The relation between the type of antenna pigments of dominant cyanobacteria and the ambient stratification condition in reservoirs.

We found from field observation data in two reservoirs that the hydraulic state affect the type of antenna pigments of dominant cyanobacteria. To clarify the processes of this phenomenon, we analyzed theoretically the effects of hydraulic states on phytoplankton community based on characteristics of absorption by antennna pigments and underwater light regime. By theoretical analysis we found that phycocyanin-rich cyanobacteria (PC-type) favor shallow stable stratification based on the relationship between the absorption characteristics of antenna pigment and red light penetrative ooptical condition. Furthermore, this hypothesis can also explain the growth condition of bloom forming cyanobacteria. This stratification condition can be estimated as the critical buoyancy frequency(N²cr). This hypothesis is verified using field data.Article信州大学山地水環境教育研究センター研究報告 2: 97-103(2004)departmental bulletin pape

Population dynamics of water hyacinth (Eichhornia crassipes)

Water hyancinth (Eichhornia crassipes (Mart.) Solms) is a perennial, herbaceous, aquatic weed of the family ontederiaceas. Water hyacinth is considered as a serious pest in many part of the world in the tropical and sub-tropical regions due to its prolific growth affecting water resources adversely by blocking canals and pumps in irrigation projects; interfering with hydroelectricity production; wasting water in evapotranspiration; hindering boat traffic; increasing waterborne disease; interfering with fishing and culturel; and clogging rivers and channels so that drainage is impossible and floods results. A dynamic numerical model was developed to simulate the growth dynamics and production of water hyacinth. Two state variables, shoots and roots, were considered to illustrate the growth of the water hyacinth. The net growth of the shoots was imperative effects of photosynthesis, repiration, mortality and allocation for root growth. Biomass data reported in literature was used calibrate the model. Model parameters were allowed to vary as a result of acclimation, following experimental data reported in literature. Model simulations show a good agreement with observed data with asimilar biomass temporal dynamics.Article信州大学山地水環境教育研究センター研究報告 2: 35-40(2004)departmental bulletin pape

Age specific rhizome dynamics of Phragmites australis and their effects on nutrient cycling.

Characteristics of rhizome resource storage of common reed, Phragmites australis (Cav.) Trin. Ex Steudel, were investigated associated with the aboveground biomass in terms of rhizome age category. Age-specific rhizome biomass and total nonstructual carbohydrate (TNC), and standing stock of aboveground biomass were observed monthlu. The biomass of one- or two-year old rhizomes did not reduce during the growing season, while a large reduction was observed with older rhizomes. TNC concentration declines twice a year, first in May before the recovery in late spring and second after August, followed by recovery in November. The amount of remobilized TNC is negatively correlated to rhizome age during spring growth and autumnal translocation, except for one year old rhizomes. Analyses of carbon budgets implies that the spring decline is caused by the remobilization of TNC for the aboveground biomass growth and rhizome respiration, and that of autumn is mainly due to respiration, while translocation of dead shoots contributes to the subsequent recovery of rhizome biomass. The nitrogen contents substantially decrease decrease during the second summer, however, phosphorous contents reduce gradually during the whole year.Article信州大学山地水環境教育研究センター研究報告 2: 47-52(2004)departmental bulletin pape

Evaluation of belowground seasonal dynamics of Typha angustifolia after cutting treatment

Typha angustifolia, an emergent macrophyte, shows different growth characteristics under the influence of external forces. In this study, the growth characteristics of T, angustifolia were investigated after cutting the shoots (treatment area: 3m×4m). The treatment is considered as an external force. Two stands, one in a sterile zone and the other in a fertile zone, were cut at the end of June 2001 and the subsequent re-growth characteristics were observed. The difference of response, after cutting their shoots in the fertile zone and sterile zone was prominent. Shoot re-growth model was developed to evaluate the belowground dynamics by calibrating the choot height and aboveground parameters. The belowground biomass of cut area after one year was simulated to be about 80% of that of uncut area. The results were verified using the belowground biomass observed in April 2002. The buds in the cut area are shorter than those of the uncut area. Morever, the cut area in the ferile zone generated thinner buds than that of the sterile zone. The belowground biomass and re-growth strategy after cutting were supposed to cause the differences of their buds the year after.Article信州大学山地水環境教育研究センター研究報告 2: 29-34(2004)departmental bulletin pape

