To most people, the ocean environment seems like one of serene silence. In reality, it’s a smorgasbord of sound. And not all of the noise is helpful to the marine life inhabiting it.

In January, the Trump administration proposed opening up more than 90 percent of U.S. coastline to offshore oil and gas drilling. Seismic testing surveys would accompany that plan, threatening to make the ocean a much noisier and more dangerous place for marine mammals and other sea life.

Seismic testing generally involves an array of air guns pulled on the back of a large boat. The guns release bursts of highly pressurized air into the water, sending soundwaves to the ocean floor and back in order to detect reservoirs of oil and gas. The blasts are loud—according to the Center for Biological Diversity, they can reach up to 250 decibels, and the noise reverberates for miles. 

Currently, five companies have submitted applications to conduct seismic testing to the National Oceanic and Atmospheric Administration (NOAA) Fisheries, which is charged with reviewing them. According to the Natural Resource Defense Council, if the permits are approved, the companies will be towing between 24 to 40 air guns through the water, blasting simultaneously every 10 seconds, 24 hours a day for months on end.

Mounting evidence suggests that this kind of high-volume, constant noise significantly harms marine mammals by damaging their hearing and interrupting their efforts to communicate with one another.

“[The ocean] is like a healthy orchestra,” says Michael Stocker, acoustician and executive director of Ocean Conservation Research, a nonprofit based in San Rafael, California. “You’ve got the bassoon, the snare drum, the flute, the whole thing. All of those niches are occupied by animals making sounds.” Seismic testing disrupts this orchestra, making it hard for individual animals to detect each other’s calls.

Whales are particularly vulnerable to the impacts of seismic testing because they need to hear at low frequencies (the same levels at which the blasts occur) to locate family, mates, and food. Seismic testing can also obscure the clicking noises they make to find their way with echolocation, causing them to become disoriented and more likely to beach themselves. 

John Calambokidis is an expert on Pacific marine mammals who has studied blue, humpback, and gray whales for the past 30 years. He points to studies that suggest whales are finding it more difficult to locate high-prey areas because of industry noise. 

Calambokidis says that on the West Coast, up to 2,000 blue whales, one of the largest populations in the U.S. to have survived commercial whaling, could be negatively impacted by the surveys. “These animals already face stress; adding another activity puts these really important populations at risk,” he says.

Seismic testing harms marine mammals in more indirect ways, too. Recent research conducted by Robert McCauley, an associate professor at the Center of Marine Science and Technology in Western Australia, demonstrates how it can damage even tiny organisms at the bottom of the food chain.

In 2013, McCauley and his colleagues took samples from areas through which air guns were passing. They found that the seismic pulses created a chemical signature, or “dead zone,” which was present even an hour after the air guns left the area.

“It suggested something dramatic happened to the plankton,” McCauley says. He and his team found that the mortality rate of plankton was three times higher in the air-gun zone than for the control group. While the exact cause of death of the plankton in the wake of air gun pulses remains unclear, McCauley says that some plankton seemed to have died instantly. “They can’t get out of the way,” he says. Zooplankton is one of the main food sources for krill, on which baleen whales subsist.

A healthy marine ecosystem is important in its own right, but it also contributes significantly to coastal economies. One of the reasons why the moratorium against surveying has been held in place for so long is tourism.

“Whale watching is a huge economic driver,” Calambokidis says. “Both recreationally and economically, these concerns outweighed the benefits of oil and gas exploration.”

Todd Miller, the executive director of the North Carolina Coastal Federation, echoes the sentiment.

“We are very worried about it,” Miller says about opening up the North Carolina coast to drilling. “It’s really incompatible with the nature we have here.” He points out that more than 100,000 marine mammals can be found along the coast at different times of the year. “We are in the dead of winter, and dolphins are swimming around right now,” he said. “There’s no window that would be a good time for [seismic testing] to happen.” The North Carolina coast also remains a temporary stopover for North Atlantic right whales, an endangered species that was decimated by commercial whaling in the 1700s and 1800s.

If the Trump administration has its way, and huge swaths of coastline are opened up to drilling, then marine mammals will have to contend with the effect of multiple surveys blasting their air-gun arrays at the same time. “There is no consideration for cumulative impacts that will occur from three concurrent surveys being conducted in relatively close proximity,” Stocker wrote in a blog post about ocean noise. “So, if a group of North Atlantic right whales needed to escape the area of a survey, they could easily be pushed into an area of another survey,” a factor that he worries is not being adequately considered by government agencies. 

In light of the scientific evidence, seismic testing doesn’t make sense, especially given that questions remain about just how effective it is in the search for oil and natural gas deposits. In the summer of 2015, Royal Dutch Shell started exploratory drilling and seismic testing in the Arctic’s Chukchi Sea. By September, it pulled out after one exploratory well proved dry. During the exploratory drilling, immeasurable noise pollution entered the dark, Arctic waters. In its application, Shell had estimated that more than 2,500 bowhead whales, 2,500 gray whales, and 50,000 ringed seals might be exposed. 

If approved, the permits would need to be granted exemptions from the Endangered Species Act, which would allow for a “negligible amount” of harm, as defined by NOAA Fisheries, to come to certain marine mammals. But according to Stocker and other researchers, there is no such thing as a “negligible amount” of harm for species that are already endangered. “The sounds of industry are colonizing and masking their biological niches,” said Stocker. “It’s stressing the animals out.”