Acoustic monitoring can be used as a tool to monitor biodiversity
Spiny lobsters raise an undersea racket that can be heard miles away
Friday, May 29, 2020, 05:00 (GMT + 9)
European spiny lobsters can create a sound that might, under the right conditions, be detectable up to 3 kilometers, nearly 2 miles, away.
Researchers used underwater microphones to determine how loud lobsters are, and found that the larger the lobster, the louder the sound.
Spiny lobsters were overharvested in the 1970s, and though populations have rebounded, there is still a need to monitor population levels.
The study suggests that lobsters may be a candidate for acoustic monitoring.
European spiny lobsters create quite the rumble. By rubbing an antenna across its face, a spiny lobster can create a sound that might, under the right underwater conditions, be detectable up to 3 kilometers (1.9 miles) away.The sound, known as an antennal rasp, occurs when an extension of a lobster’s antennae moves across a rough patch under its eye. Lobsters likely make this sound for communication or to scare away predators.
In a recently published study in Scientific Reports, researchers asked, how far does the sound of a rasp travel? And can these sounds be used in a non-invasive way to monitor lobster populations?
A large spiny lobster held by a scuba diver during a bioacoustic experiment. Photo by Erwan AMICE/CNRS.►
Spiny lobsters (Palinurus elephas) are found in the Eastern Atlantic Ocean and in the Mediterranean Sea. Intensive fishing of lobsters for food in the 1960s and 1970s made spiny lobsters scarce in European waters and even led to local extinctions off southwest Britain. Though populations have rebounded, there remains a need to monitor and manage lobster populations from overharvesting.
Using hydrophones (underwater microphones that record sound from all directions), researchers recorded 1,560 antennal rasps from 24 individual lobsters in the Bay of Saint Anne du Portzic, France. They placed hydrophones at distances of 10, 20, 50 and 100 meters (33 to 330 feet) away from each lobster. The largest lobsters (with a carapace, or body shell, 13.5 centimeters long, or about 5 inches) made sounds detectable at 100 m distance; in general, the larger the lobster, the louder the sound.
The density of seawater allows sounds to travel over greater distances compared to air. However, sound is still lost in the water, and noise pollution can get in the way of a good recording. Seismic surveys, used in oil and gas exploration, are one of the most common sources of noise pollution.(continue...)
Author: Liz Kimbrough / news.mongabay.com | Read full articlehere