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41.
Akihiro Okamura Hideo P. Oka Noriyuki Horie Tomoko Utoh Yoshiaki Yamada Naomi Mikawa Satoru Tanaka Katsumi Tsukamoto 《Aquaculture International》2009,17(1):91-99
For efficient production of Japanese eel Anguilla japonica eggs, knowledge of the status of the sexual maturity of potential broodstock females is important because this status directly
influences the time required to produce mature eggs by successive hormone doses. Here we apply an eye index (relative eye
size) to evaluate the gonadal status of feminized A. japonica, which were induced by administration of estradiol-17β. Examination of gonad somatic and eye indexes of 267 feminized eels,
cultivated for 12–56 months, revealed a significant correlation between these two indexes. Artificial maturation of 35 feminized
eels showed that the number of hormone injections administered before ovulation was significantly lower as the eye index score
increased, indicating availability of this noninvasive method of predicting sexual maturity of feminized eel. There was no
correlation between eye index and fertilization rate, hatching rate, or larval survival rate, suggesting that sexual maturity
before hormonal treatment does not affect egg quality. 相似文献
42.
Fish‐processing wastes as an alternative diet for culturing the minute rotifer Proales similis de Beauchamp
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Robert Nesta Kagali Eric Ochieng Ogello Yoshitaka Sakakura Atsushi Hagiwara 《Aquaculture Research》2018,49(7):2477-2485
We evaluated the suitability of fish waste diet (FWD) for culturing the minute rotifer Proales similis through the observation of their population growth and particle size selective feeding. A total of five treatments either with Nannochloropsis oculata or FWD (0.75 and 0.50 g/L) or the combination of N. oculata and FWD were set up in triplicates. P. similis were cultured in diluted natural seawater (8 g/L salinity) and 26 ± 1°C with the diet treatments being applied randomly. We daily monitored the rotifer density, the number of bacteria and the water quality in all the cultures. The population density of P. similis increased exponentially in all treatments, while the mean growth in FWD 0.75 g/L was significantly higher (p < .05) than that in the control. Addition of N. oculata to FWD resulted to lowered P. similis population growth. Bacterial colony count was high in FWD and introduction of P. similis to the diet decreased their density. The estimated bacteria ingestion rates were generally in the range of 6.03 × 102–1.24 × 104 bacteria/rotifer/hr and there was a positive linear relationship between bacterivory and rotifer population growth. We also observed a shift in the particle size distribution with a reduction in the frequency and concentration of small‐sized particles (<2.5 μm) at day 6. These results accentuate the potential of fish‐processing waste as diet for culturing P. similis which feeds on bacteria and small particles (≤2.5 μm) that are by‐products of degradation of this diet. 相似文献
43.
Yoshitaka Oishi 《Biological conservation》2009,142(12):2854-2861
Drought-sensitive bryophytes are especially vulnerable to edge effects caused by forest fragmentation. Because of increased forest fragmentation, these bryophyte species are declining and are in need of conservation. Considering that a field survey including all bryophyte species is very time consuming, methods that make identification less difficult should be tested for their usefulness in conservation. This paper describes an alternative survey method that utilizes the correlation between bryophyte life-forms and microclimates for evaluating drought-sensitive bryophytes. This survey method was examined using epiphytic bryophyte flora on tree trunks in 27 fragmented forests of Kyoto city, in the western part of Japan. The usefulness of life-forms for this evaluation was discussed based on the correlation of life-forms with species richness and microclimates. The results indicated that, while life-from richness was considered to reflect the heterogeneity of moisture availability and light intensity in bryophyte habitats, a certain life-form category (for example, fans and dendroids) seemed to correlate with drought sensitivity of bryophytes. Considering this correlation, an alternative survey method was proposed that utilizes the richness of hygrophilous life-forms. This survey method seems to be more cost-effective than a traditional all-species survey, and provides an important step toward the conservation of drought-sensitive species. 相似文献
44.
