Rearing Water Research Articles

Mechanism for Preventing Fungal Infection with Halocrusticida okinawaensis in Larvae of Swimming Crab by Adjusting pH of Rearing Water to 9.25

Mechanism for Preventing Fungal Infection with Halocrusticida okinawaensis in Larvae of Swimming Crab by Adjusting pH of Rearing Water to 9.25

Dynamics of the Bacterial Cold-water Disease Pathogen, Flavobacterium psychrophilum, in Infected Fish Organs and Rearing Water after Warmed Water Treatment

Bacterial cold-water disease (BCWD) causes heavy mortality of ayu Plecoglossus altivelis in Japan. To control BCWD of ayu, warmed water treatment at 28°C has been used. However, the mechanism of this treatment is unknown. Hence, we investigated the growth/survival of Flavobacterium psychrophilum at 15-28°C under two nutritional conditions: in modified cytophaga (MCY) broth and sterilized underground water. Within 2 days at 28°C in both the conditions, F. psychrophilum totally lost its colony-forming ability. We also studied distributions of F. psychrophilum in infected fish organs and in rearing water after various treatments. For bacteria detection, the colony-counting method and loop-mediated isothermal amplification (LAMP) method were used. For warmed water treatment, the rearing water was warmed from 18°C to 23°C or 28°C for 3 days. The treatments were started 1 day after immersion infection. In the experimentally infected fish, F. psychrophilum was detected neither in any fish organs nor in the rearing water after the 28°C treatment for 3 days. These results indicate the effectiveness of the warmed water treatment at 28°C against BCWD of ayu.

Amoebae Isolated from Fish and Rearing Water at Oscar Astronotus ocellatus Farm

Amoebae Isolated from Fish and Rearing Water at Oscar Astronotus ocellatus Farm

Phylogenetic characterization of the heterotrophic bacterial communities inhabiting a marine recirculating aquaculture system

The aim of the present work was to characterize the heterotrophic bacterial community of a marine recirculating aquaculture system (RAS). An experimental RAS was sampled for the rearing water (RW) and inside the biofilter. Samples were analysed for bacterial abundances, community structure and composition by using a combination of culture-dependent and -independent techniques. The most represented species detected among biofilter clones was Pseudomonas stutzeri, while Ruegeria spp. and Roseobacter spp. were more abundant among isolates. In comparison, the genera Roseobacter and Ruegeria were well represented in both the biofilter and the RW samples. A variety of possible bacterial pathogens (e.g. Vibrio spp., Erwinia spp. and Coxiella spp.) were also identified in this study. Results revealed that the bacterial community in the RW was quite different to that associated with the biofilter. Moreover, data obtained suggest that the whole bacterial community can be involved in maintaining an effective and a stable rearing environment (shelter effect). Improving the reliability and the sustainability of RAS depends on the correct management of the bacterial populations inside it. This study furnishes more accurate information on the bacterial populations and better clarifies the existing relationships between the bacterial flora in the RW and that associated with the biofilter.

Effectiveness of Increasing Temperature of Rearing Water and Non-feeding against Viral Endothelial Cell Necrosis of Eel

Viral endothelial cell necrosis of eel (VECNE) of Japanese eel Anguilla japonica, caused by an adenovirus (JEAdV), has been a serious problem of aquaculture industry in Japan. In the present study, effectiveness of increasing water temperature and non-feeding against VECNE was evaluated. Cumulative mortalities of fish intraperitoneally injected with 105.05 TCID50/fish of JEAdV increased with elevating water temperature in the range between 20°C and 31°C, but mortality at 35°C was as low as that at 20°C. Rearing infected fish under the non-feeding condition further enhanced the effect of treatment at 35°C. The effectiveness was dependent on rearing periods at the high temperature; more than 3 days at 35°C were needed to reduce mortality. Fish, which survived the primary challenge with JEAdV at 35°C, showed high resistance to re-challenge with JEAdV. From these results, the treatment of fish under the non-feeding condition at 35°C is useful to control VECNE.

