WILLEMSTAD - A new scientific study conducted on Curaçao’s coral reefs by the University of Amsterdam has found that coastal development is causing multiple forms of pollution in nearby coastal waters—especially following periods of heavy rainfall. The research, carried out over the past three years, was published this week in the journal Marine Pollution Bulletin.
The research team analyzed the chemical composition of common algae species along the island’s southern coastline. Because algae absorb substances from their surroundings, their chemical makeup serves as an indicator of the nutrients and pollutants present in the water. In essence, the algae functioned as natural “recorders” that allowed scientists to assess the environmental conditions at each location.
“It’s certainly no surprise that Curaçao’s coastal waters show signs of pollution,” said lead author Nienke van de Loosdrecht. “But until now, we lacked detailed information about which specific substances are present, where they accumulate, and in what quantities.”
To fill that knowledge gap, the researchers measured nitrogen isotope levels (δ15N) in algae tissue—a widely used method to detect the presence of sewage in coastal waters. They also measured the concentrations of 32 additional elements. This chemical “fingerprint” revealed not only the levels of nutrients such as nitrogen and phosphate, but also the presence of heavy metals like copper, zinc, and lead, which can be toxic to coral reef organisms when present in high concentrations.
Certain elements also pointed to pollution linked to specific coastal activities, including the oil industry and drinking water production.
At sites with intensive coastal development, the study found higher δ15N values consistent with sewage contamination. These areas also showed elevated levels of heavy metals. In contrast, sites with little or no coastal development exhibited significantly lower concentrations of pollutants.
“These measurements clearly show that pollution in coastal waters is a mixture of sewage and toxic substances directly linked to human activities along the coast,” van de Loosdrecht explained. “Rainfall plays an amplifying role—during wetter periods, runoff increases and more pollutants are carried into the sea.”
The findings confirm that both the type and intensity of land use along Curaçao’s shoreline have a major impact on the chemical pressures facing nearby coral reefs. The study also demonstrates that areas with limited development maintain relatively low levels of pollution, underscoring the ecological value of protecting minimally disturbed coastal zones.
Further research is expected to help local authorities better understand pollution sources and strengthen measures to protect the island’s vulnerable reef ecosystems.