Control of dissolved oxygen levels of water in net pens for fish farming by a microscopic bubble generating system

ABSTRACT:   A microscopic bubble generating system (MBGS) has been developed to control dissolved oxygen (DO) levels suitable for fish farming. The MBGS has been tested to confirm its capability in net pens. Water conditions in a fish farm were monitored every two hours from June to October 2004 by setting an online vertical profiling system (OVPS) close to the net pen. DO in the net pen water decreased to physiologically stressful levels for the fish during the night (4.84–5.51 mg/L), while the DO was kept in saturated conditions during the day, due to oxygen supply from phytoplankton. The MBGS was operated from the evening to the morning of the next day for 16 h, to successfully create DO-saturated conditions in the net pen water at night. By using microscopic bubbles during the warm seasons, DO levels in the net pen water could be improved to a level suitable for fish farming. However, the low DO levels (<5.0 mg/L) of the bottom water occasionally extended to the net pen layers, despite the supply of microscopic bubbles to the water. To maintain the DO of the net pen water at levels suitable for fish farming, DO supply to the net pen water and the bottom water needs to be increased, and the organically enriched sediment just below the net pens needs to be treated.     

Seasonal fluctuations in the flux of particulate organic matter discharged from net pens for fish farming

ABSTRACT:   Fish farming using net pens consumes large amounts of food for the reared fish, resulting in organic enrichment of the sediment below the fish farm from organic discharge in the forms of fish feces and food residues. Sediment traps were set at a net pen within and outside a fish farm, and organic flux on the sea floor was compared. The year-mean organic flux to the sea floor caused by fish farming from September 2003 to September 2004 was estimated at 2.11 gC/m²/day in total organic carbon (TOC) and 0.26 gN/m²/day in total nitrogen (TN), which were 2.5 times (TOC flux) and 2.2 times (TN flux) larger than that for natural organic flux outside the fish farm. The seasonal fluctuation patterns of organic flux to the sea floor below the fish farm did not necessarily coincide with those for the amount of food spent for the fish farming. The largest organic flux to the sea floor occurred in the autumn, when the vertical mixing of the water had just started. Therefore, organic enrichment of the sediment on the sea floor of a fish farm proceeded during this season.     

Highly efficient induction of triploid Pacific abalone <Emphasis Type="Italic">Haliotis discus hannai</Emphasis> by caffeine treatment

ABSTRACT:   In order to develop a highly efficient method for mass production of triploid Pacific abalone Haliotis discus hannai , caffeine treatment that is safe and inexpensive was optimized. To suppress the first meiotic division, fertilized eggs were exposed to either a 10- or 15-mM caffeine solution for 24 min beginning at 12 min after fertilization. In most treated batches, the rates of cleaved eggs showed no significant difference from the control batches. However, in most treated batches, the rates of occurrence of normal larvae and the survival rates of the early juveniles were significantly lower than those of the controls. The triploid rates at 6 days to 11 months after settlement in all the treated batches were extremely high (91–100%). There was no significant difference in the mean triploid rates between 10- and 15-mM caffeine treatments. These results suggest that both treatment conditions were conducive to triploid abalone production. One live 2n/3n mosaic specimen was found in the treated batches. However, since the frequency of mosaic was extremely low, the mosaicism would probably not have an adverse effect on the stable production of triploid abalones.     

Structural identification of anthocyanins and analysis of concentrations during growth and flowering in buckwheat (Fagopyrum esculentum Moench) petals

The anthocyanin profiles and variety/breeding-line differences of anthocyanin concentrations in petals of common buckwheat flowers have been studied. Four anthocyanins, cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, cyanidin 3-O-rhamnoside, and cyanidin 3-O-galactosyl-rhamnoside were isolated from the petals of common buckwheat (Fagopyrum esculentum Moench), separated using high performance liquid chromatography and identified using reversed-phase liquid chromatography-electrospray ionization-tandem mass spectrometry techniques. In every variety/breeding line tested, cyanidin 3-O-rutinoside was detected as the major anthocyanin and the next is cyanidin 3-O-glucoside whereas cyanidin 3-O-rhamnoside and cyanidin 3-O-galactosyl-rhamnoside were trace or not detectable in white and pink flowered buckwheat. Of all the varieties/breeding lines tested, Gan-Chao, a Chinese variety, contained the highest amount of anthocyanins. The largest part of cyanidin moiety was presented as a proanthocyanidin form (PAs-Cy). Anthocyanins and PAs-Cy in petals were increased along with increase of flower development stages. Therefore, fully developed petals of red flowered buckwheat, especially Gan-Chao, are promising as a new anthocyanin-rich material for food processing.     

Analysis of phloem exudate collected from fruit-bearing stems of coconut palm: Palm trees as a source of molecules circulating in sieve tubes

Sieve tubes have been attracting widespread research interest because of their possible role in mediating physiological signals within the whole plant. However, progress in research into the function of sieve tubes has been limited by the low volume of sap available. To overcome this problem, we attempted to collect phloem exudate from tropical coconut palm trees (Cocos nucifera L. cv. Namhom). As much as 3 to 15 mL of exudate per hour was collected from the cut surface of the plant's fruit-bearing stem. Our analyses revealed that the characterized profiles of sugars (sucrose: 339 mM), amino acids (total concentration: 17.1 mM), cations (potassium: 48.3 mM), and proteins (total concentration: 0.1 /-lg /-lL-1) in the exudate were mostly consistent with those of phloem sap or phloem exudate collected from rice plants, castor bean plants, etc. This exudate was assumed to reflect the composition of the phloem sap from the source organs of coconut palm trees. The large volume of exudate collected contributed significantly to the analyses of the various compounds in the stream of sieve tubes.     

