Humans are noisy creatures, our cacophony of jet engines and jackhammering drowning out the communications of other species. In response, a number of animals, including marmosets and whales, turn up their own volume to be heard above the din, a phenomenon called the Lombard effect. A new study reveals that even fish “shout.” Researchers took a close look at the blacktail shiner (Cyprinella venusta), which is common to freshwater streams of the southeastern United States and whose short-distance acoustic signals are often exposed to boat and road noise. Only male shiners make sounds; popping sounds called knocks are used aggressively toward other males, while staticky-sounding “growls” are used for courtship, both heard in the above video. When the scientists brought the fish back to the lab and cranked up white noise from an underwater amplifier, they found that shiner males emitted fewer, shorter pulses, and cranked up the volume of their acoustic signals to be heard above background noise. Published in Behavioral Ecology, it’s the first study documenting the Lombard effect in fish, suggesting that freshwater fish are another group potentially impacted by our ever-increasing hubbub.
(Video credit: Dan Holt)