Aquaculture Science
Online ISSN : 2185-0194
Print ISSN : 0371-4217
ISSN-L : 0371-4217
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Volume 66, Issue 4
Displaying 1-11 of 11 articles from this issue
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Original paper
  • Species-identification of eggs of three flounders by whole-mount immunostaining
    Jun Nagata, Kei Kasai, Kazuhiro Mineno, Yudai Fujisaki, Yuji Mushirobi ...
    2018 Volume 66 Issue 4 Pages 257-266
    Published: 2018
    Released on J-STAGE: December 20, 2019
    DOIhttps://doi.org/10.11233/aquaculturesci.66.257
    JOURNAL FREE ACCESS
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    Whole-mount immunostaining (WI) was used for identification of eggs of brown sole (Pseudopleuronectes herzensteini), sand flounder (Limanda punctatissima) and pointhead flounder (Cleisthenes pinetorum). Polyclonal antibodies were raised in rabbit against vitelline envelope (VE) of ovulated eggs of each flounder (a-brown sole VE, a-sand flounder VE and a-pointhead flounder VE). A WI method was first developed using the non-labeled primary a-VE antibodies in conjunction with a labeled-secondary antibody (2-step method). Another WI method using the labeled-primary a-VE anitbodies alone was developed (1-step method) in order to omit the use of the secondary antibody. When fertilized eggs of each species (2-24 hrs post-fertilization) were examined, both WI methods effectively stained the eggs in a species-specific manner. Immunological tools developed for identification of flounder eggs in this study will contribute to simplify fishery surveys of flounder species during their early life stages.
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  • Assessment of ichthyofauna at oyster rafts in Hiroshima Bay, Japan, using underwater video cameras
    Atsushi Tsuyuki, Tetsuya Umino
    2018 Volume 66 Issue 4 Pages 267-274
    Published: 2018
    Released on J-STAGE: December 20, 2019
    DOIhttps://doi.org/10.11233/aquaculturesci.66.267
    JOURNAL FREE ACCESS
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    There is little information on fish communities around oyster farms, though oyster rafts provide habitats for fish and are important fishing grounds. We investigated the ichthyofauna at oyster rafts supporting Crassostrea gigas in Hiroshima Bay, using underwater video cameras. The fish species composition around the rafts was unique, consisting of identified 18 species, with low similarities to the fish community in nearby littoral areas. Several commercially important fishes, including black sea bream Acanthopagrus schlegelii, filefish Thamnaconus modestus, and surfperch Ditrema temmincki, aggregated at the oyster rafts throughout the year. The abundance of A. schlegelii (68%-85% relative abundance) accounting for most of the fish at the rafts, except in summer. The video recordings revealed that A. schlegelii, T. modestus, and D. temmincki preyed on the sessile organisms (probably mollusks, crustaceans and macroalgae) which had abundantly attached to the oyster wires. Thus, the large and persistent aggregations of fishes suggests that the oyster rafts efficiently function as an artificial reef in the regional ecosystem.
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  • Effect of vitamin B12 on resilience to turbidity stress for Moina macrocopa
    Nadia Istiqomah, Novi Arisman, Takao Yoshimatsu
    2018 Volume 66 Issue 4 Pages 275-285
    Published: 2018
    Released on J-STAGE: December 20, 2019
    DOIhttps://doi.org/10.11233/aquaculturesci.66.275
    JOURNAL FREE ACCESS
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    Sediment transport associated with extreme rainfall has become an important issue for aquatic animals under conditions of ongoing climate change. In this study, effect of vitamin B12, which is exclusively produced by bacteria in nature, were investigated for maintaining zooplankton fitness in changing environment. A series of experiments were conducted to explore possible damages caused by turbidity change and mitigation by vitamin B12 on the fitness of Moina macrocopa. Test animals were exposed during their entire lifespan with different levels of turbidity (0, 15, 50, 100, and 600 NTU by adding kaolin clay) and fed by Chlorella vulgaris with various levels of supplemental vitamin B12 (0, 5, 25 µg/l) and a commercial product which contained vitamin B12 in the cell. M. macrocopa showed better performance when fed on Chlorella with vitamin B12 compare to Chlorella without vitamin B12 upon exposure to turbidity change. The absence of vitamin B12 together with turbidity change exposure decreased lifespan, delayed the age of first reproduction, and decreased offspring number and size (P < 0.05). These results revealed that the resilience of M. macrocopa to turbidity change can be enhanced by the help of vitamin B12 in media and/or foods.