Identification of Bacterial Isolates with Antibacterial Activities in Intestinal Tracts and Rearing Water of Japanese Flounder Based on 16S rDNA Sequence Analysis

Identification of Bacterial Isolates with Antibacterial Activities in Intestinal Tracts and Rearing Water of Japanese Flounder Based on 16S rDNA Sequence Analysis

Microflora in the Rearing Water of Japanese Flounder(Paralichthys olivaceus) at the Larval Stage

Microflora in the Rearing Water of Japanese Flounder(Paralichthys olivaceus) at the Larval Stage

Effect of salt concentration in larval rearing water on susceptibility of Aedes Mosquitoes (Diptera: Culicidae) to eastern equine and Venezuelan equine encephalitis viruses.

The effect of salt concentration in larval rearing water on the susceptibility of adult Aedes taeniorhynchus (Wiedemann) and Aedes sollicitans (Skuse) to infection with eastern equine encephalomyelitis (EEE) virus was tested in the laboratory. Ae. sollicitans was more susceptible to infection (79%, n = 82) and viral dissemination (16%) with EEE virus than was Ae. taeniorhynchus (42%, n = 184) and (5%), respectively, when fed on a chick with a viremia of 10(7) +/- 0.1 plaque-forming units/ml; however, infection rates in adults were not affected by rearing in salt concentrations ranging from fresh water to brackish water containing 2.4% sea salts (1 part fresh water and 2 parts seawater). When fed on the same viremic 6-d-old chicken, all 48 Aedes albopictus (Skuse), reared in fresh water, became infected. Similarly, Venezuelan equine encephalitis viral infection or dissemination rates did not vary among Ae. taeniorhynchus adults that were reared in water containing 0, 1, or 2% sea salts.

Effects of Hyperoxic Rearing Water on Blood Hemoglobin and Hematocrit Levels of Rainbow Trout

Abstract Rainbow trout Oncorhynchus mykiss cultured under hatchery conditions were exposed to hyperoxia by injection of oxygen into the rearing water. In two separate studies of 67 and 73 d, mean hemoglobin of experimental fish reared at oxygen levels averaging 147–220% saturation was 7.8–8.7% lower than that of control fish reared at mean oxygen saturations of 66–74%. Mean hematocrit of experimental fish was also 3.1–5.7% lower than that of control fish. Fish reared in hyperoxic conditions did not differ in growth, survival, or behavior from control fish. Fish exposed to hyperoxia rapidly adjusted hemoglobin and hematocrit to levels similar to those of control fish after oxygen injection was stopped.

The Influences of Addition of Minerals to Rearing Water and Smoltification on Selected Blood Parameters of Juvenile Steelhead Trout, Salmo gairdneri Richardson

Experiments were conducted to determine the influences addition of minerals to rearing water had on selected blood parameters of juvenile steelhead trout, Salmo gairdneri Richardson. Fish that were maintained in water with low mineral concentrations exhibited significant increases in plasma \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{wasysym} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document}${\mathrm{NH}}_{4}^{+}$\end{document} and concomitant decreases in plasma Na+ concentrations. The alterations in the levels of these ions coincided with severe gill swelling and increased mortality. The changes in blood parameters, gill structure, and mortality probably are coincident with early changes associated with smoltification. Fish reared in water supplemented with minerals did not dis...

Effect of amiloride on sodium transport across body surfaces of freshwater animals.

Effect of amiloride on sodium transport across body surfaces of freshwater animals.

On the uptake of 65Zn and concentration factor of Zn in marine organisms. II. Changes in Zn and 65Zn concentration in rearing water.

It was previously reported that stable and radioactive zinc concentration in water changed during the tracer experiment for the uptake of zinc in marine organisms. In the present study, the cause of the change in zinc and zinc-65 concentration in water was investigated, and the followings were revealed: (1) zinc in dust contaminates the rearing water for tracer experiment, (2) the presence of organisms changes the zinc content in water, and (3) the reduction in zinc-65 concentration in water corresponds to the uptake amount by shellfish.