To study the effect of cellulolytic gut bacteria as a feed supplement on growth performance and nutrient digestibility of Asian seabass (Lates calcarifer), a 42 days experiment was done. Group I was fed on control diet (diet A), Group II, III and IV were fed with diet B (Bacillus subtilis), C (Bacillus licheniformis), and D (B. subtilis and B. licheniformis in 1:1 ratio) respectively. Higher (P<0.05) weight gain percent (248.75 %), specific growth rate (4.80) and apparent fiber digestibility were observed in group IV. Maximum (P<0.05) survivability (86.67 %), PER and apparent protein digestibility were significantly (P<0.05) higher and FCR (1.24) was significantly (P<0.05) lower in animals of group III. Total microbial population and cellulolytic bacterial population in the gut of juvenile seabass of group IV was significantly (P<0.05) higher than other groups. Amylolytic bacterial population was in the same range of group III and IV but they were significantly (P<0.05) higher than other two groups. Digestive cellulase enzyme activity was significantly (P<0.05) higher in group IV, digestive amylase and protease was in the same range of group III and IV. So, these two cellulolytic gut bacteria B. licheniformis and B. subtilis showed beneficial effect on seabass as feed supplement.

The alterations caused during water recirculation are little known in Brazil, especially in relation to the dynamics of the water and phytoplankton in a cultivation setting. The aim of the present study was to characterize the quality of the water and phytoplankton on shrimp farms raising Litopenaeus vannamei in northeastern Brazil that use either partial or total recirculation systems. Collections were performed in the supply, distribution and drainage channels at both low and high tides. Analysis of variance, followed by Tukey’s test, was used for the statistical analysis, with the level of significance was set at P < 0.05. On the farm with partial water recirculation, the response variables total ammonium (1.81 ± 0.78 mg.L-1), nitrite (0.10 ± 0.03 mg.L-1), phosphate (2.12 ± 0.5 mg.L-1), Bacillariophyta (520.625 ± 159.983 cells.mL-1), Chlorophyta (936.250 ± 416,309 cells.mL-1) and Pirrophyta (10.078 ± 2.762 cells.mL-1) were higher in the drainage channel. On the farm with total water recirculation, total ammonium (1.59 ± 0.01 mg.L-1) and Pirrophyta (27.046 ± 435 cells.mL-1) were higher in the drainage channel. The water recirculation systems (partial and total) achieved satisfactory levels for the cultivation of Litopenaeus vannamei.

Synodontis nigrita is an important indigenous species with aquaculture potential. However, this is yet to be achieved due to scanty information on its nutrient requirements. This study investigated the effects of different dietary crude protein levels on growth performance and haematological parameters of S. nigrita. Six hundred S. nigrita (mean weight 10.14 ± 0.04g) were stocked at 50 fish per treatment in four treatments and replicated thrice in concrete tanks. Fish were fed varying levels of experimental diets: 30%, 35%, 40% and 45% crude protein levels. Growth parameters such as weight gain (WG), specific growth rate (SGR), food conversion ratio (FCR) and protein efficiency ratio (PER) and haematological parameters of the fish samples: haemoglobin concentration (HB), packed cell volume (PCV), red blood cell count (RBC) and white blood cell count (WBC) were determined after the feeding trial. The data were analyzed using Statistical Package for Social Scientist (SPSS), Version 11, 2001 and Statistical Analysis Software (SAS), Version 8, 2001. Duncan’s multiple rage test was used to compare the differences among means. . The WG of fish fed 40% and 45% protein levels (5.73±0.06g and 6.37 ± 0.13g) were significantly higher (p<0.05) than those fed 30% and 35% protein levels. The SGR of 40% (0.54) and 45% (0.59) protein levels were significantly higher (p<0.05) than fish fed 30% and 35% protein levels. The FCR of fish fed 45% protein level was lower (10.84) compared to other fish fed 30%, 35% and 40% protein levels. The PER of fish fed 30%,35%,40% and 45% protein levels were not significantly different. Haematological data of fish fed 40% and 45% protein levels, Hb(7.06±0.18 and 7.84±0.59g/dl) and RBC(2.68±0.28 and 2.93±0.04106/mm3) were significantly higher (p<0.05) than in fish fed 30% and 35% protein levels. S. nigrita requires high dietary protein level for its successful aquaculture.

