Effects of low pH on the reproductive behavior of salmonid fishes     

K. Ikuta  Y. Suzuki  S. Kitamura 《Fish physiology and biochemistry》2003,28(1-4):407-410

In northern Europe and America, the acidification of lakes and rivers induced by acid precipitation has damaged fish populations. At present, rapidly expanding industrial activities in East Asia have led to continuous increases in the quantity of emission of acidic pollutants, and rain of acidic levels of pH4 has precipitated throughout Japan. In this way, the effects of acid rain on fish populations have also been manifested in Japan. In order to examine the effects of low pH on the reproductive behavior of salmonids which are known to be acid-sensitive species, changes in the frequency of upstream behavior and spawning-related female nest-digging behavior in response to changes in pH were observed in mature hime salmon (land-locked sockeye salmon) Oncorhynchus nerka, brown trout Salmo trutta and Japanese char Salvelinus leucomaenis. Digging and upstream behavior were significantly inhibited in weakly acidic water of pH 5.8–6.4 formulated using sulfuric acid. Land-locked sockeye salmon was the most sensitive to changes in pH among the three species.  相似文献   

Performance of a closed recirculating system with foam separation, nitrification and denitrification units for intensive culture of eel: towards zero emission   总被引：10，自引：0，他引：10  

Yoshihiro Suzuki  Toshiroh Maruyama  Hiroyuki Numata  Hajime Sato  Makio Asakawa 《Aquacultural Engineering》2003,29(3-4):165-182

The development of a closed recirculating aquaculture system that does not discharge effluents would reduce a large amount of pollutant load on aquatic bodies. In this study, eel were reared in a closed recirculating system, which consisted of a rearing tank, a foam separation unit, a nitrification unit and a denitrification unit. The foam separation unit has an inhalation-type aerator and supplies air bubbles to the rearing water. The growth of eel, which were fed a commercial diet, was satisfactory, with gross weight increases of up three times in 3 months. The survival rate under the congested experimental conditions was 91%. The foam separation unit maintained oxygen saturation in the rearing water at about 80%. Furthermore, fine colloidal substances were absorbed on the stable foam formed from eel mucus and were removed from the rearing water by foam separation. Ammonia oxidation and the removal of suspended solids were accomplished rapidly and simultaneously in the nitrification unit. The ammonia concentration and turbidity were kept at less than 1.2 mg of N per litre and 2.5 units, respectively. When the denitrification process was operated, nitrate that accumulated in the rearing water (151 mg of N per litre) was reduced to 40 mg of N per litre. The sludge was easily recovered from the nitrification and denitrification tanks, and the components were found suitable as compost. Based on these results, the intensive aquaculture of freshwater fish such as eel can be achieved using a closed recirculating system without emission.  相似文献   

A comparative study of self-feeder and automatic feeder: effects on the growth performance of rainbow trout fry     

T Shima  N Suzuki  T Yamamoto  & H Furuita 《Aquaculture Research》2001,32(S1):142-146

  相似文献   

Annual dynamics of marine birnavirus (MABV) in cultured Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> and sea water     

Manami Inaba  Takeshi Kimura  Rika Kikukawa  Mitsuko Iwasaki  Masato Nose  Satoru Suzuki 《Fisheries Science》2007,73(3):615-622

ABSTRACT:   Seasonal changes in the infection state of marine birnavirus (MABV) in Japanese flounder Paralichthys olivaceus and in rearing sea water are described. Sea water and 10–11 healthy fish were sampled monthly from April 2002 to February 2003. The MABV genome was detected throughout the year in > 80% of the fish examined at each sampling. The virus was isolated from the liver, kidney, and spleen, but not from the brain. The detection rate in each organ increased from April to October, and then decreased. Detection of virus antigen by the indirect fluorescent antibody technique also showed that the virus was present from spring to autumn (June–September) in the liver, kidney, and spleen, but not the brain. Sequence analysis of the MABV genome at the VP2–NS region revealed two specific mutations compared to the standard yellowtail strain (Y-6). It is suggested that the infection state of MABV in Japanese flounder changes to a latent or persistent infection after autumn. MABV was detected in sea water between September and February, suggesting that virus particles in the environment are relatively higher during cool seasons.  相似文献   

Accumulation of organotin compounds and marine birnavirus detection in Korean ascidians   总被引：1，自引：0，他引：1  

Kaoru Azumi  Shinji Nakamura  Shin-Ichi Kitamura  Sung-Ju Jung  Keisuke Kanehira  Hisato Iwata  Shinsuke Tanabe  Satoru Suzuki 《Fisheries Science》2007,73(2):263-269

ABSTRACT:   Recently, a serious disease spread extensively in aquaculture sites of the ascidian Halocynthia roretzi in Korea. To understand circumstances of ascidians in Korean aquaculture sites, residue levels of organotin compounds were analyzed, and detection of a marine birnavirus (MABV) in tissues of H. roretzi was attempted. Korean H. roretzi showed high concentrations of butyltins (mono, di, and tributyltins), especially in the gill, hepatopancreas, and digestive tract. However, there was no significant difference in the residues of butyltins in the hepatopancreas between diseased and non-diseased ascidians. The positive rate of MABV detection was high in the hepatopancreas, but also no significant difference was observed between diseased and non-diseased individuals. These observations suggest that an accumulation of tributyltin and a latency of MABV in H. roretzi tissues does not directly relate to the occurrence of the disease.  相似文献   

