Does environmental noise really affect reef fish behavior or are they talking while we cannot listen to them?

Abstract

Although it has been hypothesized that reef fish reduces sound production during extreme environmental events, it is possible that fish sounds are still present but only masked by elevated environmental noise. Although available acoustic technology makes it difficult to address this question, we can still generate hypotheses about the impact of environmental noise on fish sound production. Is there a behavioral response to environmental noise, or are fish sounds present at the same levels but masked and therefore undetectable without adequate filters? We recorded sciaenid (Pisces: Sciaenidae) sound production around Isla Tortuga, Costa Rica, during the “Nortes,” a period of strong winds caused by cold fronts and extreme variation of atmospheric pressure. Sciaenid sounds apparently stopped with almost no emissions during strong winds (56 miles/h) and transitioned to the normal emission rate on the next day when winds receded to 2 miles/h. We hypothesize that fish sounds were present at all times, but masked by wind-produced noise instead of a biological modulation as described by Mann and Grothues (2009) in similar conditions. I present circumstantial evidence in support of this hypothesis and discuss possible methods to test it directly.