Contribution to the understanding of sound perception in marine invertebrates

Transcription

1 Contribution to the understanding of sound perception in marine invertebrates Michel André, Kenzo Kaifu, Marta Solé, Mike van der Schaar, Tomonari Akamatsu, Andreu Balastegui, Antonio M. Sánchez, Joan V. Castell

2 GENERAL CONSIDERATIONS AND OBJECTIVES Marine invertebrates may potentially be influenced by artificial noise Exposure to anthropogenic sound sources could have a direct consequence on the functionality and sensitivity of their sensory organs, the statocysts There are gaps in our understanding of marine invertebrate sound perception and consequently of their sensitivity to noise The availability of novel laser Doppler vibrometer techniques has recently opened the possibility to measure whole body vibration (distance, velocity and acceleration), probably eliciting statocyst response

3 Propagating sound waves consist of kinetic components (particle motion) and pressure components (sound pressure). Fish detect the kinetic sound components through the inner ear and lateral lines. Both of these detectors contain mechanosensitive hair cells that act as sensory elements by responding to displacement at a nanometer scale. The lateral lines detect particle motion when a displacement of the sensory cells relative to the receptor epithelium occurs.

4 Propagating sound waves consist of kinetic components (particle motion) and pressure components (sound pressure). Fish detect the kinetic sound components by the inner ear and lateral lines. A fish near a sound source receives different particle motion input at each point on its body. When the fish is further away from the sound source, the particle motion encompasses the whole fish and causes it to move with the same phase and amplitude, without stimulating the lateral line system. In contrast, the otolith organs in the inner ear are stimulated by whole-body displacements.

5 Propagating sound waves consist of kinetic components (particle motion) and pressure components (sound pressure). Fish detect the kinetic sound components by the inner ear and lateral lines. A fish near a sound source receives different particle motion input at each point on its body. When the fish is further away from the sound source, the particle motion encompasses the whole fish and causes it to move with the same phase and amplitude, without stimulating the lateral line system. In contrast, the otolith organs in the inner ear are stimulated by whole-body displacements.

6 CRUSTACEANS MOLLUSCS CEPHALOPODS CNIDARIANS DECAPODS CHORDO - TONAL ORGANS STATOCYST WATER FLOW DETECTORS OCTOPODS ECHINODERMS

7 CRUSTACEANS MOLLUSCS CEPHALOPODS CNIDARIANS CHONDRO - TONAL ORGANS STATOCYST WATER FLOW DETECTORS ECHINODERMS

8 GENERAL CONSIDERATIONS AND OBJECTIVES Marine invertebrates may potentially be influenced by artificial noise Exposure to anthropogenic sound sources could have a direct consequence on the functionality and sensitivity of their sensory organs, the statocysts André, M., Solé, M., Lenoir, M., Durfort, M., Quero, C., Mas, A., Lombarte, A., van der Schaar, M., López-Bejar, M., Morell, M., Zaugg, S., Houégnigan, L. Low frequency sounds induce acoustic trauma in cephalopods. Frontiers in Ecology and the Environment, p.doi: /100124, Available at Solé, M., Lenoir, M., Durfort, M., López-Bejar, Lombarte, A., van der Schaar, M., André, M Does exposure to noise from human activities compromise sensory information from cephalopod statocysts? Deep-Sea Res. II (2012), Solé M, Lenoir M, Durfort M, López-Bejar M, Lombarte A, et al. (2013) Ultrastructural Damage of Loligo vulgaris and Illex coindetii statocysts after Low Frequency Sound Exposure. PLoS ONE 8(10): e doi: /journal.pone

9 Control specimens A 1 Sacrifice & Analysis 1 closed system of recirculating natural seawater (at 18-20ºC, salinity 35 and natural oxygen pressure Exposed specimens B 3 Experimental Tank C Hz sinusoidal wave sweeps with 100% duty cycle and a 1- second sweep period for two hours Sequential Sacrifice & Analysis 2 RL = 157±5 db re 1 μpa with peak levels up to SPL = 175 db re 1 μpa Sacrifice & Analysis 2

10 Controlled Exposure Experiments Results (1/6): SEM. Control Sepia officinalis (A & B); Octopus vulgaris (C & D) macula statica princeps; Octopus vulgaris inner sac statocyst morphology (E) SEM. Sepia officinalis msp, presents different levels of lesions. A-C: sacrificed immediately after sound exposure. D: sacrificed 48h after

11 Results (2/6): SEM. Sepia officinalis (A, B, E) and Octopus vulgaris (C, D) msp, A-D: sacrificed 48h after sound exposure. E: sacrificed 72h after sound exposure SEM. Sepia officinalis msp, sacrificed 96h after sound exposure.

12 Results (3/6): TEM. Cellular organization of control Sepia officinalis (A, C) and Octopus vulgaris (B, D, E) msp LM (A) and TEM (B-E). Octopus vulgaris macula statica princeps (msp), from an individual sacrificed 48h after sound exposure.

