A5103239810- Fish Ecology and Management Studies
- Aquatic Invertebrate Ecology and Behavior
- Freshwater macroinvertebrate diversity and ecology
- Fish Biology and Ecology Studies
- Aquatic Ecosystems and Phytoplankton Dynamics
- Fish biology, ecology, and behavior
- Marine and coastal plant biology
- Marine and coastal ecosystems
- Isotope Analysis in Ecology
- Soil and Water Nutrient Dynamics
- Hydrology and Sediment Transport Processes
- Radioactive contamination and transfer
- Marine Biology and Ecology Research
- Geology and Paleoclimatology Research
- Radioactivity and Radon Measurements
- Marine and fisheries research
- Coastal wetland ecosystem dynamics
- Radioactive element chemistry and processing
- Photosynthetic Processes and Mechanisms
- Pacific and Southeast Asian Studies
- Paleopathology and ancient diseases
- Rice Cultivation and Yield Improvement
- Agricultural Systems and Practices
- Ecology and biodiversity studies
- Phosphorus and nutrient management
Ibaraki University
2015-2025
Japan Fisheries Research and Education Agency
2008-2023
National Fisheries Institute
2006
Nagano Prefectural Ueda Senior High School
2002
Nippon Dental University
2002
Tokyo University of Marine Science and Technology
1994-2002
To analyse the effects of small‐scale dams on fish communities, species diversity, population density, biomass, migration over and trophic relationships were investigated in above‐ below‐dam sections three Japanese streams. The 1·5–3·9 m high, constructed within 400 sea, had no impoundment or fishway. Fish communities mainly composed diadromous fishes. Of 17 sampled, only a few gobies, Rhinogobius spp. Gymnogobius able to climb migrate upstream dams. Consequently number species, total...
ABSTRACT The endangered Amami rabbit ( Pentalagus furnessi ), endemic to two Japanese subtropical islands, has a habit of egesting faeces on streambanks in their habitats. We hypothesized that transported into streams are consumed by aquatic animals. Underwater behavioural observations using time‐lapse photography showed decapod crustaceans foraged introduced experimentally forest stream Amami‐Oshima Island. From situ samples, stable isotopic analysis mean contributions diets benthic...
Photosynthetic activities of submerged seaweeds before and after drying were measured in eighteen species collected from different vertical positions a Pacific shore at Shimoda City Japan. The desiccated until the cellular water levels equilibrated with air chamber under various humidities 10 °C. Relative contents all drastically decreased as potentials reduced 0 to −14MPa gradually range −14 −158MPa. Porphyra dentata , which is an upper intertidal species, recovered photosynthetic activity...
Summary 1. In an experimental flume, we examined the effects of a biomass reduction and alteration taxonomic composition, because grazing by fish Plecoglossus altivelis , on net accumulation periphyton. 2. Grazed ungrazed assemblages with different composition were first prepared in enclosures exclosures, respectively. These then set out flume incubated for 2 days under grazing‐free conditions to examine (i) relationship between rate (ii) effect these two. 3. The grazed dominated upright...
SUMMARY Grazing effects of ayu, Plecoglossus altivelis Temminck et Schegel, on the benthic algal assemblages were investigated in Chikuma River, Japan. Comparison composition boulders with and without intensively grazed patches indicated that fish grazing decreased abundance diatoms prostrate filamentous cyanobacteria caused upright to predominate. Differential consumption by ayu was estimated comparing relative algae stomach contents within patches. The results showed consumed...
Zonation has been a major focus of intertidal ecology.In general, sandy beaches are thought to have three zones (supralittoral, littoral, and sublittoral zones).In the present study, 41 areas were surveyed along Japan Sea coast Honshu (from Aomori Yamaguchi Prefectures) characterized by small tidal range, large seasonal fluctuations in mean tide level, harsh wind-driven waves winter, applicability three-zone scheme was examined.Overall, total 316 beach stations surveyed, 28 taxonomic units...
Stoichiometry among 3 thylakoid components, PSI and PSII Cyt b6-f complexes, was determined with the red alga Porphyra yezoensis special reference to regulation of PSI/PSII stoichiometry in response light regime. The ratio abundance four times greater thalli grown under orange which excites mainly phycobilisome, thus PSII, than that preferentially Chl a, PSI. remained almost constant. content regulated separately two growth conditions as also observed Porphyridium cruentum by Cunningham et...
The effects of grazing fish, Plecoglossus altivelis (ayu), on freshwater benthic algal assemblages were investigated by experiments in outdoor water tanks with fish (2.2 indiv./m 2 ) and without for 25 d. To simulate the condition running each tank, a current was generated pump. In three replicate experiments, biomass diatom biovolume reduced presence fish. filamentous cyanophyte, Homoeothrix janthina increased response to grazing, finally predominated Observations scars scanning electron...
Summary 1. Animals exploiting different resources may nevertheless interact if one species indirectly alters the abundance and distribution of food other. To analyse this indirect effect, we conducted experiments in artificial pools field to investigate influence algivorous fish Plecoglossus altivelis (known as ayu) on two insectivorous benthic fish, Pseudogobio esocinus goby Gymnogobius petschiliensis . 2. In pool experiments, algal biomass was not correlated with number ayu, but percentage...
Abstract – Social and foraging modes in fish often vary between individuals with different body sizes populations under ecological conditions. We studied social behaviour of algae‐grazing Plecoglossus altivelis ryukyuensis (Ryukyu‐ayu) inhabiting Japanese subtropical island streams. Ryukyu‐ayu exhibited four behavioural modes: territorial, schooling, solitary floating. Their differed among these modes. Territorial predominantly foraged on benthic algae, whereas schooling frequently consumed...
ABSTRACT The local density of the grazing goby (Sicyopterus japonicus) and benthic algal production were investigated in a 720 m reach Sate River northern part Okinawa Island, Japan. was spatially heterogenous riparian shade divided into three segments (open-canopy, shaded patchy segment) based on vegetation cover. In reach, more abundant open-canopy segment patches than adjacent patches. Between there no significant difference biomass; however, growth rate greater segment. These results...
Although variation among habitats in the ratio of gametophytes to sporophytes has been reported various gigartinacean species, factors controlling phase remain poorly understood. Over 18 months, we examined Chondrus ocellatus at three sites: a sheltered intertidal site, Hiruga A; an exposed B; and subtidal Shikimi. The mean proportion A (73.1%) was significantly higher than that Shikimi (51.2%) B (44.7%). Due water retention ability gametophytes, it expected would exhibit desiccation...
Abstract Grazing fish play a role of controlling autochthonous primary production and converting it to secondary by consuming benthic algae. Moreover, they will also provide particulate organic matter (POM) for freshwater ecosystems dislodging the algal matrix while feeding. However, has not been confirmed whether grazing induce POM during their feeding on To verify this fish, short‐term (90 min) experiments were conducted introducing Plecoglossus altivelis into indoor aquaria with mats. We...
SUMMARY The growth rate and peak biomass of loosely tightly attached layers in periphyton communities were measured slow (39 cm s−1), moderate (67 s−1) fast (137 cms−1) current regimens using experimental channels. The biomasses the highest regimens, respectively. layer was lower regimen than other however, there no significant difference rates layers. These results indicate that restricts accumulation is regimen, while led to a maximization biomass.