Influence of management on plankton community of fishponds during the dry and rainy seasons

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 (V1-V7) 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.

Microcystin-LR in Brazilian Aquaculture Production Systems

The growth of aquaculture production systems, mostly the sport-fishing kind, coupled with a lack of control, brings about concerns on the quality of water and food produced. The current paper determines which factors may trigger the growth of cyanobacteria, with subsequent concentrations of microcystins in collected water samples, at the surface and in the water column, from 10 aquaculture systems, during the dry and rainy seasons. The above is undertaken by measurements of biotic (counting of Chlorophyceae, cyanobacteria, and microcystin-LR [MC-LR]) and abiotic (total nitrogen and total phosphorus) factors. Because the water from the 10 aquaculture production systems had MC-LR concentrations that were highly correlated with Microcystis aeruginosa (M. aeruginosa) biomass, most MC-LR microcystins were produced by this species. The MC-LR concentrations and M. aeruginosa counting were positively correlated with nitrogen-to-phosphorus ratios and suggest that parameters may affect not only the M. aeruginosa biomass, but also MC-LR concentrations. Water Environ. Res., 82, 240 (2010).

Characterization of a plankton community in a fish farm

Aim: The objective of this study was to analyze the composition of phytoplankton and zooplankton communities related to the dynamics of a fish farm; Methods: Samples were collected every other day, within a period of twenty consecutive days, during the dry and rainy seasons. Two samples were collected upstream from the fish pond (reservoir); the other four samples were collected in the fish farm area; Results: Rotifera and Chlorophyceae species were found in high densities at almost all sampling sites during both seasons under analysis. The higher phytoplankton species richness from site P3 to P6 was influenced by the management employed within the fish farm. The zooplankton community showed low values of density, species richness and equitability during the dry season; Conclusions: The continuous water flow and the addition of fertilizers (organic and inorganic) in the fish ponds had an influence on the plankton community, leading to a reduction in water quality and Cyanobacteria dominance.

Influence of the bipartite scrotum on the testicular and scrotal temperatures in goats

O objetivo deste trabalho foi avaliar a influência do grau de bipartição escrotal e do período do ano sobre a termorregulação escroto-testicular em caprinos criados no Estado do Piauí. Foram utilizados 18 reprodutores caprinos machos, divididos em três grupos de seis animais: O Grupo I contendo caprinos com escroto simples, o Grupo II, caprinos com escroto bipartido até 50% do comprimento testicular e o Grupo III, caprinos com bipartição superior a 50% do comprimento testicular. Os parâmetros avaliados foram as temperaturas do escroto, testículo e funículo espermático, obtidas de forma invasiva, com um termômetro digital termoacoplável, e não invasiva, com um pirômetro, nos terços proximal, médio e distal. Os dados foram coletados nos períodos seco (outubro-novembro) e chuvoso (fevereiro-março) do ano, bem como, nos turnos da manhã (6h00 às 7h00) e tarde (14h00 às 15h00). Os resultados foram submetidos à análise de variância (ANOVA) seguida do teste SNK para comparação das médias (p<0,05). O período do ano interferiu na termorregulação escroto-testicular, pois no período seco as temperaturas do escroto, testículo e funículo espermático foram mais elevadas que as observadas no período chuvoso. O grau de bipartição do escroto foi outro fator que modificou a temperatura escroto-testicular, já que os caprinos que apresentaram escroto com maior grau de bipartição demonstraram as menores médias das temperaturas escroto-testiculares em ambos os períodos e turnos avaliados. Conclui-se, portanto, que tanto o período do ano quanto o grau de bipartição do escroto influenciaram o processo de termorregulação escroto-testicular em caprinos.

Antimicrobial resistance of heterotrophic marine bacteria isolated from seawater and sands of recreational beaches with different organic pollution levels in southeastern Brazil: evidences of resistance dissemination

Antimicrobial resistance of marine heterotrophic bacteria to different antimicrobials agents were evaluated in seawater, dry and wet sands from three marine recreational beaches with different pollution levels. In all studied beaches, the greatest frequencies of resistance were found in relation to penicillin. on Gonzaguinha, the most polluted beach, 72.3% of all isolated strains showed simple resistance, whilst 8.33% had multiple resistance. The values found on Ilha Porchat beach, were 70.8% and 6.9% for simple and multiple resistances, respectively. on GuaraA(0), the less polluted beach, only 35.3% of isolated strains had simple resistance. Multiple resistance was not observed. While samples from Gonzaguinha and Ilha Porchat beach showed isolated strains resistant to seven and six different antimicrobial agents, respectively, samples from GuaraA(0) beach were resistant only to penicillin and erytromicin. The positive correlations obtained between the degree of seawater contamination and frequency and variability of bacterial resistance indicate that polluted marine recreational waters and sands are sources of resistant bacteria contributing thus, to the dissemination of bacterial resistance.