may be ヤマイヌワラビ (Athyrium vidalii) or タニイヌワラビ (Athyrium otophorum).
In our plot we saw two Buckeye Ohio, one was 41 cm at DBH, with a good condition and got full sunlight and the other one was 27 cm at DBH, with a poor condition and partial sunlight. Each leave has five leaflets and its bark is light gray to light brown.
Contents of a water, explored throug a "microscope" mode, made by revesing lens.
This specimen was definately moving, sized less then half millimeter.
Location shows the pool where the water was taken from.