EFFECT OF PREY SIZE SELECTION AND RATION ADDITION ON THE REARING OF PIRACANJUBA LARVAE, BRYCON ORBIGNYANUS

Efeito da seleção do tamanho da presa e da adição da ração no cultivo de larvas de piracanjuba, Brycon orbignyanus.   Larvas de piracanjuba, Brycon orbignyanus foram cultivadas em laboratório sendo submetidas a quatro tratamentos alimentares: 1) plâncton (P) selecionado em peneira de 1.000 mm; 2) plâncton e ração (PR) selecionados em peneira de 1.000 mm, sendo a ração introduzida a partir do terceiro dia de alimentação exógena. 3) plâncton selecionado (PS) em peneira de 350 mm, até o décimo dia, a partir de quando era selecionado com peneiras de 500 mm; e 4) plâncton e ração selecionados (PSR) em peneira de 350 mm, até o décimo dia, a partir de quando eram selecionados com peneiras de 500 mm, sendo a ração introduzida a partir do terceiro dia de alimentação exógena. As variáveis limnológicas, temperatura da água, oxigênio dissolvido, pH e condutividade foram similares entre os tratamentos, estando dentro da faixa adequada para à espécie. Os resultados sugerem que a seleção de tamanho da presa está positivamente correlacionada a taxa de sobrevivência das larvas, provavelmente devido ao decréscimo da hierarquia alimentar, que atenuou a heterogeneidade de crescimento e o canibalismo por conseqüência. A ração adicionada ao alimento também foi benéfica ao cultivo das larvas.   ABSTRACT   Piracanjuba larvae Brycon orbignyanus were reared in laboratory and fed the following four dietary treatments: 1) plankton (P) screened in 1,000 mm sieve; 2) plankton and ration (PR) screened in 1,000 mm sieve, plus ration starting on the third day of exogenous feeding; 3) plankton (PS) screened in 350 mm sieve, for the first ten days and in 500 mm sieve in the subsequent days; and 4) plankton and ration (PSR) screened in 350 mm sieve, during the first ten days and in 500 mm sieve in the subsequent days, plus ration starting on the third day of exogenous feeding. Limnological variables, water temperature, dissolved oxygen, pH and conductivity were similar in all treatments and within the range adopted for the species. The results suggest that prey size selection correlates positively with larvae survival rates, probably due to the decrease of alimentary hierarchy, thus attenuating growth heterogeneity and consequently, cannibalism. Ration added to natural food also proved to be beneficial.   Key words: larvae Brycon orbignyanus, plankton screened, ration.

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http://dx.doi.org/10.5007/2175-7925.2008v21n1p7O objetivo do presente trabalho foi testar a influência do meio à base de esterco suíno “in natura” e biodigerido, sobre o desenvolvimento, crescimento, comprimento total, peso seco e valor nutricional da microalga Ankistro desmus gracilis. O pico de crescimento para A. gracilis foi maior no meio biodigerido (6,2 x 107 células. mL-1) no volume de 2L. Alta porcentagem de lipídio foi observada no meio “in natura”, e, elevados teores de proteína no meio biodigerido em 2L. O biovolume, teor de cinzas e comprimento total foram diferentes (p < 0,05) entre os meios, o mesmo não ocorrendo para peso seco e fibra bruta (p > 0,05). O requerimento de luz foi diferente entre os meios, com menor intensidade para o esterco biodigerido (13,5μE.cm-2.s-1), indicando menor custo benefício. O meio a base de esterco suíno, mostrou bons resultados para o crescimento de A. gracilis, com qualidade de água adequada para cultivo, podendo ser utilizado para cultura em larga escala.Ankistrodesmus gracilis (Chlorophyta) fertilized in swine manure in the laboratory. The objective of the present work was to investigate the infl uence of swine manure media on the growth, total length, dry weight, and nutrit- ional value of Ankistrodesmus gracilis microalgae. Two media were mea- sured: “in natura” and biodigested. The growth rate peak for A. gracilis was highest with biodigester treatment (6.2 x 107 cells.mL-1) on the 5th day, at a volume of 2L. The highest percentage of lipids was verifi ed for “in natura” media. Protein was highest (p > 0.05) for the biodigested media at 2L. Biovolume, ash rate, and total length were different (p < 0.05) between treatments, but the same was not true for dry weight and crude fi ber (p > 0.05). Light demand was also different between media, with lesser intensity being required for biodigested media (13.5μE.cm-2.s- 1). In fact, the biodigested media proved to be cheaper in terms of cost and benefi t. Generally, the medium containing swine manure, both “in natura” and biodigested, showed better results in A. gracilis development, with water quality adequate for culture systems. Swine manure in both forms may also be used in high-density cultures in the laboratory

Efficiency of a constructed wetland for wastewaters treatment Eficiência de um "wetland" construído no tratamento de efluentes

