Anthropogenic sound and marine mammal health: measures of the nervous and immune systems before and after intense sound exposure

Abstract

Anthropogenic sound is a potential stressor for marine mammals that may affect health, as has been demonstrated in other mammals. Therefore, we have initiated investigations on the effects of intense underwater sounds on nervous system activation and immune function in marine mammals. Blood samples were obtained before and after sound exposures (single underwater impulsive sounds (up to 200 kPa) produced from a seismic water gun and (or) single pure tones (up to 201 dB re 1 μPa) resembling sonar “pings” from a white whale, Delphinapterus leucas, and a bottlenose dolphin, Tursiops truncatus, to measure neural-immune parameters. Norepinephrine, epinephrine, and dopamine levels increased with increasing sound levels and were significantly higher after high-level sound exposures (>100 kPa) compared with low-level sound exposures (<100 kPa) or controls (P = 0.003, 0.006, and 0.020) for the white whale. Alkaline phosphatase decreased over the experimental period (P < 0.001), while γ-glutamyltransferase increased over the experimental period (P < 0.001). Significant neural-immune measurements for the dolphin after exposure to impulsive sounds included an increase in aldosterone (P = 0.003) and a decrease in monocytes (P = 0.006). Neural-immune changes to tonal sound exposures were minimal, although changes were observed in multiple neural-immune measures over time.