Mangrove stress signals worsen in Costa Mar waters

The monitoring station at Punta Negra, thirty kilometres north of Puerto Azul, recorded a water-column salinity of 37.8 parts per thousand on August 13, the highest reading in five years. Temperature at the same depth held at 29.4 degrees Celsius. The combination suggests a shift in the balance of freshwater input from the inland hydro system and the region's rainy-season runoff.

Marina Castellanos, the network's senior technician, said the readings warrant close attention but do not yet signal a crisis. The mangrove stands near Punta Negra have adapted to seasonal salinity swings for decades, she noted, but the new baseline is pushing them toward their tolerance threshold. The Federal Hydro Authority has been notified and will review whether reservoir discharge schedules need adjustment.

The finding arrives as Costa Mar enters the tail end of its rainy season, when freshwater typically flows most abundantly into the coastal zone. That the salinity remains elevated despite the rains suggests either a longer-term shift in precipitation patterns or a change in how much water the federal hydro grid is releasing downstream. The Authority declined to comment on discharge policy, citing ongoing internal review.