AIM: The limnological characteristics of three different inlets water of the constructed wetland were compared in terms of concentration data and loading rate data and evaluated the removal efficiencies of nutrients, solids, BOD5, chlorophyll-a and thermotolerant coliforms (TC) by the treatment system; METHODS: The constructed wetland, measuring 82.8 m² and with detention time of 1 hour and 58 minutes in the rainy season and 2 hours and 42 minutes in the dry one, was provided with four species, Cyperus giganteus Vahl, Typha domingensis Pers., Pontederia cordata L. e Eichhornia crassipes (Mart.) Solms. The sampling sites evaluated in the dry (D) and rainy (R) seasons were: inlet water from aquaculture farm = IA; inlet channel of rainwater runoff = IR; inlet from UASB wastewater = IB; outlet wetland = OUT. The conductivity, pH, temperature, dissolved oxygen, alkalinity, BOD5, total soluble and dissolved solids, nitrogen, phosphorus, chlorophyll-a and TC were analyzed. Multivariate analyses, such as Cluster and Principal Components Analysis (PCA), were carried out to group sampling sites with similar limnological characteristics; RESULTS: In the PCA with the concentration data was retained 90.52% variability of data, correlating the inlet IB with high concentrations of conductivity, alkalinity, pH, TC, nutrients and solids. Regarding loading rate data, the PCA was retained 80.9% of the data's total variability and correlated the sampling sites IA D, IA R and OUT R with higher BOD5, chlorophyll-a, TDS, nitrate, nitrite, total-P, temperature, oxygen and water flow. The highest removal efficiencies rates occurred in the dry season, mainly in concentration, with 78% of ammonia, 95.5% of SRP, 94.9% of TSS and 99.9% of TC; CONCLUSIONS: The wetland was highly efficacious in the removal of nutrients, solids, BOD5, chlorophyll-a and TC, mainly during the dry season. The system restructuring to increase the detention time during the rainy season and a pre-treatment of UASB wastewater, can increase the retention of nutrients and solids by wetland.OBJETIVO: Comparar as características limnológicas de três diferentes entradas de água no "wetland" construído, com dados de concentração e carga, e avaliar a eficiência de remoção de nutrientes, sólidos, DBO5, clorofila-a e coliformes termotolerantes (TC) pelo sistema de tratamento; MÉTODOS: No "wetland" construído, com área total de 82.8 m² e tempo de residência de 1 hora e 58 minutos na estação chuvosa e 2 horas e 42 minutos na seca, foram utilizadas as espécies Cyperus giganteus Vahl, Typha domingensis Pers., Pontederia cordata L. e Eichhornia crassipes (Mart.) Solms. Os pontos de amostragem avaliados em períodos de seca (D) e chuva (R) foram: entrada de água proveniente de aquicultura = IA; canal de entrada de escoamento da chuva = IR; entrada de resíduos provenientes de biodigestores = IB; saída de água do "wetland" = OUT. As variáveis analisadas foram: condutividade, pH, temperatura, oxigênio dissolvido, alcalinidade, DBO5, sólidos particulados e dissolvidos, nitrogênio, fósforo, clorofila-a e TC. Análises estatísticas multivariadas de Agrupamento e Componentes Principais (ACP) foram usadas para agrupar pontos de amostragem com características limnológicas semelhantes; RESULTADOS: Na ACP com dados de concentração foi retido 90.52% da variabilidade dos dados, correlacionando a entrada IB com altas concentrações de condutividade, alcalinidade, pH, TC, nutrientes e sólidos. Para os dados de carga a ACP reteve 80.9% da variabilidade dos dados e correlacionou os pontos IA D, IA R e OUT R com elevada DBO5, clorofila-a, STD, nitrato, nitrito, P-total, temperatura, oxigênio e vazão. As maiores taxas de eficiência de remoção ocorreram na seca, principalmente em concentração, com 78% para amônia, 95.5% para SRP, 94.9% para STS e 99.9% para TC; CONCLUSÕES: O "wetland" foi eficiente na remoção de nutrientes, sólidos, DBO5, clorofila-a e TC, principalmente no período seco. Reestruturações do sistema para aumentar o tempo de residência durante as chuvas e um pré-tratamento dos resíduos de biodigestores, podem aumentar a retenção de nutrientes e sólidos pelo wetland

<b>Fish farm and water quality management</b> - doi: 10.4025/actascibiolsci.v35i1.10086

