Effects of ambient noise on the metabolic level of Crangon crangon (Decapoda, Natantia)

Preliminary observations indicated that the shrimp Crangon crangon (L.) appeared to be affected by the level of the ambient noise expressed as sound pressure. The significance of ~t s metabolic response was studied by comparing its ammonia excretion rate under usual laboratory conditions E (= +25 dB pbar-l) to its rate under sound-proof conditions C (= -4 dB pbar-l). The relationship between these 2 measured excretion rates was expressed by the equation: E = 1.225 C -0.01329 (r = 0.81). Thus a mean 3OdB-increased sound pressure led to a 22 % increase of the ammonia excretion rate; simultaneously, a 15 % increase of the 0, consumption rate was noticed. The metabolic response to a high ambient noise level was fully expressed within a few hours and there was no evidence for any adaptative reduction of metabolic rates over the period of observation (5 d). Shrimpsize and/or -age as much as the noise spectrum should be taken into account when metabolic responses of C. crangon to its acoustic environment are considered.