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A survey of NDT ultrasound transducers for sensing pre-moult tropical rock lobsters, Panulirus ornatus
Abstract
This study examined the novel application of non-destructive testing (NDT) ultrasound for detecting approaching moult in juvenile tropical rock lobsters (TRL), Panulirus ornatus. TRL juveniles are highly cannibalistic in culture, with up to 25% of lobsters lost to cannibalism at each moult. A pre-moult sensor could prove pivotal as moulting lobsters are the primary victim of cannibalistic predation and a reliable indication of pre-moult could trigger a suitable intervention measure. A series of structural changes take place beneath the exoskeleton in preparation for moulting, which leave little indication of pre-moult on the lobster’s external surface. An opportunity exists for penetrative pre-moult detection via ultrasonic acoustic stimulation through the exoskeleton. NDT ultrasound is proposed as a possible pre-moult sensing technology. NDT ultrasound is comparatively low-cost, a requirement for replicated deployment to industry. This study explores the acoustic response from five NDT ultrasound transducers by scanning the dorsal carapace of juvenile TRLs.
A small diameter (13 mm) transducer with a 7 MHz centre frequency produced and measured a low amplitude, long duration signal segment in intermoult lobsters that was not present in pre-moult lobsters, forming a basis to distinguish intermoult from pre-moult lobsters. It is proposed that muscle detachment and growth of the new integument and a separating membrane disrupt sound conduction beneath the exoskeleton in a similar fashion to delaminated joint detection methods used in industry. These results show promise that a pre-moult sensor may be able to be based on NDT ultrasonic technologies and provide guidance for refining transducer specifications for further research.
Sutherland, C., Henderson, A., Holloway, D., Trotter, A.J., Giosio, D., Smith, G., A survey of NDT ultrasound transducers for sensing pre-moult tropical rock lobsters, Panulirus ornatus, Applied Acoustics, Volume 223, 2024, 110073, ISSN 0003-682X,
The ARC Research Hub for Sustainable Onshore Lobster Aquaculture is funded by the Australian Government through the Australian Research Council Industrial Transformation Research Program.
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