Fish farms’ water quality management is analyzed with regard to the management employed and the different trophic states are compared within the system during the dry and rainy seasons. Six sites were marked two in the water supply (P1 and P2), and four within the fish farm (P3 to P6) . Whereas sites P1 and P2 (water supply) were characterized as oligotrophic, the others were mesotrophic and eutrotrophic sites. Environmental variables, mainly nutrients, conductivity, COD, BOD5 and TSS tended to increase as from P3 due to management and fertilization. Greater impact has been registered in the fish farm under analysis for variables COD, ammonia, total phosphorus and TSS during the discharge and pond emptying period. Frequent monitoring of water quality should be undertaken in fish breeding and plankton production ponds, especially in those close to P3 and P4. Removal of sediment in decantation lake or P5 is also recommended to decrease nutrient concentrations, especially phosphorus, accumulated on the bottom soil

<b>Variações de nutrientes e estado trófico em viveiros seqüenciais de criação de peixes</b> - DOI: 10.4025/actascianimsci.v27i3.1218 <b>Nutrient and trophic state variations in continuous water flow fish ponds</b> - DOI: 10.4025/actascianimsci.v27i3.1218

O estudo avaliou o estado trófico e o aumento nas concentrações de nutrientes em viveiros seqüenciais em períodos de curta duração. Foram estudados seis viveiros de criação semi-intensiva de peixes que receberam efluentes de outros tanques em paralelo. As variáveis determinadas foram fósforo total, ortofosfato, amônia, nitrato, nitrito, clorofila-<em>a</em>, chumbo, cádmio, cobre, zinco, manganês, níquel, cromo, cálcio, ferro, potássio e magnésio, além do estado trófico dos viveiros. As amostras de água foram coletadas na nascente e entrada de cada viveiro nos períodos de chuva e seca. Foi encontrado um aumento no grau de trofia do primeiro em direção ao último viveiro e a distribuição seqüencial dos mesmos proporcionou um aumento gradativo nas concentrações de metais e clorofila-<em>a</em>. Os resultados obtidos no presente estudo indicam a necessidade de práticas de manejo ambiental através do desvio dos efluentes dos tanques em paralelo<br>This experiment evaluated trophic state and increase in nutrient concentrations in sequential fish ponds in short-term periods. Six semi-intensive fish ponds where studied and received effluents from other parallel ponds. The variables determined were: total phosphorus, orthophosphate, ammonia, nitrate, nitrite, chlorophyll-<em>a</em>, lead, cadmium, copper, zinc, manganese, nickel, chromium, calcium, iron, potassium and magnesium, in addition to the trophic state of the fish ponds. Water samples were collected in the well and at the inlet of each fish pond in rainy and dry periods. An increase in the trophic degree was found from the first to the last fishpond, and the sequential distribution provided a gradual increase in the concentrations of metals and chlorophyll-<em>a</em>. The results achieved in the present study indicate the need of environmental management practices through effluent deviation from parallel tank

Cultivo de Ankistrodesmus gracilis (Chlorophyta) em laboratório à base de esterco suíno

http://dx.doi.org/10.5007/2175-7925.2008v21n1p7 O objetivo do presente trabalho foi testar a influência do meio à base de esterco suíno “in natura” e biodigerido, sobre o desenvolvimento, crescimento, comprimento total, peso seco e valor nutricional da microalga Ankistro desmus gracilis. O pico de crescimento para A. gracilis foi maior no meio biodigerido (6,2 x 107 células. mL-1) no volume de 2L. Alta porcentagem de lipídio foi observada no meio “in natura”, e, elevados teores de proteína no meio biodigerido em 2L. O biovolume, teor de cinzas e comprimento total foram diferentes (p < 0,05) entre os meios, o mesmo não ocorrendo para peso seco e fibra bruta (p > 0,05). O requerimento de luz foi diferente entre os meios, com menor intensidade para o esterco biodigerido (13,5μE.cm-2.s-1), indicando menor custo benefício. O meio a base de esterco suíno, mostrou bons resultados para o crescimento de A. gracilis, com qualidade de água adequada para cultivo, podendo ser utilizado para cultura em larga escala

Physical, chemical and microbiological aspects during the dry and rainy seasons in a pond covered by macrophyte used in aquaculture water supply

AIM: The water quality of a pond covered by macrophytes and used as a water supply for aquaculture was evaluated during the dry and rainy seasons; METHODS: Six points were established for water sampling, at water inflow and outflow. Samplings were carried out monthly between June 2008 and May 2009; RESULTS: Inflow points P1, P2 and P3 in the pond had higher nutrient concentrations and high trophic rates. Moreover, capybaras in the area caused sediment suspension and an increase in fecal coliforms. There was significant difference (p < 0.05) in the concentrations of nutrients in water between the dry and rainy seasons. The outflow of water caused by rain carried the material around the pond directly into the water; CONCLUSIONS: The system studied was influenced by rain and lack of adequate management of the surrounding area. Water quality was deteriorated by increase in nutrient concentrations, fecal coliforms and reduction of dissolved oxygen in the water during the rainy season. This was due to allochthonous material from the area surrounding the pond that affected negatively the supply system