Silt and shadow: how shipping lanes are smothering Costa Mar's reefs

The water off Punta Negra was cloudier than usual on a Tuesday morning in early August, and not because of the weather. Dr. Andrés Soto, a marine biologist with the Costa Mar Reef Monitoring Network, descended through the haze to a monitoring station at eighteen meters, where soft corals that had been thriving in June now showed signs of stress. The polyps were partially retracted, their colours dulled. Soto's team had been documenting this slow decline since May, and they knew the cause.

The increase in container-ship traffic from Oriente Moderno's Nueva Singapur terminal has intensified over the past eighteen months, and the vessels' passage through the shallow waters west of Puerto Azul is stirring up sediment that smothers the reef. The problem is not new, but the scale is. Monitoring data show that sediment plumes now appear on roughly 60 percent of shipping days, compared to 20 percent in 2022.

The Costa Mar Reef Monitoring Network operates five stations along the northern reef corridor, taking water-chemistry readings and photographic records twice weekly. The data feed into a federal database maintained by the Marine Ministry, but the findings have sparked little formal response from Meridian beyond acknowledgment. Meanwhile, the reefs continue to receive sediment loads that they evolved to handle only during rare storm events.