The National Marine Fisheries Service (NMFS) recently authorized five companies to survey the ocean for oil and gas deposits using seismic air guns along the Outer Continental Shelf (OCS), from the mouth of the Delaware River to Cape Canaveral, Fla.

The searchable area extends from the shoreline to 403 miles into the ocean – an area of more than 330,000 square miles. An injunction filed by a federal judge during the recent federal government shutdown halted the permitting process until the government reopened.

According to U.S. Rep. Joe Cunningham, an ocean engineer in Charleston, the companies may explore as close as three miles from the coast and people along the shore could hear the seismic blasts underwater.

But there is a bigger issue that could impact Lowcountry economy. “Our primary concern is the impacts on marine life that support our local economy and provide for our unique way of life in the Lowcountry,” he said.

The noise from a seismic air gun can reach 235 decibels under water. That is according to information found at the University of Rhode Island’s Discovery of Sound in the Sea (DOTIS) website.

In comparison, human hearing can be damaged with noises at 85 decibels. A rock band can measure 120 dB, an airplane 140 dB and fireworks usually at 150 dB.

Air gun blasts can be heard as far as 2,500 miles – the distance from New York to Los Angeles – according to a 2012 article in The Journal of the Acoustical Society of America.

Seismic air guns fire blasts of compressed air into the seabed five to six times a minute, continuing for weeks or months. Similar to sonar, information about the ocean bottom bounces back to receivers, revealing buried oil and gas deposits, as well as potential seafloor hazards.

The prospect of seismic air gun exploration being conducted offshore prompted the South Carolina Small Business Chamber of Commerce and several coastal cities and towns – including Bluffton, Hilton Head, Beaufort and Port Royal – to file a complaint in the U.S. District Court for South Carolina against NMFS’s authorization of the seismic air gun surveys.

Among the reasons tourists come to Beaufort County is life around the shoreline. Tourism brings in $1.3 billion to the county, according to the Beaufort County Chamber of Commerce, whether it’s playing golf or tennis or enjoying beach activities.

“Seismic testing affects the food chain out in the ocean and that can impact our recreational fishing and boating,” said Bluffton Mayor Lisa Sulka. “We want people to come here for our beautiful beaches and activities, not to see dead fish wash up on our shores.”

Eric W. Montie, associate professor in the Department of Natural Sciences at the University of South Carolina Beaufort, said seismic air gun exploration could affect recreational fishing offshore.

“One especially important coastal ocean ecosystem within the South Atlantic Planning Area – where seismic air gun exploration is proposed – are ‘live’ hard-bottom habitats that extend from Cape Hatteras to Cape Canaveral, (an area) also known as the South Atlantic Bight,” Montie said.

Among the diverse fish communities that live in that area are snappers, groupers, grunts, porgies, triggerfish, jacks and tilefish.

South Carolina is not alone in its fight against Atlantic exploration for oil and gas. States, organizations and elected officials across the country, as well as along the East Coast, have filed additional documents and introduced bills in Congress.

Cunningham is one of the co-sponsors of H.R. 1149, a bipartisan bill to prohibit the Department of the Interior from issuing certain geological and geophysical exploration permits under the Outer Continental Shelf Lands Act. Seismic surveys for fuel have not been conducted in the Atlantic OCS for 30 years.

“Since most marine life depends on sound to communicate and navigate, blasts have the capacity to disrupt basic survival functions. Seismic air gun blasting can cause catch rates of some commercially and recreationally important fish species to drop by as much as 80 percent,” Cunningham said. “And noise from a single air gun can kill off zooplankton, the organism that underpins the entire marine food chain.”

Zooplankton and phytoplankton are microscopic animals and plants eaten by krill, the primary food source for the largest animal that ever lived – the blue whale. It can fill up on 2,200 pounds of krill.

Montie said more research is needed to determine how seismic air gun noise will impact marine life, but there are numerous studies indicating that the noise can cause mortality, damage hearing and other sensory structures, cause stress, affect behavior, and interfere with the acoustic communication of marine organisms.

In a 2017 study printed in “Nature Ecology & Evolution,” scientists from Western Australia and Tasmania conducted studies in March 2015 on invertebrates. The results showed that experimental air gun exposure in southern Tasmania decreased zooplankton abundance by 64 percent in one hour. All larval krill were killed after the air gun passage, according to the report.

“Zooplankton form the base of the oceanic food chain, and consistent seismic air gun noise over vast areas could impact all higher order predators and ocean health in general,” said Montie.

Cunningham is hoping to prevent any seismic air gun blasting or drilling with his introduction of H.B. 291, the Coastal Economies Protection Act.

“My bipartisan bill would place a 10-year moratorium on offshore oil and gas drilling and seismic air gun blasting off the Atlantic Gulf Coasts,” he said. “Of course, this is just a first step and my ultimate goal is to ensure there is never any drilling off South Carolina’s shores.”

Gwyneth J. Saunders is a veteran journalist and freelance writer living in Bluffton.