The overall objective of organic and inorganic fertilizers is to increase fish farm productivity. A common practice in fish farms is the fertilization of ponds to enhance algae growth and promote the production of zooplankton suitable for larvae. Several studies carried out in freshwater environments have established that the growth of phytoplankton may be controlled to a large degree by the limitation of nutrients, availability of light and the composition and abundance of zooplankton (Basualto et al., 2006).
Aim Examining whether small-scale tilapia cages have a potential influence on water abiotic parameters in a pond of a flow-through system. Methods Tilapia cages were installed near the pond water outlet. Samples for determination of abiotic parameters were monthly collected during eight months at five sampling sites: near three inlets receiving effluents from other fishponds (IW12, IW6 and IWM, the latter opening in a macrophyte bed), close to the cages in the open-pond (CC) and close to the water outlet (WO). The data were analyzed using Principal Component Analysis (PCA). Results The first PCA axis (70% of the data variability) was related to eutrophication and the second axis (20%) to the dependence of nitrifying bacteria on substrate availability. The sampling sites IW12, CC and WO showed high eutrophication levels. The lowest total phosphorus content, total suspended solids, hardness, alkalinity and conductivity and the highest dissolved oxygen were observed in the macrophyte bed area (IWM). Fish cages significantly increased total phosphorus content, conductivity, alkalinity and hardness in relation to the macrophyte bed inlet. Water outlet abiotic parameters were similar to near cage water. Conclusion The integrated cage-pond technology may be utilized in flow-through systems if incoming water quality (mainly in the site W12) is improved. Cages should be positioned closer to the pond center where it is deeper allowing higher flow-through and dispersion of uneaten feed residues and feces from the cages. This would avoid their deposition beneath cages and reduce their negatives influence on water quality entering the next fishpond (WO), and therefore not impair fish performance.
The present study was carried out to evaluate the phytoplankton community and water quality in four parallel fishponds (FP1 to FP4) during one year. Some abiotic parameters of water column and phytoplankton was sampled in four sites, one in each fishpond. Similarity analysis showed that FP2 fishpond was markedly different for the others ponds with regard to phytoplankton community. Conductivity, orthophosphate, temperature, TSS and hardness parameters were significantly different (p<0.05) between fishponds and all limnological parameters were significantly different (p<0.01) among period (months). Organic matter and phosphorus of the sediment were significantly different (p<0.01) only among fishponds. In current study Chlorophyceae and Bacillariophyceae occurred in most months. Cyanobacteria density in April and May was higher in all fishponds, at FP3 represented 71.4% in April and FP1 represented 78.7% in May of total reported, with chlorophyll-a content lower than 41 mg.L -1. The physical and chemical parameters of fishponds water constituted relations between the parameters and algae occurrence. The present study however, indicated that Cyanobacteria was more frequent in the fishponds after the fish grow-out period (April), and the water quality should be monitored more frequently in this period, due to the high total phosphorus, orthophosphate and chlorophyll-a contents.Keywords: algae, aquaculture, physical and chemical parameters, water quality. Variação sazonal dos parâmetros bióticos e abióticos em tanques de piscicultura com disposição paralela de região neotropicalResumo O presente estudo avaliou durante um ano a comunidade fitoplanctônica e os fatores abióticos da água de quarto tanques de piscicultura (FP1 ao FP4) com disposição paralela. Alguns fatores abióticos da água e do fitoplâncton foram amostrados em quarto pontos, localizados um em cada tanque de piscicultura. . Os parâmetros físico-químicos da água dos tanques de piscicultura apresentaram relação com a ocorrência do fitoplâncton nestes sistemas. Os resultados deste estudo indicaram a maior frequência de Cyanobacteria no período após a engorda de peixes (abril) necessitando maior monitoramento da qualidade da água devido aos altos teores de fósforo total, ortofosfato e clorofila-a observados neste mês (abril) Palavras-chave: alga, aquicultura, variáveis físicas e químicas, qualidade da água.
ABSTRACT.A laboratory culture of Ankistrodesmus gracilis algae was evaluated by studying the biology of the species and its chemical composition in a traditional medium (CHU 12 ) and in two alternative culture media, NPK (20-5-20) and macrophyte (Eichhornia crassipes) + NPK, in three different types of recipients (fiberglass, carboy and plastic bag).
