Survival Rates In Water Research Articles

Effect of artificial seawater and feeding frequency on the larval culture of freshwater Amazonian ornamental fish banded cichlid Heros severus (Heckel, 1840) and angelfish Pterophyllum scalare (Schultze, 1823)

The present study aimed to evaluate the effect of salinity and feeding frequency on zootechnical performance of Pterophyllum scalare and Heros severus five-day-old post-larvae. Two experiments were performed in a completely randomized experimental design in a 5 × 2 factorial scheme, with 5 different NaCl concentrations (0, 2, 4, 6 and 8 g/L) and 2 feeding frequencies (2 and 4 times a day). P. scalare showed the highest survival rates (p<0.05) when subjected to salinities of 0, 2 and 4 g/L (97.50–96.25%), and higher values (p<0.05) for standard length (13.22 mm), weight (64.64 mg) and specific growth rate (15.41% per day) when fed 4 times a day. For this species, feeding frequency did not influence survival rates. H. severus, in turn, showed higher survival rates in water without the addition of salt (96.25%) and the highest standard length in salinity of 2 g/L (11.80 mm). H. severus fed 4 times a day and presented the highest values (p<0.05) for most of the growth variables (weight: 57.28 mg, specific growth rate: 18.30% per day). The results of the present study suggest that banded cichlid post-larvae showed higher survival rates in water without salt addition, however, the best growth of this species occurred at the salinity of 2 g/L. In contrast, angelfish post-larvae can be cultivated in salinities of up to 4 g/LNaCl. A feeding frequency of 4 times per day is recommended for both species.

Pressure tolerance of Artemia cysts compressed in water medium

ABSTRACTThe high pressure tolerance of cysts of Artemia salina was investigated up to several GPa in water. No survival was observed after exposure to 1.0 GPa for 15 min. After exposure to 2.0 GPa for the same time duration, the hatching rate had recovered to 33%, but decreased to 8% following compression at 7.5 GPa. This contrasts with results using Fluorinert™ as the pressure-transmitting medium where 80–88% recovery was observed. The lower survival rate in water is accompanied by swelling of the eggs, indicating that liquid H2O close to the ice-VI crystallization pressure penetrated inside the eggs. This pressure exceeds the stability limit for proteins and other key biomolecules components within the embryos that could not be resuscitated. Rehydration takes several minutes and so was not completed for all samples compressed to higher pressures, prior to ice-VI formation, resulting in renewed survival. However H2O penetration inside the shell resulted in increased mortality.

The effect of different kinds of electrolyte and non‐electrolyte solutions on the survival rate and morphology of zebrafish Danio rerio embryos

The effect of electrolyte and non-electrolyte solutions on the survival and on the morphology of zebrafish Danio rerio embryos was investigated. Embryos in different ontogenetic stages were incubated in electrolyte (NaCl, KCl, MgCl2 and CaCl2) and non-electrolyte solutions [sucrose and polyvinylalcohol (PVA)] of different concentrations for 5-15 min. The embryos were hatched to the long-pec stage and the effective concentrations which caused a 50% decrease in embryo development (EC50) were determined. The morphometric changes, which were caused by the test solutions, were measured. Ion channel blockers were used to see if active ion transport played a role for embryo survival. Finally, dechorionated embryos were exposed to the test solutions to get indications about the importance of chorion and perivitelline space. For 12 hours post fertilization (hpf) embryos and a 15 min exposure period, EC50 was highest for MgCl2 (1.60 mol l(-1)), followed by sucrose (0.73 mol l(-1)), NaCl (0.49 mol l(-1)), KCl (0.44 mol l(-1)), CaCl2 (0.43 mol l(-1)) and PVA [0.0005 mol l(-1) (2.2%)]. EC50 were lower for early embryonic stages than for advanced stages for all solutions with exception of MgCl2 and sucrose. At the EC50, MgCl2 and CaCl2 solutions did not induce morphometric changes. NaCl and sucrose solutions induced reversible morphometric changes, which were compensated within 10 min. Only the EC50 of KCl and PVA solutions induced permanent morphometric changes, which could not be compensated. Incubation of embryos in electrolyte and non-electrolyte solutions together with ouabain (blocker of Na+- K+ ATPase), HgCl3 (dose-dependent inhibition of aquaporine channels), verapamil (inhibition of calcium and magnesium uptake) and amiloride (inhibition of sodium uptake) significantly decreased the per cent of embryos developing to the long-pec stage in comparison to the same solutions without blockers. Ouabain and HgCl(3) also induced morphometric changes. For dechorionated embryos the survival rates in water and in the different test solutions were similar to untreated embryos.