Effects of the Ambient Stratification Condition in Eutrophicated Reservoirs on the Type of Antenna Pigments of Dominant Cyanobacteria

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Citizen’s Perception on Eco-friendly Lifestyle for Conserving Endangered Oriental White Stork and Crested Ibis Bird Species in Japan – Case Studies in Toyoka, Sado and Konosu Cities

This study aims to find out the relationship between an eco-friendly lifestyle and the attitude towards conservation of endangered Oriental White Stork and Japanese Crested Ibis bird species in Toyooka, Sado, and Konosu cities in Japan. Citizens were surveyed to assess their willingness to spend an eco-friendly lifestyle to protect the above-mentioned endangered bird species through questionnaire surveys. Ecological Mind Evaluation Scale (EM Evaluation scale) developed by Tanaka and Joh (2012) based on Hirose model and Bandura’s research on Self Efficacy was applied in this research. This Ecological Mind Evaluation Scale includes 10 factors and it was applied to develop the questionnaire survey. The factor analysis was undertaken based on 4 groups of questionnaire results; environmental awareness, attitude towards environmental conservation, environmental consciousness and self-efficacy.Factor analysis was performed using the varimax method and sample data set comprised 686 valid responses from the three study sites. The KMO values were over 0.80 indicating the sampling was adequate. According to the factor analysis Sado city scored high forenvironmental awareness and environment consciousness. Toyooka city scored high on self-efficacy and environmental consciousness. Konosu city was compared with the Toyooka and Sado cities, where more advanced habitat conservation activities are already implemented. Findings displayed that the citizens in Konosu city had low awareness about these birdconservation activities, however, they are willing to contribute in such activities in the future. Thus, this study demonstrated that by engaging in environmentally friendly lifestyles, the citizens can contribute to habitat conservation of endangered bird species

Plants in aquatic ecosystems: current trends and future directions

Aquatic plants fulfil a wide range of ecological roles, and make a substantial contribution to the structure, function and service provision of aquatic ecosystems. Given their well-documented importance in aquatic ecosystems, research into aquatic plants continues to blossom. The 14th International Symposium on Aquatic Plants, held in Edinburgh in September 2015, brought together 120 delegates from 28 countries and six continents. This special issue of Hydrobiologia includes a select number of papers on aspects of aquatic plants, covering a wide range of species, systems and issues. In this paper we present an overview of current trends and future directions in aquatic plant research in the early 21st century. Our understanding of aquatic plant biology, the range of scientific issues being addressed and the range of techniques available to researchers have all arguably never been greater; however, substantial challenges exist to the conservation and management of both aquatic plants and the ecosystems in which they are found. The range of countries and continents represented by conference delegates and authors of papers in the special issue illustrate the global relevance of aquatic plant research in the early 21st century but also the many challenges that this burgeoning scientific discipline must address

Fractionation of Stable Isotopes of Nitrogen in Trapa japonica During Uptake of NH4+-N

Trapa japonica grown hydroponically under various conditions with respect to different concentrations of NH4+-N to observe the fractionation of stable isotope of nitrogen occurred during uptake and assimilation. There was a significant variation in fractionation of nitrogen isotope during uptake from different levels of nitrogen by the plant. When plant absorbed a large amount of N from the solution, the lower enrichmentof δ15N value was observed in plant parts and the enrichment of δ15N value was decreased with the increase of nitrogen concentration in the medium. A linear relationship occurred during up take of nitrogen by T. japonica between fraction of nitrogen remaining inmedium (f) and fractionation factor (ε)