Aim Limnological conditions, phytoplankton and zooplankton communities in a fishpond highly affected by management during the dry and rainy seasons are investigated. Methods Water samples were analyzed for physicochemical parameters; soil samples were analyzed for macro- and micro-nutrients, phytoplankton and zooplankton communities, at four sites, during eight months in the rainy and dry seasons. Distance-based linear model (DISTLM) was applied with Akaike Information Criterion (AIC), where the influence of environmental variables in the variation of phytoplankton and zooplankton composition could be assessed and the best model could be selected. Results The multiparameter test revealed that variables pH, TSS and TP better explain the composition of the biotic community (AICc = 45.6; R2 = 0.80). Chlorophyceae was the dominant group with 32 taxa, or rather, 75-85% of total phytoplankton, with high density at 2,365-4,180 ind.L-1 during the sampling period. Rotifera was the most abundant group in the zooplankton community during the two seasons, except at IW2 during the dry season, when Copepoda had a higher density, namely, 52% of total zooplankton community at this site. Conclusions The contribution of allochthonous material to the fishpond during the two seasons mainly consists of macro- and micro-nutrients and thermotolerant coliforms that influenced the plankton community and enhanced high Cyanobacteria density in the rainy season. Plankton community in the studied pond was characteristic of small water bodies. Management protocol in places with continuous water flow according to the region may be an important tool to optimize and to avoid risks in fish production.
Water samples, zooplankton community and sediment samples were analyzed at three sites in a pond receiving wastes, bi-weekly for seven months, covering the rainy and dry seasons. Water quality parameters failed to show significant differences between the sites for turbidity, total suspended solids, dissolved oxygen, transparency, conductivity, alkalinity and total phosphorous. Only temperature was different between the seasons. In the case of sediment, only aluminum (Al) was not different during the experimental period when highest calcium (Ca) concentrations were reported. The relative abundance of Rotifera during the sampling period reached 80-96% (rainy season) and 59-98% (dry season) in total zooplankton. Current study demonstrated that the water quality of shallow pond associated with allochthonous materials from aquaculture farm significantly influenced the structure of zooplankton assemblage due to high nutrient concentrations, conductivity, alkalinity and chlorophyll-a causing more fertilized water. However, heavy rains (February-April) and continuous water flow favored aeration (dissolved oxygen >5.2 ± 1 mg L-1). The use of pond water for agricultural irrigation or for other purposes, must be analyzed more effectively, avoiding problems caused by its usage.
Aim:The present investigation aims at evaluating attention to the occurrence and abundance of planktonic communities in fishponds and their relationships to the management employed; Methods: Seven fishponds (V 1 -V 7 ) fertilized with different treatments were analyzed by monthly sampling, taken between July and December/07, during both dry and rainy seasons; Results: Euglenophyceae and Chlorophyceae were most representative during the studied period. In the fishpond with organic fertilizer Cyanobacteria was more than 65 and 90% of total phytoplankton abundance in September and August, mainly represented by Microcystis sp. (14,595 and 22,500 ind.L -1 , respectively). An inverse relationship occurred between Copepoda and Cladocera, and Copepoda and Rotifera were present in all fishponds during the both seasons. Diversity (H') and species richness was low and equitability indices generally showed the highest values for zooplankton. The lowest values were observed for phytoplankton during the rainy season; Conclusions: The use of organic fertilizer and the random emptying of the fishponds affected directly and species diversity and richness, with dominance of Cyanobacteria emphasizing the need to adopt a management technique to increase fishponds productivity and consequently, fish production.Keywords: phytoplankton, zooplankton, fishponds, management.Resumo: Objetivo: O presente estudo objetivou avaliar a ocorrência e abundância da comunidade planctônica em viveiros de piscicultura em função do manejo adotado; Métodos: Foram estudados sete viveiros (V 1 -V 7 ) com diferentes tratamentos de fertilização, com amostras realizadas mensalmente de julho a dezembro/07, em duas épocas do ano: seca e chuva; Resultados: Em geral, Euglenophyceae e Chlorophyceae foram as mais representativas ao longo do período estudado. No viveiro com fertilizante orgânico, Cyanobacteria representou mais de 65 e 90% do total de organismos fitoplanctônicos ocorrido em setembro e agosto representado principalmente por Microcystis sp. (14.595 e 22.500 ind.L -1 , respectivamente). Relação inversa foi observada entre Copepoda e Cladocera, porém Copepoda juntamente com Rotifera estiveram presentes em todos os viveiros nas duas estações. A diversidade (H') e riqueza de espécies apresentaram baixos valores e, o índice de equitabilidade, em geral, foi elevado para o zooplâncton. Os valores mais baixos de equitabilidade para o fitoplâncton foram observados durante a estação chuvosa; Conclusões: O uso de fertilizante orgânico e o esvaziamento aleatório dos viveiros influenciaram diretamente na diversidade e riqueza de espécies, com dominância de Cyanobacteria, enfatizando a necessidade de adotar uma metodologia de manejo para aumentar a produtividade dos viveiros e consequentemente, a produção de peixes.Palavras-chave: fitoplâncton, zooplâncton, viveiros, manejo. Biological LimnologySipaúba-Tavares, LH., Millan, RN. and Amaral AA. Acta Limnologica Brasiliensia710 (V 2 ) and 6,550 m 2 (V 7 ), and mean depth was 1.50 m. Fishponds' water supply ...
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