A prototype of an automatic algal monitoring buoy was developed for unattended operation in shellfish and finfish farm waters. The instrument employs novel antifouling and self-calibration strategies (subject to a provisional patent ) based on a battery-powered actuator extending into the seawater medium at 15 min intervals both a light source and a solid state sensor from a protective PVC cylinder. The optical sensor measures both ambient light and the signal from a high intensity LED light source, with separate readings being taken after travelling through an optical fibre reference path (internal standard) and after travelling through a 60 cm horizontal path of natural seawater. The optical system is suspended at 1 m depth (can be varied) from a float with the systems control and data acquisition system located above water.

Financial constraints ($20,000 FRDC budget) prevented us to also implement a radiomodem link to laboratory computer as originally planned. We are now seeking further funds to develop the instrument to a commercial stage (estimated market value per unit Aus $10,000) and extensively test its field performance under a range of environmental and algal bloom conditions.