This study focuses on spatial heterogeneity in the soil microbial biomass (SMB) of typical climax beech (Fagus crenata) at the stand scale in forest ecosystems of the cold-temperate mountain zones of Japan. Three beech-dominated sites were selected along an altitudinal gradient and grid sampling was used to collect soil samples at each site. The highest average SMB density was observed at the site 1500 m a.s.l. (44.9 gC m−2), the lowest was recorded at the site 700 m a.s.l. (18.9 gC m−2); the average SMB density at the 550 m site (36.5 gC m−2) was close to the overall median of all three sites. Geostatistics, which is specifically designed to take spatial autocorrelation into account, was then used to analyze the data collected. All sites generally exhibited stand-scale spatial autocorrelation at a lag distance of 10-18 m in addition to the small-scale spatial dependence noted at <3.5 m at the 550 m site. Correlation analysis with an emphasis on spatial dependency showed SMB to be significantly correlated with bulk density at the 550 and 1500 m sites, dissolved organic carbon (DOC) at the 700 and 1500 m sites, and nitrogen (N) at the 550 and 700 m sites. However, no soil parameter showed a significant correlation with SMB at every site, and some variables were also differently correlated (negative or positive) with SMB at different sites. This suggests that the factors controlling the spatial distribution of SMB are very complex and responsive to local in situ conditions. SMB regression models were generated from both the ordinary least-squares (OLS) and generalized least-squares (GLS) models. GLS performance was only superior to OLS when cross-variograms were accurately fitted. Geostatistics is preferable, however, since these techniques take the spatial non-stationarity of samples into account. In addition, the sampling numbers for given minimum detectable differences (MDDs) are provided for each site for future SMB monitoring. 相似文献
45.
Mohammad Ashik Iqbal Khan Kihachi Ueno Sakae Horimoto Fuminori Komai Kinji Tanaka Yoshitaka Ono 《Biology and Fertility of Soils》2009,45(3):305-313
The aims of this study were to monitor the changes in physicochemical, including spectroscopic, and biological characteristics
during composting of green tea waste–rice bran compost (GRC) and to define parameters suitable for evaluating the stability
of GRC. Compost pile temperature reflected the initiation and stabilization of the composting process. The pH, electrical
conductivity, NO3
−-N content, and carbon-to-nitrogen ratio were measured as chemical properties of the compost. The color (CIELAB variables),
humification index (the absorption ratio Q
4/6 = A
472 / A
664 of 0.5 M NaOH extracts), absorption at 665 nm of acetone extracts, and Fourier-transform infrared (FT-IR) spectra were measured
to evaluate the organic matter transformation; germination of komatsuna or tomato seeds was measured to assess the potential
phytotoxicity of composting materials during composting. No single parameter was capable of giving substantial information
on the composting process, the nutrient balance, phytotoxicity, and organic matter decomposition. The FT-IR spectra at 3,300,
2,930, 2,852, and 1,065 cm−1 provided information on the molecular transformation of GRC during composting and they decreased over the composting. Most
of the assayed parameters showed no further change after about 90 days of composting suggesting that GRC can be used for agricultural
purposes after this period. 相似文献
46.
Xin Zhao Yoshitaka Kakubari 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(4):322-332
Abstract Soil microbial biomass (Cmic) is an important factor regulating a number of ecosystem processes. In this study, we investigated seasonal variations in soil microbial biomass in natural climax beech (Fagus crenata) forests in a typical cold-temperate mountain region of Japan. Four permanent tower sites along an altitudinal gradient were selected and soil samples were collected once every month during the growing season of 2007. Soil microbial biomass (by fumigation-extraction method) and soil properties were later measured in the laboratory, while environmental factors (soil temperature, soil moisture) were continuously recorded in the field. Our results indicated large seasonal variations (130.4 ~ 5558.0 µg g?1) in soil microbial biomass in beech forests – a range that is much larger than previously reported. Statistically significant correlations are noted between soil properties with Cmic, but largely due to spatial linkages. On the other hand, the environmental factors of soil temperature and especially soil moisture largely control seasonal variations in Cmic. Furthermore, pH could be an important factor influencing seasonal change in Cmic at the 20–30 cm deep soil layer. The study suggests no direct correlation between plant eco-physiology and soil microbial biomass in seasonal courses of the forests. 相似文献
47.
Abstract The clay mineral composition of two “terra roxa estruturada” (TRE) soils occurring in the tropical rain forest and tropical forest/savannah transition zone, and a reddish brunizem in the savannah/semi-arid transition zone was studied comparatively in the southeast Amazon region. Kaolin minerals were dominant in these soils, and hematite and goethite were found in the clay fraction. A small amount of 2 : 1-type clay minerals was found in two soils. The mineral composition of the clay fraction in the TRE soils was hardly influenced by the difference of the meteorological factor or their water condition in this region, and this factor should not control the influence of parent materials derived from basic rocks. The TRE soils were developed under the condition of laterite genesis, and were regarded claymineralogically as a kind of the lateritic soils. 相似文献
48.
