The invention discloses a
field device for biologically monitoring
water quality online. The defects that tested organisms need to be fed by foods, the tested organisms need to be replaced periodically, monitoring is limited to a specific
monitoring site and medium / long-term online biological monitoring cannot be realized in the conventional online
water quality biological monitoring are overcome. The scientific requirements of medium / long-term biological monitoring early warning which reflects water
toxicity change in a
natural water body can be met. According to the device, a rule that
hyriopsis cumingii can be subjected to hanging culture in lakes and reservoirs for ingesting
plankton and a
physiological phenomenon that the shell of the
hyriopsis cumingii is tightly closed after the
hyriopsis cumingii is stressed are fully utilized, and the shell motion of the hyriopsis cumingii is induced by using a sensor fixed on the shell of the hyriopsis cumingii, so that the biological
toxicity monitoring of the
water quality is performed. According to the device, a
floating platform and a floating ball are fixed on a
monitoring site by utilizing a
mooring anchor, a
signal emitter is supported by
buoyancy supporting the
floating platform, and the hyriopsis cumingii and the sensor are supported by utilizing
buoyancy of the floating ball, so that the hyriopsis cumingii and the sensor are suspended in the
water body. The shell closing response of the hyriopsis cumingii is induced by utilizing the sensor, a
signal is transmitted to the
signal emitter through a wire, the signal is received by utilizing a signal
receiver arranged ashore for performing analytical
processing, and the water quality is subjected to scientific early warning and monitoring.