NEW OPTIONS IN PHYSIOLOGICAL AND BEHAVIORAL ECOLOGY THROUGH MULTICHANNEL TELEMETRY

This paper is intended to acquaint physiological and behavioural ecolo gists with the options offered by modern telemetry technology, and enc ourage collaboration between biologists and engineers. When direct obs ervation is impossible, telemetry can be used to acquire a wide spectr um of environmental, physiological and behavioural data. This spectrum is expanding rapidly due to dramatic increases in the availability of miniaturized, micropower transducers and electronic components. The ' 'pros and cons'' of telemetry are presented, particularly with referen ce to crustaceans in marine systems. The kinds of phenomena that now c an be telemetered are listed, alongside representative devices that tr ansduce them into electrical signals. Transduced data may be stored fo r subsequent uploading, or transmitted over radio or ultrasound carrie r waves. Radio is most useful in air, ultrasound in saline (conductive ) water. Data can be encoded on pulsed or continuous carriers, dependi ng on the data rate needed; common schemes are summarized. A sequence of questions about crab ecology is used to illustrate how both simple and complex telemetry systems can provide unique data sets and provide significant insights into the biological system. Simple tracking tran smitters provided time budgets for ghost crabs [Ocypode quadrata (Fabr .)], revealing that they are predators rather than scavengers. Single- channel behavioural transmitters have provided detailed spatial and te mporal data on how blue crabs (Callinectes sapidus Rathbun) move about while seeking moulting sites or food, and where they feed or moult. A multichannel system incorporating microcontroller-based ''smart'' tra nsmitters and multiple receivers integrated with a data-reduction unit is providing automated logging of feeding and threat behaviours, as w ell as location within a field enclosure, for multiple blue crabs. A r ationale is presented for incorporating telemetry technology into a re search programme. An incremental approach that involves experienced co llaborators is most likely to yield results quickly and minimise expen diture of resources.