Sea turns green in Gwadar due to natural bloom

Experts say green waters along coasts of Balochistan and Karachi pose no toxic threat

KARACHI:

The sea off Gwadar has taken on a striking green hue, with its deep blue waters transformed by the natural phenomenon known as Noctiluca bloom. Similar activity was last observed in 2017, when its effects spread beyond Pakistan’s coastline to the entire Arabian Sea, including Iran, India, Oman and the Persian Gulf.  

According to Abdul Rahim of the Gwadar Development Authority, large portions of water in both the eastern and western bays of Gwadar have turned green. In response, WWF-Pakistan issued a clarification, noting that this seasonal change is not unusual. The organization has monitored Noctiluca blooms since 2012, which typically occur during winter months (November to February) and can spread widely.  

WWF explained that the phenomenon is often misinterpreted as eutrophication or linked to cyanobacteria growth, but scientific studies show otherwise. The green coloration results from the presence of Noctiluca scintillans, a small, free-floating organism that can appear red, orange, green or colorless. Along Pakistan’s coast, it is most often green or orange, expanding rapidly under seasonal conditions. Though the organism itself is not green, the color comes from its internal symbiont Protoeuglena noctiluca, which enables fast growth.  

WWF technical advisor Muhammad Moazzam Khan stressed that the green water poses no toxic threat. No fish or marine life deaths have been reported, and long-term monitoring confirms that Noctiluca blooms along Sindh and Balochistan’s coasts are non-toxic. He added that while the bloom is sometimes wrongly associated with pollution, it is in fact a natural oceanic process. At night, the presence of Noctiluca often produces a luminous glow, adding to its distinctive appearance.