Successful introduction of modified dorsolumbar epidural anesthesia in a bovine referral center

This study describes the successful use of modified dorsolumbar epidural anesthesia with a fixed volume of anesthetic in a bovine referral center. Among the 130 Holstein cattle scheduled for flank surgery, 90 cattle received a mixed anesthetic consisting of 1 ml of xylazine hydrochloride and 3 ml of lidocaine hydrochloride by modified dorsolumbar epidural anesthesia. Eighteen cattle with dehydration and/or lameness received a mixed anesthetic containing 0.5 ml of xylazine and 3 ml of lidocaine. Infiltration anesthesia was performed in 22 cattle whose epidural space could not be reached in order to perform the flank surgery. The surgeries began about 12 min after the administration of the anesthetic and lasted for about 36 min. The modified method using a fixed volume of anesthetic was successfully introduced and effectively used in a bovine referral center. This modified method will allow veterinarians to save time and effort, thus lowering the cost of each surgery.     

Digestive enzyme activities of pancreas and intestinal digesta in streptozotocin-induced diabetic piglets

Six (Landrace × Large White) × Duroc crossbred, castrated weanling piglets were used to evaluate the effect of a streptozotocin (STZ) injection to induce diabetes on the activities of digestive enzymes derived from the pancreas (lipase, amylase, trypsin and chymotrypsin) in the pancreas and intestinal digesta. Fasting plasma glucose after the administration of STZ was maintained at the level of 302–491 mg/dL during this experiment, compared with the level of 89–125 mg/dL in the control group, and they were defined as the STZ‐induced diabetic piglets for about 7 weeks. Although their bodyweight increased in proportion to a quadratic curve (P < 0.0001) during 49 days after the administration of STZ, the growth of the STZ‐induced diabetic piglets was slower compared with the control. The STZ‐injection did not affect the percentage of the pancreas in bodyweight. The administration of STZ in the piglets tended to accelerate the activity of lipase (P = 0.06) and depress the activity of amylase (P = 0.15) or chymotrypsin (P = 0.18), as units/kg bodyweight, in the pancreas. In the case of measurement as units/kg bodyweight, the activities of intestinal digesta in the STZ group showed a tendency to be higher than those in control group, irrespective of the sort of enzymes. In conclusion, STZ‐induced diabetic piglets have a moderate digestive ability and the administration of exogenous digestive enzymes is not necessary when they are used as a diabetic animal model.     

Antimicrobial susceptibility of Staphylococcus intermedius isolated from healthy and diseased dogs

A total of 90 strains of Staphylococcus intermedius isolated from dogs were examined for antimicrobial susceptibility. There were no significant differences in the distribution patterns of MICs between strains from 1982 to 1985 and those from 1999, and between strains from healthy dogs and those from diseased dogs. All of the strains were susceptible to ABPC, DMPPC, CEX, TDM, ERFX, BFLX, and FF at concentrations of 0.05 to 6.25 microg/ml. The MICs of OTC, KM, EM, AIV-TS, and LCM were distributed in a broad range of 0.1 to >100 microg/ml, indicating the existence of resistant as well as susceptible populations of S. intermedius. Thirty-three strains (36.7%) were resistant to one or more anitmicrobial agents such as OTC (n=32), KM (n=9), EM (n=7), AIV-TS (n=7), and LCM (n=7).     

Incident rainfall partitioning and canopy interception modeling for an abandoned Japanese cypress stand

Interception loss (E _i) in forests has been studied widely. However, E _i parameters and modeling as well as spatial patterns of throughfall (TF) in abandoned Japanese cypress (Chamaecyparis obtusa) plantations remain poorly documented. In this study, gross precipitation (P _G), stemflow (SF), and TF were monitored in an unmanaged 32-year-old Japanese cypress stand throughout the 2011 rainy season. Results indicate that P _G partitioning into TF, SF, and E _i were, respectively, 64.2 ± 3.6, 10.6 ± 0.6, and 25.2 ± 1.1 % of the 880.8 mm cumulative P _G from 29 rainfall events. Direct throughfall proportion (p) and drainage from the canopy contributed about 14 ± 7 and 50 ± 21 % of the total TF for the events, respectively. The mean canopy storage capacity (S) was 2.4 ± 0.7 mm. The coefficient of variability (CV) of TF rate decreased asymptotically with increasing P _G amount, ranging from 16 to 56 % with median 26 %. The CV of TF rate was not significantly correlated with canopy cover (r = 0.152, P = 0.521, n = 20) and distance from the nearest trunk (r = 0.196, P = 0.408, n = 20). Based on the revised Gash analytical model, the total simulated E _i was close to the observed, with a general underestimation magnitude of 5.7 %. The E _i components were quantified, and most of the interception loss (62.9 %) evaporated during rainfall, while 26.8 % evaporated after rainfall ceased. Climatic and forest structural parameters required by the model were identified and analyzed by sensitivity analysis, implying that the revised Gash analytical model is robust and reliable enough for abandoned Japanese cypress plantations in a maritime climate.