Author: Ellie Wang
Editor: Kira Tian
Artist: Cici Zhang
Amidst waste and warming water, there is another environmental issue affecting oceans: the increasing levels of anthropogenic, or human-caused, noise. It may seem trivial, but discerning sound is a way for aquatic organisms to communicate and navigate in the oceans. Without the natural soundscape of the oceans to follow, organisms are left under great stress. In addition, the increased noise can cause direct harm to organisms, injuring or even killing them.
First, what does anthropogenic noise consist of? Some of the noise is the byproduct of using huge ships to transport goods around the world. Leila Hatch, a NOAA marine ecologist, states that cargo ships are used to “transport over 98% of the world’s goods.” Offshore drilling for oil and gas is also a significant contributor to the noise. Moreover, intentional usage of anthropogenic noise, such as using seismic air guns to map out areas of the ocean floor, also contributes to noise creations. In particular, seismic air guns have a large impact on the soundscape of the ocean: “they have been detected 4,000 kilometers away,” said Douglas Nowacek, a Duke University professor of marine conservation technology.
According to Nature, this noise has been increasing for decades, “Researchers agree that ship traffic approximately doubled between 1950 and 2000, boosting sound contributions by about 3 decibels per decade. That translates to a doubling of noise intensity every 10 years since the magnitude, or doubling, of sound increases every 10 decibels”. These sounds drown out natural sounds produced in the ocean, such as calls between organisms or the bubbling of oxygen from underwater plants. Shots from seismic air guns reach up to about 260 underwater decibels—about 200-atmosphere decibels. Cargo ships max out at 190 underwater decibels—about 130-atmosphere decibels. To put the numbers into perspective, a space shuttle launch produces sounds of 160 decibels for anybody nearby.
Marine organisms suffer from a multitude of negative effects caused by the cacophony. For instance, clownfish larvae are unable to swim until they have matured enough; they also drift away from home after hatching. In order to find their way back, they have to listen for the soundscape of the coral reef—the popping of oxygen bubbles, the chittering of animals, and other such sounds. Without this auditory guide, the clownfish is unable to return to the coral reef. Furthermore, anthropogenic sounds can also directly bring harm to marine life. Some negative effects include impaired hearing, brain hemorrhaging, and overpowering of sounds animals make to communicate. They even cause gradual or swift death: a study on zooplankton resulted in the deaths of almost two-thirds of the population in a 0.75-mile radius. Zooplankton is an important food source for many organisms, and the decrease in their populations would greatly upset the balance of the ecosystems.
Various solutions are available to quiet the noise emitted by humans: machines can be replaced with quieter designs, transport ships can be slowed down, and vulnerable areas can be avoided. In order to preserve oceans and the life they contain, this lesser-known problem requires a lot more attention and response to it.
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New York Times, 27 Jan. 2019, www.nytimes.com/2019/01/22/science/oceans-whales-
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