Study on Response of Physical Phenomena to Wetland Ecosystem in Large River Mouth

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1) Field survey of the habitat distribution of Genus Uca that is classified "Near Threatened species" were carried out on river-mouth flats in seven prefectures. The relationship between bed material properties and inhabiting density was examined by using the neural network analysis.2) To accumulate the basic data for verifying the numerical simulation, water qualities and zooplankton were observed in the Yoshino river mouth. To investigate the response of physical phenomena to wetland ecosystems, at the same time, 2D river-bed variation program and quasi-3D flow simulation program were improved and examined their accuracy.3) A detailed meshed vegetation map is presented based on the results of a full vegetation survey. Two methods to predict plant community distribution were proposed. One is a method using the preference curve developed the concept of PHABSIM (Physical Habitat Simulation System) and the other is the neural network analysis.4) Field observations were carried out in five wetlands in the Yoshino river estuary during 1999 and 2000. The distribution of Ocypodidae was investigated and a distribution pattern prediction model was developed. The assimilation function of organic matter by a common Ocypodidae Macrophthalmus japonicus was examined quantitatively to evaluate one of the wetland ecosystems worth.5) New practical methods to utilize the eigen functions obtained by Principal Component Analysis (PCA) were proposed. They can be succeeded to extract the temporal periodicity and the spatial path of sand movement, which are important for understanding the topography change.