A New Technique for Remote Monitoring of Freshwater Invertebrate Populations,

摘要

The use of thermistor probes for remote non-invasive monitoring of the vertical movement of freshwater invertebrate populations was demonstrated. The system consisted of a rectangular column constructed of plexiglass. A bipolar arrangement of stainless steel and electrodes (20mesh/inch; 0.023gauge wire,type 304) were cemented on opposing walls in series 10cm apart. These electrodes were then connected by shielded cable to a Brush Impedance Coupler (model 11-4307-06) which utilized an excitation frequency of 50KHz and maximum excitation current of 1.5 milliamperes. The signal output from the impedance converter was then amplified and monitored on Brush 440multi-channel recorders, a cathode ray oscilloscope,and a 3watt audio monitoring system. The system has been used to monitor individual species for twenty days at a time with excellent results.