Researchers have detected traces of ten common medications in coral samples from the Gulf of Eilat in the Red Sea, raising alarms about the impact of human pharmaceutical use on marine ecosystems.
Among the drugs found, sulfamethoxazole, an antibiotic, was detected in 93 percent of the sampled corals.
“In this first-of-its-kind study, we conducted a large-scale investigation for detection of pharmaceuticals in corals,” Noa Shenkar, lead author of the study, said in a statement. “We were surprised to find an extensive presence of medications even in the deep-water corals—which usually escape contaminations affecting corals in shallower areas.”
The research team sampled 96 reef-building stony corals, some of which lay more than 30 meters below the ocean surface. The results were startling: none of the coral samples, regardless of depth, were found to be free of drug residues.
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Pharmaceuticals detected included antibiotics, blood pressure medications, antidepressants, statins and laxatives, among others. The presence of these compounds, often prescribed to humans, suggests that coral reefs are being exposed to pollutants through wastewater discharge into the sea.
“What does the presence of pharmaceuticals in corals actually mean? Clearly, the corals did not receive a prescription for antibiotics from their doctor,” Shenkar said. “These medications are taken by humans to affect a certain receptor or biological pathway, and they can also impact other organisms.
“There is no reason to believe that corals should be immune to such effects.”
Previous research by the team has shown that certain drugs can disrupt the biology of marine species, with impacts ranging from altered reproductive behaviors in fish to memory damage in squids.
The researchers suggest that similar effects could harm coral spawning synchrony, with potentially disastrous consequences for coral populations.
Shenkar added: “It would take us a long time to notice the problem, and when we do, it might be too late.”
Coral reefs, especially those in the Gulf of Eilat, serve as critical hubs of marine biodiversity. They provide food and habitat for numerous species and support local industries, including fishing and tourism.
“Today, this delicate ecosystem is under pressure as a result of climate change, pollution, and overfishing,” co-author Gal Navon said in a statement. “The presence of pharmaceuticals in coral tissues adds another layer of concern, indicating that human activities even contaminate faraway marine environments.”
Despite the alarming findings, Shenkar emphasized that the intention is not to discourage the use of lifesaving medications. Instead, she called for improved wastewater treatment processes to better filter pharmaceutical residues.
“We must develop new sewage treatment methods that can effectively handle pharmaceutical compounds. Also, each of us must dispose of old medications in ways that do not harm the environment,” she urged.
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References
Navon, G., Nordland, O., Kaplan, A., Avisar, D., & Shenkar, N. (2024). Detection of 10 commonly used pharmaceuticals in reef-building stony corals from shallow (5-12 m) and deep (30-40 m) sites in the Red Sea. Environmental Pollution, 360, 124698.