The present study was undertaken to investigate the acute toxicity of cadmium, a heavy metal widely detected in the aquatic environment due to natural effects and anthropogenic activities, in freshwater teleost, Channa punctata (Bloch). The experiments for the bioassay were performed in semi-static test condition according to the standard guidelines. The behavioural changes in the fish were observed for all tested concentrations of the metal. The data obtained for bioassay were analyzed for median lethal concentrations (LC50) of the metal by SPSS computer software, Finney’s Probit analysis and Trimmed Spearman-Karber’s method. The LC50 values, estimated by SPSS, with 95% confidence level were found to be: 26.88 (21.69-71.68), 18.76 (17.13-20.81), 16.70 (14.77-17.96) and 14.95 (13.13-15.88) mg l-1 for dissolved metal concentrations, at 24, 48, 72 and 96 h exposure durations respectively. All three methods showed good agreement among the estimates. Furthermore, the exposed specimens showed dose and duration dependent abnormal behaviour and hyperactivity.

A numerical model analysis was performed to analyze the motion of a Korean designed automatic submersible fish cage system in waves and currents. The fish cage system consisted of a 12-angle rigid frame, net cage, cover net, 12 upper floats, 12 tanks (for fixed and variable ballast), mooring ropes, anchors, and control station. Simulations were performed with the cage at the surface of the water and at a depth of 20 m. Using a Morison equation type model, simulations of the system were conducted on the two configurations. The force parameters described both regular and random waves, with and without currents, and their values were considered as input to the model. Heave, surge and pitch dynamic calculations were made. Results were analyzed in both the time and frequency domains and where appropriate, linear transfer functions were calculated.

This study aims to analyze the spatial and temporal distribution of the mollusc, Anomalocardia brasiliana along the Mangue Seco beach (Igarassu, PE, Brazil). The 1,800 meters beach line was divided into three sections (S) of 600 meters each; S1: 0 to 600, S2: 600 to 1200m and S3: 1200 to 1800m. Totally, 540 samples were taken at different levels, sections and during different seasons. A total of 1,016 specimen were collected during the two periods; January (summer) and August (winter) 2009. In January, 636 clams were collected of which 55% were smaller than 15 mm. In winter 380 samples were collected, 57% being of adult size, between 21 and 25 mm in length. The maximum density recorded in the summer period was 414.91 ± 82.48 ind.m-² at S3 and 323.49 ± 90.11 ind.m-² at S1respectively, which were significantly different from S2 (156.12 ± 28.72 ind.m-²). The lowest density was found during the winter with 102.67 ± 5.07 ind.m-² and 122.37 ± 36.86 ind m-² for S1 and S2 respectively, which largely differed from S3 (296.76 ind.m-² ± 45.20). Among the stations, S3 obtained the highest rate of biomass with 1,248.47 ± 305.82 g.m-² during the summer and 1,136 ± 191.14 g.m-² during the winter, which was significantly different from two other stations' sections. The rain exerts an influence on the distribution of the bivalve A. brasiliana, which was shown through the decreasing of the molluscs’ density, however, they also increased in size (>20mm) due to increase of food availablity in the rainy season.

The calanoid copepod Boeckella poopoensis (Marsh, 1906) is a widespread species inhabiting South American inland saline waters with gradient of salinity between 5-90 g/dm3 and it can be practically considered as obligate component of zooplankton of saline lakes. The aim of the present study is to analyze and compare morphometrically two populations of this species collected during two seasons in two small saline ponds with different salinity levels, located in northern Chile. The results of PCA revealed that the salinity would be weakly inversely associated with morphometric parameters, whereas many morphometric parameters are significantly directly associated. The results revealed that the salinity would not generate significant morphometric alterations in adults of B. poopoensis.

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