A benthic environmental telemetry station

A remote sensing unit has been developed to continuously monitor the benthic environment in selected kelp beds in the Santa Barbara Channel area. To characterize their environment, light distribution, temperature and water motion are monitored. Light distribution is determined by a six channel spectral irradiance photometer. Temperature is sensed using a thermistor in a linearizing constant voltage bridge over a range of 8 to 22 degrees Celsius with a resolution of 0.2°C. A capacitive transducer, immune to fouling by debris has been developed to supply wave height data. Bidirectional benthic surge currents are sensed by a silicon strain gauge bridge. The information is multiplexed at a sample rate of 250ms per channel, FM encoded and transmitted to shore about one kilometer along a line of sight. The system has been designed using low power circuitry enabling unattended operation for up to one month on standard 12 volt marine batteries.