SOUNDSCAPE AMBIENT NOISE IN A SETTLEMENT AREA OF WESTERN ROCK LOBSTER (PANULIRUS CYGNUS) PUERULUS

摘要

In Western Australia, western rock lobster (Panulirus cygnus) larvae (phyllosoma) are transported off the continental shelf into oceanic waters, where their limited swimming ability in the early larval stages combined with strong ocean currents results in dispersal over vast off-shore waters, where they develop, up to hundreds of kilometres from the coast of Western Australia [1,2]. After development, the larvae metamorphose and the newly formed pueruli migrate towards the coast settling some 9-11 moths after egg release [3,4]. Triggers for this migration have been suggested to be changes in salinity, sea surface temperature, ocean primary productivity or a critical stored energy level [5,6,7], though these have not all correlated well with locations where puerulus have been previously reported [8]. Previous hypotheses had been that the coastal direction of migration and final location of settlement is driven predominantly by broad- and local-scale hydrodynamics [9]. However, investigation often displayed weak spatial correlations between currents and puerulus settlement [10,11,12]. Recent studies of fish and crustacean larvae, and puerulus have shown they can display impressive swimming capabilities [8,13], the ability to orientate themselves shoreward [14, 15, 16] and a preference for activity during hours of darkness [12,15]. Therefore a combination of swimming and use of wind driven surface waves and/or onshore advection currents is thought a more likely explanation for their movement [6]. The questions still arises, as to what guides pueruli distribution and behaviour, and over what spatial and temporal scale do these drivers apply? A range of factors have been suggested to influence puerulus migration, and their orientation towards the coast. These drivers such as; underwater sound, water chemistry, magnetic fields, celestial cues, hydrodynamic cues and electrosense are being increasingly investigated [8].