Identification of ommastrephid squid paralarvae collected in northern Hawaiian waters and phylogenetic implications for the family Ommastrephidae using mtDNA analysis     

Toshie Wakabayashi  Nobuaki Suzuki  Mitsuo Sakai  Taro Ichii  Seinen Chow 《Fisheries Science》2006,72(3):494-502

ABSTRACT:   A total of 110 adult individuals from four ommastrephid (family Ommastrephidae) squid species ( Ommastrephes bartramii, Sthenoteuthis oualaniensis, Eucleoteuthis luminosa, and Hyaloteuthis pelagica ) were used to obtain diagnostic DNA markers for species identification. Restriction fragment length polymorphism (RFLP) analysis of a partial segment (855 bp) of the mitochondrial DNA cytochrome oxidase I (COI) gene amplified by polymerase chain reaction (PCR) revealed that the restriction profiles of two endonucleases ( Alu  I and Tsp 509 I) were diagnostic for species identification. The restriction assay partially supplemented with nucleotide sequence analysis successfully assigned 69 damaged and morphologically equivocal ommastrephid paralarvae collected in northern Hawaiian waters, identifying 60 O. bartramii , eight S. oualaniensis , and one E. luminosa . The family Ommastrephidae appears to be monophyletic. Although the phylogenetic relationships among genera were not resolved well due to apparent homoplasy and large genetic divergence between species, COI sequence data without transitions provided support for subfamily level relationships.  相似文献   

Polymerase chain reaction (PCR) amplification of bacilliform virus (RV-PJ) DNA in Penaeus japonicus Bate and systemic ectodermal and mesodermal baculovirus (SEMBV) DNA in Penaeus monodon Fabricius   总被引：3，自引：0，他引：3  

Y Takahashi  T Itami  M Maeda  N Suzuki  J Kasornchandra  K Supamattaya  R Khongpradit  S Boonyaratpalin  M Kondo  K Kawai  R Kusuda  I Hirono  T Aoki 《Journal of fish diseases》1996,19(5):399-403

  相似文献   

Nutrient digestibility values of a test diet determined by manual feeding and self-feeding in rainbow trout and common carp     

Takeshi Yamamoto  Takao Shima  Hirofumi Furuita  Nobuhiro Suzuki  Manabu Shiraishi 《Fisheries Science》2001,67(2):355-357

  相似文献   

Moisture distribution in rice grains used for sake brewing analyzed by magnetic resonance imaging     

Akemi K. Horigane  Keitaro Suzuki  Mitsuru Yoshida 《Journal of Cereal Science》2014

Water absorption in individual white-core and non-white-core grains of rice varieties used in sake brewing was observed during soaking by magnetic resonance imaging (MRI). Water was absorbed faster in white-core grains than in non-white-core grains and was pooled in the core. Moisture distributions were compared using the line profiles of nuclear magnetic resonance signal intensities (SI profiles) generated from magnetic resonance images of grains soaked for 2 h. SI profiles of white-core and non-white-core grains overlapped despite slight differences in the central and intermediate regions of the grains. A white-core-like structure with loosely packed starch granules was found to exist in the endosperm of non-white-core grains. SI profiles of grains polished to 70% of the yield weight of brown rice were similar in shape to those of grains polished to 90% of the yield, but their overall moisture content was higher after the removal of the hydrophobic grain periphery. A varietal difference in the thickness of the intermediate region, which may affect fissuring resistance in the polishing process, was detected in SI profiles. Differences in water absorbability between parents and their offspring were also apparent from their SI profiles. MRI enabled the detection of variety-specific water-absorption properties in grains.  相似文献   

Effects of steroid hormones on immunoglobulin M (IgM) in rainbow trout, Oncorhynchus mykiss   总被引：3，自引：0，他引：3  

Y.Y. Hou  Y. Suzuki  K. Aida 《Fish physiology and biochemistry》1999,20(2):155-162

The immunosuppressive effects of steroid hormones were evaluated as the response against implanted steroid hormones, cortisol (F), testosterone (T), estradiol-17 (E2), and 11- ketotestosterone (11-KT), in juvenile rainbow trout. In long term experiments (5 weeks), fish were given a single intraperitoneal implant of F or T. A clear suppressive effect of plasma IgM levels with F and T was not necessarily obtained, although mucus IgM levels were reduced corresponding to the elevated plasma steroid hormone levels. In short term experiments (1 week), intraperitoneal implantation of T, 11-KT and E2 suppressed plasma and mucus IgM levels, although the effects were not dose-dependent. When administered through diet, F and T caused a suppression of plasma IgM levels; F administration at both high and low dosages caused a significant decrease in plasma IgM levels, while only a high dose of T caused the suppression. These results suggest that sex steroid hormones, as well as F, have immunosuppressive functions in rainbow trout.  相似文献