Acoustical Characteristics of Noise Produced by Snapping Shrimp

Abstract

Some marine animals produce sounds which, under certain conditions, completely dominate the ambient noise in the sea. The snapping shrimp (not to be confused with the edible shrimp) are the most widely distributed of these animals; they are frequently less than 3 cm in length and produces the sound by snapping of the claw. Shrimp noise is likely to be found around the world in tropical and subtropical waters less than 55 meters deep wherever rock, coral, or other material on the bottom provides interstices in which shrimp thrive. This paper describing the acoustic output of the snapping shrimp (Crangon and Synalpheus) is based upon measurements made off the Southwestern and Southeastern coasts of the United States, the Hawaiian Islands, and several islands in the Southwest Pacific. Over a shrimp bed, the noise spectrum is found to be roughly independent of frequency from 2 to 24 k½ (the upper limit of measurement), whereas the ambient noise normally present in the deep sea decreases with frequency. There is a broad peak in the shrimp spectrum somewhere between 2 and 15 kc. Over a shrimp bed the noise at 20 kc is about 25 db above the ambient noise which accompanies a sea state of 2 (waves less than a meter high, not including swell). For low sea states, shrimp noise is appreciable a mile or more from the boundary of the bed. The maximum diurnal variation of shrimp noise is from 3 to 6 db, the noise being greater at night. Single snaps from isolated specimens have been subjected to a Fourier integral analysis which indicates a spectrum comparable to that measured over shrimp beds where the underwater sound consists of a multitude of snaps. A typical peak sound pressure at the distance of a meter from a single shrimp is of the order of 200 dynes/cmL the U.S. Navy Radio and Sound Laboratory (now called the U.S. Navy

Reactions of temperate reef fish larvae to boat sound

“…The underwater soundscape has been the subject of research for decades (Knudsen et al , ). Underwater sound can be of biotic (Everest et al , ) or abiotic (Cato, ) origin, and aquatic fauna in general (Myrberg, ) and fishes in particular (Nelson and Gruber, ) readily detect and utilize sound for a variety of purposes such as predator avoidance (Wilson and Dill, ), prey localization (Bleckmann, ) and habitat choice (Tolimieri et al , ). Some fishes can also produce sounds to communicate with conspecifics, such as in courtship (Lugli et al , ) or territorial defence (Tricas et al , ).…”

Sound production patterns of big-clawed snapping shrimp (Alpheus spp.) are influenced by time-of-day and social context

“…The acoustic activity of snapping shrimp (Family Alpheidae) is a major driver of ambient sound levels in coastal seas (Everest, 1948;Johnson et al, 1947;Lillis et al, 2014;Kaplan et al, 2015). These crustaceans are a widespread and highly diverse family of Caridean shrimp, and produce one of the highest amplitude and most common of all biological underwater sounds, termed "snaps" (Johnson et al, 1947;Au and Banks, 1998).…”

“…Snapping shrimp generally live in large aggregations in structured bottoms of coastal ecosystems (e.g., reef, rubble, rocky shores) (Mathews, 2002b). The snapping of multiple individuals in a colony and multiple colonies in an area results in an audible and ubiquitous crackling sound in locations where they are present (Everest, 1948;Hazlett and Winn, 1962;Lammers et al, 2008). Variation in snapping shrimp sound levels and snap rates have been found to account for much of the habitat-dependent differences in soundscapes, in terms of sound pressure levels and frequency content, within a variety of marine ecosystems (Radford et al, 2010;Lillis et al, 2014;Butler et al, 2016).…”

Acoustic Monitoring of Marine Conservation Areas

“…Humpback whale sounds usually have a fundamental frequency from tens of hertz to 2 kHz, whereas their harmonics could reach up to a few kilohertz (Au, 1993;Au et al, 2006). Snapping shrimp can be a significant broadband noise source in tropical waters, with noise from a few hertz to tens of kilohertz, peaking around 2 kHz (Everest et al, 1948;University of California, 1946). Detection algorithms presented in Processing Toolbox are used in the Conservancy Watch software package to isolate boat detections from humpback whale detections.…”

“…Their frequency harmonics could reach as high as tens of kilohertz but with much lower highfrequency energy. Another significant acoustic source is the snapping shrimp sound, a broadband signal that extends up to tens of kHz (Everest et al, 1948;University of California, 1946). The snapping shrimp signals are present for the entire recorded frequency band.…”