13 Results (4/6): TEM. General nervous organization of Sepia TEM. Octopus vulgaris macula statica princeps officinalis macula statica princeps (A, B) and (msp), from an individual sacrificed 48h after afferent and efferent innervations of the sound exposure macula epithelium in the statocyst of Octopus vulgaris Laboratory (C, D). Control of Applied animals. Bioacoustics, Technical University of Catalonia

14 Results (5/6): SEM. Sepia officinalis (A-D) and Octopus SEM (A-E) and TEM (F, G). Sepia officinalis crista. A, B, vulgaris (E, F) crista-cupula system. Control insert in B: sacrificed immediately after sound exposure. animals. C-E: sacrificed 96h after sound exposure. F, G: sacrificed 24h after sound exposure. Insert in G: sacrificed 48h Laboratory of Applied Bioacoustics, Technical University after sound of exposure Catalonia

15 Results (6/6): TEM. Octopus vulgaris crista general morphology (A-C) and nervous organization (D, E). Control animals SEM. Sepia officinalis. Linning ephitelium of animals affected by sound (A-F) and control specimens (G, H)

16 GENERAL CONSIDERATIONS AND OBJECTIVES Marine invertebrates may potentially be influenced by artificial noise Exposure to anthropogenic sound sources could have a direct consequence on the functionality and sensitivity of their sensory organs, the statocysts There are gaps in our understanding of marine invertebrate sound perception and consequently of their sensitivity to noise The availability of novel laser Doppler vibrometer techniques has recently opened the possibility to measure whole body vibration (distance, velocity and acceleration), probably eliciting statocyst response

17 EXPERIMENTAL APPROACH Dense metal bar Fine reflective tape scallop cuttlefish facilities SETUP - Laser vibrometer (Polytec OFV-505 with OFV-5000 controller - water tank (80 x 30 x 40 cm) - Agilent wave generator - loudspeaker and commercial amplifier

18 EXPERIMENTAL APPROACH Dense metal bar Fine reflective tape scallop cuttlefish facilities PROTOCOL Defining (and resolving) sources of uncertainties: - influence of room and tank wall vibration - choice of targets - Laser Doppler Vibrometer calibration - choice of frequencies - distribution of acoustic pressure inside the tank - position of the target

19 INFLUENCE OF ROOM VIBRATION The sound field in a closed space (i.e. room) with rigid walls is characterized by the normal modes obtained from the wave equation. Sound pressure in the enclosure (room) for the frequencies of 60 Hz and 320 Hz. Left plots: walls of the enclosure. Right plots: horizontal plane at the z position of the source. For a pure tone source, the sum of the contributions of the normal determines the shape of the sound pressure inside the enclosure, the frequency of the sound field is the same frequency as the one of the source.

20 EXPERIMENTAL APPROACH Dense metal bar Fine reflective tape scallop cuttlefish facilities The sound field inside the water tank The water tank is again an enclosure but with one open wall. For the directions x and y there will be normal modes as we find in the room. However, since for the z direction there is no upper wall, in the direction z the condition of null particle velocity in this plane is not applicable.

21 INFLUENCE OF TANK WALL VIBRATION - The sound field inside the tank is not only due to the propagation of the sound from the loudspeaker, direct field, and the modal field inside the room, but also due to the vibration of the walls of the tank. Acceleration of vibration in the front face of the water tank for the frequencies of 60 Hz and 350 Hz. Left plots: Loudspeaker inside the room. Right plots: Loudspeaker outside the room. - Measurements were taken at the walls of the tank to help visualize the vibration pattern of these walls at the frequencies of study and experimental conditions

22 PSD (db) CHOICE OF FREQUENCIES bar sepia paper scallop Frequency (Hz) Hz Bar Scallop EU MSFD Descriptors Cuttlefish 103 * 100 * * 115 * Tape Acceleration (peak value) of targets at different frequencies in db re 1e-6 m 2 /s 4 /Hz.

23 LASER VIBROMETER CALIBRATION Dense metal bar Fine reflective tape scallop cuttlefish facilities - Laser calibration using a vibration source working at 160 Hz and 9.8 m/s 2 (140 db re 1e-6 m/s 2 ). - The vibration measurement of a target was considered reliable if it was at least 10 db higher than the vibration of the laser.

24 SOUND PRESSURE MEASUREMENTS Sound pressure levels measured directly under the loudspeaker (pos 2) and the target position (pos 1) for all tested frequencies (left) and levels measured for different wave generator amplitudes at the target position (right).

25 EFFECT OF POSITION ON MEASUREMENTS The consistency of the measurements and the effect of the precise position of the target were tested by measuring the inanimate targets at slightly different positions.

26 TARGET MEASUREMENTS Measurement results of the four targets (reference targets and animals) at the three chosen frequencies, 60, 120 and 320 Hz

27 PRELIMINARY CONCLUSIONS - Little doubt remains that marine invertebrates are sensitive to (i.e. perceive) low frequency sounds and that this sensitivity is not directly linked to sound pressure but particle motion. - The missing component in the analysis was the demonstration that the statocyst would act as an harmonic oscillator, excited when the whole animal body was vibrating when exposed to sound waves. - The differences of the laser Doppler acceleration measurements with the target vibration measurements allow us to conclude that the exposure to sound has elicited the cephalopods and scallops whole body vibration, confirming the initial hypothesis that particle motion can encompass the whole body of cephalopods and causes it to move with the same phase and amplitude

28 FURTHER RESEARCH - Field measurements of particle motion - Further research on the effects of noise sources on marine invertebrates - Quantifying lesions, determining sources and establishing sensitivity thresholds - Extend the variety of species

29 ACKNOWLEDGMENT

30 THANK YOU FOR ATTENTION!