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  • Formation of scale ridges in the goldfish Carassius auratus exposed to calcium- and phosphorus-deficient conditions
    Masaharu Iguchi
    2018 Volume 66 Issue 4 Pages 287-296
    Published: 2018
    Released on J-STAGE: December 20, 2019
    DOIhttps://doi.org/10.11233/aquaculturesci.66.287
    JOURNAL FREE ACCESS
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    The role of calcification in the formation of ridges on the scales of goldfish was investigated. Goldfish were held in distilled water and fed a test diet deficient in calcium (Ca) and phosphorus (P) for 5 weeks. The anterior margin of scales from these fish were observed using a light microscope. After 2 weeks, the calcification was observed and compared with controls using scanning and transmission electron microscopy. In control fish, newly formed scale ridges were well calcified and had relatively sharp denticles. In fish fed the test diet, scale ridges formed but were uncalcified and had a mesh-like structure of collagen fibrils. Radial clusters of minerals were observed at the scale ridges in control fish, whereas only granular crystals were observed at the ridges in fish fed the test diet. These results suggest that scale ridges are mainly formed by collagen fibrils and not by the deposition of Ca and P. Scale growth was reduced in goldfish under Ca- and P-deficient conditions for 5 weeks. The number of ridges and the distance between ridges was also less in these fish. The changes in scale growth seemed to be synchronized with the formation of an organic matrix of collagen fibrils.
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  • Top-down effect in rice-fish culture using juvenile crucian carp evaluated by biota in experimental paddy fields
    Tetsuya Tsuruta, Kei’ichiro Iguchi
    2018 Volume 66 Issue 4 Pages 297-307
    Published: 2018
    Released on J-STAGE: December 20, 2019
    DOIhttps://doi.org/10.11233/aquaculturesci.66.297
    JOURNAL FREE ACCESS
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    Rice-fish culture using juvenile crucian carp, Carassius complex, has been practiced in the Asian monsoon region. We investigated the influences of juvenile crucian carp on the paddy field ecosystem in an experimental paddy field with rice-fish and rice only plots. The numbers of individuals of zooplankton and benthic invertebrates were considerably lower in the rice-fish plots than in the rice only plots, indicating that these organisms were preyed on by juvenile crucian carp. Chlorophyll a values were significantly higher in the rice-fish plots than in the rice only plots. It is most likely that the increase of the phytoplankton biomass in the rice-fish plots was caused by the decrease of abundance of zooplankton and there was a top-down effect by fish foraging. The rice-fish plots also showed significantly lower biomass of aquatic weeds than the rice only plots. Presumably both soil disturbance through fish activity and enhanced phytoplankton biomass increased the water turbidity, and thereby limited sunlight penetration in the floodwater inhibited growth of aquatic weeds in the rice-fish plots. The NO3-N concentration in the rice-fish plots was also higher than that in the rice only plots, suggesting that the positive effects on growth of rice plant through the species interactions exceeded the negative effects.
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  • Muscle biochemical and histological characteristics affecting the meat texture of red seabream (Pagrus major) caught off Kada, Wakayama, Japan
    Nobuyoshi Nakatsuji, Monami Akita, Yoshihiro Hayashi, Shinpei Nomura, ...
    2018 Volume 66 Issue 4 Pages 309-315
    Published: 2018
    Released on J-STAGE: December 20, 2019
    DOIhttps://doi.org/10.11233/aquaculturesci.66.309
    JOURNAL FREE ACCESS
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    Meat texture is one of the most important factors in determining the raw meat (sashimi) quality. It is well known that wild red seabream (Pagrus major) caught off Kada (RK), Wakayama shows excellent meat quality although the reasons for such quality remains unknown.
    The meat breaking strength, an index of sashimi texture, of RK (55.6 gw) was significantly higher than that of cultured red seabream (RC) (34.9 gw). The content of muscle collagen, a major constituent of the connective tissue, was not significantly different between RK and RC. On the other hand, the cross-sectional muscle fiber area of RK (6299.5 µm2) was significantly smaller than that of RC (9524.5 µm2), indicating that the network structure of connective tissue between muscle fibers was denser in RK muscles. These results suggested that the texture of RK sashimi is mainly dependent on the density of connective tissue network structure rather than on the collagen content of the muscle.
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Short Paper
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