Factors affecting chilled storage of zebrafish ( Danio rerio) embryos

Chilled storage of zebrafish embryos was investigated at a temperature that arrests embryonic development as this technique might offer interesting practical applications. Five parameters played an important role for chilled storage: (a) storage temperature, (b) development stage of embryos, (c) storage solution (extender), (d) postchilling treatment, and (e) inhibition of growth of microorganisms by antibiotics. The optimal chilling temperature was 8 °C. Prim-5 stage (24 h postfertilization [hpf]) and prim-25 stage (36 hpf) embryos had similar high chilling resistance and could be chilled for 33 h without a loss in viability. Five-somite stage (12 hpf) embryos had a lower chilling resistance and could be chilled only for 14 h without a loss in viability. After longer incubation periods, the viability started to decrease. Under these conditions, chilling in physiologic saline solutions was superior to that in water. Fifty percent of the prim-5 stage and prim-25 stage embryos survived for 41 h at 8 °C in water but for 46 h in physiologic saline solution. A similar effect was observed for 5-somite stage embryos (50% survival rate in water, 28 h; 50% survival rate in physiologic saline solution, 35 h). When embryos were incubated in physiologic saline solution instead of water in the postchilling phase, the embryo viability was positively affected, too. Also, supplementation of the storage solution with antibiotics (penicillin and streptomycin) increased the viability of chilled embryos. In summary, the current study shows that chilled storage of zebrafish embryos is possible for sufficiently long periods to synchronize the development of embryos deriving from different spawning dates or to delay the development for experimental purposes. To prolong the storage periods, further development and standardization of the methodology is necessary.

Migratory behaviour and desiccation tolerance of protostrongylid nematode first-stage larvae

Migration of first-stage larvae (L1) from faeces to soil is a crucial stage in the life-history of protostrongylids transmitted via land snails. Migration of Muellerius cf. capillaris and a Cystocaulus sp. L1 from fresh Nubian ibex ( Capra ibex nubiana) faeces (48–50% water content, W.C.) to substrate soils (at 100% r.h., 26°C) was measured experimentally using dry (3 ± 1% W.C.), wet (31 ± 0.43% W.C.) and flooded (48.4 ± 2.45% W.C.) soils. The highest migration rates (90.4 ± 1.6% migration) in both species occurred on flooded soils when the faecal pellet W.C. reached 90%. The next highest migration rates (43.2 ± 3.6% migration, at 60% faecal W.C.) were on the wet soils and no migration occurred on dry soil or dry-substrate papers. Migration rates did not differ significantly ( P > 0.05) between species. Active Theba pisana were not infected by M. cf. capillaris L1 on dry infested soils, but were infected following rehydration of the same soils. By day 10, L1 of M. cf. capillaris demonstrated lower survival rates in water and in 97% and 76% r.h. (74.5%, 15.2% and 1.9%, respectively) than the Cystocaulus sp. (97.5%, 43.8%, 43.3%) and Protostrongylus sp. (97.9%, 43.2%, 23.8%, P < 0.05). All three nematodes had a remarkably high survival rate (> 99% overall survival, by day 10) when exposed directly to 0% r.h. at 23°C, Results demonstrate the ability of L1 to survive extreme desiccation through anhydrobiosis. Migration of L1 from facces to soil can take place only during rains which coincide, with peak activity of land snails in desert habitat.

Effect of Ozonation on Microbial Fish Pathogens, Ammonia, Nitrate, Nitrite, and BOD in Simulated Reuse Hatchery Water

The effectiveness of ozone as a disinfectant of makeup water and its potential for treatment of recycled water in commercial reuse hatcheries was considered in this study. Comparative survival rates in water were established for four bacterial fish pathogens (Aeromonas salmonicida, A. liquefaciens, Pseudomonas fluorescens, Yersinia ruckeri [the causative agent of enteric redmouth disease]), Bacillus polymyxa, and a bacterium–protozoan population during batch and continuous flow ozonation. A specific microbial ozone demand was exerted during batch ozonation, and &gt; 99% mortality of the fish pathogens was observed within 60-s contact during continuous flow exposure at 1.0 and 0.1 mg O3/L. Spores of B. polymyxa were resistant to a concentration of 1.0 mg O3/L for at least 10 min. The oxidation rate for the combined bacterial–protozoan biomass closely approximated rates established in pure culture studies, with no significant difference in relative survival rates between bacteria and protozoa. Elevated carbon levels did not appear to exert a preferential ozone demand when added to suspensions of test organisms. Oxidation of carbon and nitrite by ozone was rapid at low ozone concentrations, with carbon and ammonia oxidation rates exhibiting pH-dependence. The oxidation capacity of ozone in water was greatest at elevated pH even though the measurable ozone concentration was lower. Key words: ozone, fish pathogens, BOD, nitrite, ammonia, protozoans