobra natural e artificial e da sua utilização em dois cultivos consecutivos sobre as concentrações de amônia, nitrito e nitrato, em sistema fechado de larvicultura de M. rosenbergii (Crustacea, Decapoda). A amônia oscilou entre 1,1 e 74,0 µg/l e o nitrito entre e 1,1 e 34,6 µg/l; estes não diferiram entre os tipos de água analisados. A concentração de nitrato (N) aumentou ao longo do tempo (T) de forma similar na água natural e artificial, seguindo um modelo linear (N = 0,241T – 0,734). Os resultados indicaram que a água salobra artificial não alterou o processo de nitrificação, tampouco o comportamento das principais variáveis ambientais. A reutilização da água também não produziu nenhum efeito negativo sobre essas variáveis. A fórmula de água do mar artificial aqui apresentada pode ser, portanto usada em sistemas de recirculação para a produção de pós-larvas de M. rosenbergii em até dois cultivos consecutivos

Efeito da composição iônica da água do mar artificial no desenvolvimento de larvas de Macrobrachium rosenbergii - DOI: 10.4025/actascibiolsci.v20i0.4484

The importance of the ions Ca2+, K+, HCO3-, Br-, Sr2+, Mn2+, HPO42-, Li+, MoO42-, S2O32-, Al3+, Rb+, Zn2+, Co2+ and Cu2+ in water on the development of Macrobrachium rosenbergii at the larval stage II was evaluated. A starvation test was applied. It consisted in keeping larvae of M. rosenbergii in beakers containing 15ml of brackish water (12‰) with different ionic compositions. In order to estimate average life time, larvae which survived the treatment were counted every eight hours. Elements Al3+, Rb+, Zn2+, Co2+,Cu2+, Sr2+, Mn2+, HPO42-, Li+, MoO4M2- and S2O32 were not effective on the larvae life time, whereas K and Ca2+ were the most important ions for larvae development, followed by Br- and HCO3-, respectively. These ions are indispensable in water and larvae must have an efficient mechanism to absorb them.Avaliou-se a importância da presença na água dos íons Ca2+, K+, HCO3-, Br-, Sr2+, Mn2+, HPO42-, Li+, MoO42-, S2O32-, Al3+, Rb+, Zn2+, Co2+ e Cu2+ para o desenvolvimento do Macrobrachium rosenbergii no estágio larval II. Aplicou-se um teste de inanição, que consistiu na estocagem das larvas em béqueres contendo 15ml de água salobra (12‰), de diferentes composições iônicas. A cada 8 horas contou-se o número de larvas vivas e calculou-se o tempo médio de vida em todos os tratamentos. Os elementos Al3+, Rb+, Zn2+, Co2+, Cu2+, Sr2+, Mn2+, HPO42-, Li+, MoO42- e S2O32- não influenciaram o tempo de vida das larvas. O K+ e o Ca2+ foram os íons mais importantes para o desenvolvimento das larvas, seguidos pelo Br- e pelo HCO3-, respectivamente, a presença desses íons no meio é indispensável e as larvas devem apresentar mecanismos eficientes de absorção desses elementos

Larval development of the giant river prawn Macrobrachium rosenbergii at different ammonia concentrations and pH values

The effect of ammonia and pH levels on giant river prawn Macrobrachium rosenbergii larvae were evaluated to provide science-based information on safe levels of ammonia and pH for larviculture. Survival rate, developmental stage, and larval weight gain were determined for larvae kept in water with total ammonia (NH4-N) concentrations of 0, 1, 2, 4, and 8 mg\L and pH 7, 8, and 9. The trials were conducted in two phases: phase 1, larvae from stages I through VIII and phase 2, larvae from stage VIII until metamorphose. Oxygen consumption was determined for larvae in stages I and VIII at total ammonia concentrations of 0, 4, and 8 mg/L and pH 8. Survival rate up to stage VIII varied from 86 to 98% and did not differ for total ammonia concentrations in pH 7 and 8 and for 0 mg/L NH4-N in pH 9. Survival rate was significantly lower (0-20%) for total ammonia concentrations from 1 to 8 mg/L (0.43-3.41 mg/L of unionized ammonia) in pH 9. Larval stage indexes (7.9-8.0 range) and weight gain (1.572-2.931 mg range) of larvae at the end of phase 1 of the experiment did not differ for the different ammonia concentration solutions, but were significantly lower in pH 9. In phase 2, no parameter differed among treatments for pH 7 and 8; however there was total mortality at pH 9 until 96h. Respiration rates diminished when larvae were exposed to total ammonia concentrations of 4 and 8 mg/L (0.28 and 0.55 mg/L of unionized ammonia), but development remained unaltered. Therefore, M. rosenbergii larvae tolerate high levels of total ammonia, while toxicity depends primarily on unionized ammonia concentrations. In addition, alkaline pH (9) acted directly on the larvae, curbing development and causing severe mortality. Larval tolerance to high ammonia and pH levels decreases for the last zoeal stages. © Copyright by the World Aquaculture Society 2005

Effects of nitrate concentration on larval development of the giant river prawn, Macrobrachium rosenbergii

