これまで日本では本州以南（青森県以南）でしか知られていなかったトリゲモNajas minor が北海道十勝地方で初めて記録され，国内の分布北限を更新した．発見されたのは，十勝川下流の後背湿地にある豊頃町大沼と，十勝海岸にある生花苗沼の2 湖沼である．豊頃町大沼で採取できたわずかな個体は，塩基配列と形態によって同定を行なった．生花苗沼では2018 年から2019 年にかけて行なわれた調査で継続的に確認でき，形態のみで同定することができた．いずれの湖沼においても過去の水生植物相に関する調査記録がなく，本種が定着した時期は不明である．

In this study, the evolution of the microtopography on a channel bed of the Shonai River during a flood was studied by using the Structure from Motion-Multi View Stereo (SfM-MVS) technique in order to investigate the influence of riparian herbaceous vegetation on the mechanisms of fine sediment trap. The high-resolution surface models of the Digital Surface Model (DSM) which represented the topography of the pre- and the post-flood periods were produced by the results of the SfM-MVS applications. The numerical calculation by using a two-dimensional bed-evolution model was also implemented to evaluate the influences of the hydraulic characteristics of the reach-scale channel topography on the sediment dynamics. The comparisons of the above results showed that the herbaceous vegetation tends to hold fine sediments during the flood. The micro-highlands which were grown by the trapped fine sediment by the vegetation tend to remain on the same places as well, even though they located on the regions where the numerical calculation results implied which tended to be eroded.

The purpose of this study was to identify kinetic characteristics of the support leg due to fatigue during the side-jump test in speed skaters. Ten male skaters performed the 7O-second-maximal effort side-jump test on a tartan track in the laboratory; two synchronized high-speed video cameras (250 fields/s) were used to record their performance using the DLT technique. Ground reaction forces (GRF) of the right leg were determined using the force platform (500 Hz). The GRF and three-dimensional coordinates of the segment endpoints were collected over 70 seconds to calculate the right support leg kinetics during the first and second halves of the test, at 5 and 65 seconds, respectively, using an inverse dynamics approach. During the first half, the absolute work done by hip torque was significantly greater than those of the knee and ankle torques. This indicates that great energy exertion by the hip muscles is a characteristic of the side-jump. During the second half, there was decreased knee extension torque and power at approximately 80% stroke. Thus, minimizing the decrease in the torque and power under fatigue conditions would be an important factor for endurance training of the side-jump.