Keiki Okazaki Takuro Shinano Norikuni Oka Masako Takebe 《Soil Science and Plant Nutrition》2013,59(6):696-706
Among agricultural soil fertility management options, the environmental benefits of organic amendments have recently drawn particular attention. However, little information exists about their effects on crop metabolites or quality. Field plots of Komatsuna (Brassica rapa L. var. perviridis) were planted in a fractional factorial design with the following treatments: soil amendments of cattle manure (0, 2 or 4?kg?m?2), wheat straw (0, 0.05 or 0.1?kg?m?2), fast release nitrogen (N) (0, 6 or 12?g?N?m?2 of ammonium sulfate), slow release N (0, 3 or 6?g?N?m?2 of coated ammonium nitrate), phosphorus (P) [0, 5 or 10?g phosphorus pentoxide (P2O5)?m?2 of lime superphosphate] and potassium (K) [0, 6 and 12?g potassium oxide (K2O)?m?2 as potassium sulfate]. Metabolite profiling was carried out using a gas chromatograph/mass spectrometer (GC/MS), which yielded 62 and 67 metabolites in the leaves and the petioles, respectively. Metabolite peak areas were subjected to principal component analysis (PCA). The first component accounted for 44.1% of the total variance and bore a close relationship to N. The third component accounted for 8.8% of the total variance and was used to distinguish between different levels of manure application. An analysis of variance (ANOVA) of treatment factor effects on individual metabolites showed that the three most significant factors, from highest to lowest, were N absorption, manure amendments and slow release N. The effects of the manure amendments were not fully explained by its attendant N, P or K inputs. This result raises the question as to what mechanisms may bring about the metabolic changes caused by the manure amendment. The current findings will serve to direct further studies on the relationship between crop quality and cultivation procedures and will lead to more efficient quality control methods. 相似文献
49.
Yoshitaka Sakakura Shigeaki Shiotani Hisashi Chuda Atsushi Hagiwara 《Fisheries Science》2006,72(5):939-947
The water flow in larval rearing tanks has been indicated to cause mass mortality of the seven-band grouper Epinephelus septemfasciatus larvae. Therefore, a new aerating method was tested in an actual scale intensive rearing tank (8.0 m in diameter, 1.87 m
of water depth, 100 m3 of volume), in which an aerator was positioned at the center of the rearing tank surrounding cylindrical drain (1.2 m in
diameter) to generate the flow field, and seven larval rearing trials were performed. The survival rate with the former aeration
methods were compared, in which several aerators were located in the rearing tank. The survival rate at 10 days after hatching
with the new aeration method (61.5±5.1%, n=7) was approximately three times higher than the former methods (21.2±13.7%, n=6). The flow environment of rearing tanks was also examined by quantifying the flow field, and the relationship between the
flow field in the rearing tank, behavior of larvae and survival discussed. It was confirmed that the vertical circulating
flow was observed in rearing tanks, and determined effectively the survival and the behavior of grouper larvae in patchiness. 相似文献
50.
Effects of β‐carotene‐enriched dry carrots on β‐carotene status and colostral immunoglobulin in β‐carotene‐deficient Japanese Black cows
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Yoshitaka Nishijima Saya Taniguchi Shuntaro Ikeda Kenichi Yoshitani Takashi Hamano Hiroshi Tani Masahiko Fujita Kenji Murakami Keisuke Kogusa Kenji Sato Miki Sugimoto Shinichi Kume 《Animal Science Journal》2017,88(4):653-658
Data from 18 β‐carotene‐deficient Japanese Black cows were collected to clarify the effects of feeding β‐carotene‐enriched dry carrots on β‐carotene status and colostral immunoglobulin (Ig) in cows. Cows were assigned to control or carrot groups from 3 weeks before the expected calving date to parturition, and supplemental β‐carotene from dry carrots was 138 mg/day in the carrot group. Plasma β‐carotene concentrations in the control and carrot groups at parturition were 95 and 120 μg/dL, and feeding dry carrots slightly improved plasma β‐carotene at parturition. Feeding dry carrots increased colostral IgA concentrations in cows and tended to increase colostral IgG1, but colostral IgM, IgG2, β‐carotene and vitamin A were not affected by the treatment. Feeding dry carrots had no effects on plasma IgG1, IgA and IgM concentrations in cows, but plasma IgG1 concentrations decreased rapidly from 3 weeks before the expected calving date to parturition. These results indicate that feeding β‐carotene‐enriched dry carrots is effective to enhance colostral IgA and IgG1 concentrations in β‐carotene‐deficient cows. 相似文献