The effect of nitrate concentration on giant river prawn, Macrobrachium rosenbergii, larvae was investigated. Survival rate, weight gain, and larval development were evaluated for different concentrations of nitrate in three experiments. The experiments were divided i n to two phases. In the first phase, larvae from stages I through VIII were analysed, while in the second phase larvae from stage VIII through post-larvae metamorphosis were analysed. Oxygen consumption was also determined for zoea I, II, and VIII exposed to 0, 700, and 1,000 mg/L of nitrate-N. No effect was observed for concentrations up to 180 mg/L NO3-N (experiments I and II), and nitrate levels as 1,000 mg/L NO3-N did not affect survival in the first phase of the third experiment. On the other hand, larval stage index (LSI) and weight gain decreased as nitrate-N concentration increased from 0 to 1,000 mg/L. In the second phase, survival and metamorphosis rate decreased as nitrate concentration increased, according to a linear model. The effect of nitrate levels on weight gain followed a curvilinear pattern. Larval respiration decreased in the water where nitrate was added, but only during stage II. The results demonstrated that nitrate presents extremely low toxicity for giant river prawn larvae, and data were related to the levels of nitrate that usually occur in larviculture systems also discussed. Therefore, nitrate is not a limiting factor for giant river prawn larviculture. © 2003 by The Haworth Press, Inc. All rights reserved

Sistema de recirculação e rotina de manejo para larvicultura de camarões de água doce Macrobrachium rosenbergii em pequena escala

A recirculating system and a matching management schedule for small-scale freshwater prawn larviculture were described. The system comprised a 140 L larval culture tank in line with a 43 L biofilter filled with 24 L of calcareous substrate. Both the tank and biofilter were made of black colored fiberglass in a conical-cylindrical shape. The turnover rate of the water through the system was 24 times a day; water was pumped by airlift. Results of ten larvicultures showed that the system maintained temperature, dissolved oxygen, pH, salinity, ammonium and nitrite stable and suitable to Macrobrachium rosenbergii larvae. Survival and productivity varied from 60.5 to 72.4% and 37 to 72 post-larvae/L, respectively; both were compatible with results of commercial hatcheries. Therefore, this system may be very useful for research purposes or adapted for small-scale post-larvae production

<b>Influence of a net cage tilapia culture on the water quality of the Nova Avanhandava reservoir, São Paulo State, Brazil</b> - doi: 10.4025/actascibiolsci.v34i3.7298

<p class="aresumo">In order to understand the influence of a net cage tilapia culture on the environment, water quality parameters were investigated during the period between December, 2005 and November, 2007. Three sampling stations were established in the reservoir of Nova Avanhandava (Zacarias, São Paulo State) as follows: upstream of net cage area (P1), in the rearing place (P2) and downstream of net cage area (P3). The mean values of the parameters examined in the water sampling stations were within the standards of water quality recommended by resolution no. 357/2005 of the Conselho Nacional do Meio Ambiente for class 2 freshwater bodies. A significantly higher mean concentration of total phosphorus (p < 0.05) in the P2 (0.035 mg L^-1) was the result of the uneaten feed and feces of fish. The average concentration of total phosphorus in P3 was lower (0.015 mg L^-1), which was assimilated by the aquatic ecosystem. The frequent monitoring of the water parameters is fundamental, so the producer can adjust the management according to environmental conditions, by reducing fish density or changing feeding rates for example, to mitigate or avoid water quality deterioration.</p><p class="apalavrachave"> </p

Influence of stocking densities in the nursery phase on the growth of Macrobrachium amazonicum reared in net pens

The Amazon river prawn (Macrobrachium amazonicum) is a native species with great potential for aquaculture, based on promising results obtained from experimental culture trials in Brazil. The influence of different stocking densities on the development of prawns reared in cages in the nursery phase as well as on their growth when transferred to grow-out net pens at lower densities was evaluated. In the nursery phase, juveniles I (0.157 +/- 0.014 g, 47 days old) were stocked in 0.5 m(-2) cages at densities of 400, 800 and 1200 m(-2). After 71 days, prawns were transferred to grow-out net pens of 2.0 m(-2), at a density of 20 juveniles II m(-2). The treatments were determined by the mean weights registered for the prawns (118 days old) previously stocked at 400, 800 and 1200 juveniles I m(-2) in the nursery phase: 0.94 +/- 0.07 g (T1), 0.61 +/- 0.04 g (T2) and 0.48 +/- 0.07 g (T3), respectively. In the nursery phase, mean survival was above 96%, whereas mean weights were significantly higher (P<0.05) for the density of 400 prawns m(-2). The highest biomass (276.7 g) and productivity (1152 juveniles II m(-2)) were registered at the density of 1200 prawns m(-2), differing significantly (P<0.05) from the lower densities. One month after the transfer of the animals to the net pens, there was recovery in the specific growth rate (SGR) of prawns in all treatments which was significantly higher (P<0.05) in T3 (4.01 +/- 0.36% day(-1)) and T2 (3.60 +/- 0.18% day(-1)). The feed conversion efficiency (FCE) in the first month after the transfer was also significantly higher (P<0.05) in T3 (78.2 +/- 19.1%) when compared to T1 (39.8 +/- 9.5%). These results suggest the occurrence of a compensatory growth in M. amazonicum after transferring them to lower densities, which can point out high densities for nursery cages as a viable practice. After 277 days of grow-out phase in net pens in the cold season, survival, mean weight and biomass did not differ significantly among the treatments, indicating the viability of using net pens in stocking prawns during autumn and winter, since the minimum temperature does not drop below 17 degrees C. Influence of stocking density during the nursery phase on the grow-out of prawns was not observed. The population structure in prawns reared in net-pens was similar to that observed in earthen ponds. (C) 2012 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP