Seagrass habitat reduces vulnerability of red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> juveniles to piscivorous fish predator     

Jun Shoji  Kazutaka Sakiyama  Masakazu Hori  Goro Yoshida  Masami Hamaguchi 《Fisheries Science》2007,73(6):1281-1285

ABSTRACT:   Predation experiments were conducted in mesocosms to test the hypothesis that habitat complexity affects vulnerability of red sea bream Pagrus major juveniles to piscivorous fish predators. Juvenile behavior was video-recorded for 6 h in two structurally different habitats: vegetated with sea grass Zostera marina , and unvegetated 0.5-t tanks. Association behavior with seagrass was observed in the vegetated tank throughout the trials. Predation experiments were conducted with 30 red sea bream juveniles (29.9 mm body length) exposed to two individuals of the piscivorous fish predator Chinese sea bass Lateolabrax sp. (261.6 mm), for 6 h in 1.0-t tanks. Predation rate (no. of fish predated on per predator per h) was significantly lower in the vegetated tank (0.02/predator per h) than in the unvegetated tank (0.27/predator per h). Present experiments indicate that habitat complexity reduces vulnerability of juvenile red sea bream to predation by piscivorous fish by serving as physical and/or visual barriers and limiting the predator's ability to pursue and capture prey. Seagrass beds in the shallow coastal waters around Japan are suggested to be an important nursery for red sea bream since they provide the juveniles with habitat complexity as well as serve as a feeding ground.  相似文献   

Offshore currents explain the discontinuity of a fish community in the seagrass bed along the Japanese archipelago          下载免费PDF全文

Atsushi Fukuta  Yasuhiro Kamimura  Masakazu Hori  Masahiro Nakaoka  Tsutomu Noda  Yoh Yamashita  Tsuguo Otake  Jun Shoji 《Fisheries Oceanography》2017,26(1):65-68

Oceanographic conditions can affect spatial variability in fish community structures by influencing the temperature‐dependent latitudinal distribution of adult fishes and transport during their young stages. In order to examine latitudinal variability in the fish community structure within a single coastal ecosystem, quantitative sampling was conducted in the sub‐tidal zone of seagrass Zostera marina beds over a broad latitudinal scale (31.31–43.0°N: from subtropical to sub‐boreal zones, covering 80% of the latitudinal range of seagrass distribution in Japan) in the western North Pacific based on a uniform methodology. Cluster analysis with the similarity of fish communities showed that 13 sampling sites were divided into two clusters. The border between the two clusters corresponded with the area of mixing of two dominant currents, Oyashio and Kuroshio, which form a border between the warm temperate zone and the cool temperate zone off the Pacific coast of Japan. Oceanographic properties, such as major currents off the coast, are suggested to affect the latitudinal variability in the fish communities in the coastal ecosystem in the western North Pacific.  相似文献   

Number and density of retinal photoreceptor cells with emphasis on oil droplet distribution in the Mallard Duck (Anas platyrhynchos var. domesticus)     

Mohammad Lutfur RAHMAN  Masato AOYAMA  Shoei SUGITA 《Animal Science Journal》2007,78(6):639-649

This study was intended to determine the number and regional distribution of photoreceptor cells and different colored oil droplets in the retina of the Mallard Duck (Anas platyrhynchos var. domesticus). To estimate the number and density of photoreceptor cells, adult ducks were killed and both eyes were enucleated under deep anesthesia to prepare Nissl‐stained retinal whole‐mount samples. Different colored oil droplets were counted from color microphotographs of the freshly prepared retina. The mean number of retinal photoreceptors was approximately 6 308 828 ± 521 927, with a peak density of 33 573/mm² in the central retina. The density was similar in the nasal, temporal, ventral and dorsal areas of the retina. Five types of oil droplets were identified on the basis of color: red, orange, greenish‐yellow, yellow and clear. The mean density of oil droplets was highest in the central retina (17 639/mm²) and gradually declined towards the nasal, temporal, ventral and dorsal areas. The size of oil droplets gradually increased with retinal eccentricity and varied even within an area. The greenish‐yellow oil droplets were most abundant across the retina. Taken together, these results demonstrate the differential retinal distribution of photoreceptor cells and oil droplets in duck retina. We conclude that the area of high photoreceptor cell density, which is matched by high neuron densities of the ganglion cell layer, corresponds to the site of acute vision in duck retina.  相似文献   

Distribution and movement of larvae, juvenile and young of the pointhead flounder Hippoglossoides pinetorum in Ishikari Bay and vicinity, Hokkaido   总被引：1，自引：0，他引：1  

Osamu Tominaga  Masamichi Watanobe  Masakazu Hanyu  Kazuko Domon  Yasuhiro Watanabe and  Toyomi Takahashi 《Fisheries Science》2000,66(3):442-451

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Erratum to: Highly polymorphic nuclear microsatellite markers reveal detailed patterns of genetic variation in natural populations of Yezo spruce in Hokkaido     

Masakazu G. Iwaizumi  Mineaki Aizawa  Atsushi Watanabe  Susumu Goto 《Journal of Forest Research》2015,20(3):364-364

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Effects of dietary lysine/protein ratio and fat levels on growth performance and meat quality of finishing pigs     

Keisuke Maeda  Fumika Yamamoto  Masanari Toyoshi  Masakazu Irie 《Animal Science Journal》2014,85(4):427-434

This study aimed to evaluate the effects of dietary lysine/protein ratio and fat levels on the growth, carcass characteristics and meat quality of finishing pigs fed feed made from food waste, including noodles and chocolate. Four dietary treatments, 2 levels of lysine/protein ratio (0.035 and 0.046) and 2 levels of fat (3.3% and 6.0%), were adapted to a 2 × 2 factorial arrangement. Each diet for the finishing pigs contained the same levels of adequate crude protein (16%) and lysine (0.58–0.75%), and similar levels of high total digestible nutrients (90.2–92.6%). In total, 32 LWD pigs with an average body weight of 57.2 kg were assigned to 4 dietary groups. The pigs were slaughtered at about 115 kg. Growth performance was not influenced by the dietary treatments. Carcass characteristics were slightly influenced by the dietary fat level. As the dietary lysine/protein ratio decreased, the marbling score of Longissimus dorsi muscle increased and the intramuscular fat (IMF) increased from 6.82% to 9.46%. Marbling score was not significantly influenced by the dietary fat level. These results indicate that IMF increased without adverse effects on growth, carcass characteristics and meat quality, when pigs were fed a diet with low lysine/protein ratio.  相似文献   

Microbial biomass in soils with calcium accumulation associated with the application of composted lime-treated sewage sludge     

Masakazu AOYAMA  Baoku ZHOU  Masato SAITOH  Norihiko YAMAGUCHI 《Soil Science and Plant Nutrition》2006,52(2):177-185

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Autolysis of unsalted fish protein under pressurization   总被引：2，自引：0，他引：2  

Takashi  OKAZAKI  Yujin  SHIGETA  Yasushi  AOYAMA  Kenji  NAMBA 《Fisheries Science》2003,69(6):1257-1262

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Estimates of numbers of masu salmon caught by recreational fishermen in the coastal area off Iburi, Hokkaido, Japan   总被引：1，自引：0，他引：1  

Yasuyuki  MIYAKOSHI  Tatsuya  KOYAMA  Tomoya  AOYAMA  Shigeru  SAKAKIBARA  Shuichi  KITADA 《Fisheries Science》2004,70(1):87-93

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Lactic acid bacteria effective for regulating the growth of contaminant bacteria during the fermentation of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> (Phaeophyta)     

Motoharu Uchida  Masakazu Murata  Fumiyasu Ishikawa 《Fisheries Science》2007,73(3):694-704

ABSTRACT:   Lactic acid fermentation of seaweed is a recent topic and quite limited information is available on culture conditions. To know the suitable strains for use as a starter culture for seaweed fermentation, 14 lactic acid bacteria (LAB) strains, including 11 species, were tested in culture conditions prepared with or without salt. A commercial product of Undaria pinnatifida powder was used as a substrate for fermentation without sterilizing. Starter-suitability of the LAB strains was assessed from their predominance after culture. Among the tested strains, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus casei and Lactobacillus rhamnosus showed high (>90%) predominance in their cultures, while control cultures prepared without inoculation of LAB did not show any detectable growth of acid producing bacteria and spoiled. A total of 102 strains not showing acid producing activity were isolated and characterized from spoiled cultures, and all the isolates were observed as Bacillus strains, including 64 strains (62.7%) and 16 strains (15.7%) of a Bacillus cereu s-related and B. fusiformis -related species, respectively. The Undaria substrate before fermentation contained culturable microorganisms at 1.4–3.1 × 10² CFU/g, but the Bacillus cereu s-related strain was not a major composition, suggesting a concern of selective growth of the Bacillus cereu s-related strain during the spoiled fermentation.  相似文献