Anthropogenic or man-made ocean noise, generated from a range of sources, including construction, drilling, seismic exploration, and shipping, is a pervasive global pollutant. Just as how noisy conditions can detrimentally influence our mood and health as humans, animals may also be negatively affected by noise pollution. A new study published in The Royal Society, for instance, shows that fish exposed to noise are less able to fight off disease and prolonged exposure can lead to an early death.
Noise pollution and reduced animal health
Authors Numair Masud from the Schools of Biosciences of Cardiff University and colleagues shared that the detrimental impacts of noise pollution on behavior, immunology, and physiology have been shown in invertebrates and terrestrial vertebrates. Equivalent studies on aquatic organisms have, however, been stunted because of the misnomer “silent underwater world.” The team proves that noise pollution can lead to stress, behavioral changes, and hearing loss in fishes.
To come up with such findings, the team used a mixed strain of ornamental guppies (about 2,000 Poecilia reticulata). On arrival at Cardiff University, all fish were ectoparasite free, confirmed through three consecutive screens using a dissecting microscope with fiber optic illumination. One group of fish was exposed to acute white noise played for 24 hours and another group was exposed to chronic noise for seven days.
Experimental design: acute and chronic noise exposure
All fishes were anesthetized and infected with a parasite. For experimental infections, the Gt3 strain of ectoparasite Gyrodactylus turnbulli was used. Such a parasite population has been maintained in culture pots that contain at least four native fish. For the present study, the researchers infected the guppies either during the noise exposure for the chronic group or after noise exposure in the acute group. Underwater speakers were attached to an amplifier and a laptop to deliver the sound file into each experimental fish tank. The speaker played random, intermitted white noise of 100–10 000 Hz range. There was also a third control group of fishes that were infected but placed in a silent tank.
During the 17-day monitoring period, results show that fishes exposed to acute noise pollution had the highest disease burden. Furthermore, those in the chronic group were likely to die early (day 12). Masud explained via Phys.org that further experiments are needed to determine the exact effect of noise pollution on the immune response.
The team’s findings may have implications not just for fish farms where species reared are highly vulnerable to parasites but also for conservation efforts. Masud highlighted that freshwater fish species, in particular, are facing high levels of species loss. Thus, there is an ultimate need to keep sound pollution to a minimum level so us humans will not increase the mortality levels and disease susceptibility of fishes in the ocean.
There are also studies previously published that highlight the health burden associated with noise pollution created by transportation and human industry. Last November, for instance, a team of scientists from Queen’s University Belfast shows that noise affects mammals, reptilians, mollusks, fish, birds, arthropods, and amphibians.
According to the Center for Biological Diversity, ocean noise is an invisible threat and is often deadly. Over the years, it has become a menace to ocean wildlife. Just as it is now rare to find a mountaintop that is free from aircraft noise, there’s also hardly a place in the world’s oceans where human sounds are not detectable. The most disruptive and the loudest anthropogenic ocean noise come from oil exploration, military sonar, and industrial shipping. It said that naval sonar sounds are like acoustic floodlights. They send sound waves through the ocean waters for about hundreds of miles.
Fish species, threatened
The World Bank Group shared the list of countries with the highest number of fish species threatened as of 2018. It includes the United States (251), India (227), Mexico (181), Tanzania (179), Indonesia (166), China (136), Turkey (131), Australia (125), Cameroon (122), South Africa (121), and Madagascar (111). Meanwhile, countries with the lowest number of fish species threatened include Luxembourg, Lesotho, Chad, Botswana, Belarus, and West Bank and Gaza.
World Hearing Index
Digital hearing app founders Mimi Hearing Technologies GmbH also published the World Hearing Index. It shows the list of cities with the worst noise pollution, including Guangzhou (1.82), Delhi (1.72), and Cairo (1.70). On the other hand, Zurich, Switzerland has the lowest incidence of noise pollution.
So, how can we approach the issue of ocean noise pollution? Conservation Folks suggests making use of large-scale sound maps, just as those used by The National Oceanic and Atmospheric Administration. They are collecting data to better understand the nature of the issue and its impact on sea mammals so they can also build a case for reducing noise pollution. With proper mapping, they can visualize the issue and better accelerate the efforts to address it through regulations, laws, and treaties.
Another solution to prevent and reduce ocean noise pollution is setting new acoustic standards. The National Maritime Organization, for instance, is a UN body tasked not just to improve marine safety but to also reduce ship pollution. Naturally, setting acoustic standards for the ocean will be under their jurisdiction. Their members may have already started the talk about how to limit the noise in the oceans but it needs greater attention, considering the Cardiff University findings that the noise pollution issue can cause the early death of fishes.
Raising awareness will also play an important role. Conservationists can use social media and other platforms to further their mission and spread their message. Through their efforts, there may be individuals who are willing to donate their money and time. More people will also act to save our marine mammals. Furthermore, since gas and oil exploration equipment are harmful to marine life, companies engaged in these practices can instead reassess their exploration methods.
Companies from other countries, like Norway, collaborate or coordinate when they map areas off the coast. With multi-client surveys, group companies can work together so they only have to conduct one survey for seismic data. It is an intelligent strategy to reduce redundant surveys and one that will protect marine life against noise pollution.
Our marine life should be protected from the threats of anthropogenic ocean sounds. Policymakers and industry leaders should contribute to the effort of restoring the balance to aquatic ecosystems around the world.