Noise elicits the Lombard effect in midshipman mating vocalizations

Anthropogenic noise pollution is an emerging global threat to fish populations. Among a suite of deleterious effects, noise can potentially impede reproductive success in some fishes by masking their mate advertisement vocalizations. Using the plainfin midshipman fish (Porichthys notatus), a marine toadfish that produces a distinctive “hum” during courtship, we investigated how noise affects male vocalizations and spawning success in the wild. We recorded nesting males for three days and measured the frequency, amplitude, and duration of their vocalizations before, during, and after exposure to artificial noise (a c. 118-Hz tone). We also counted eggs in nests exposed to 10 days of artificial noise versus control nests that were not exposed to artificial noise. Males exposed to noise reduced the number of vocalizations they produced, reduced the frequency of their vocalizations, and increased the amplitude of their mating hum (Lombard effect). However, chronic noise exposure did not clearly affect spawning success, suggesting that the Lombard effect allowed males to sustain clear advertisement signals when competing with the relatively weak artificial noise source.

Noise elicits the Lombard effect in midshipman mating vocalizations Journal Articles