Pakistan coastal waters turn green near coastal areas, particularly along the Balochistan coast near Gwadar, Pasni, Jiwani and Ormara,due to an algal bloom. Marine experts and environmental organisations say the phenomenon is natural and non-hazardous, despite concerns raised on social media.
What Is Causing the Green Colour?
According to the Gwadar Development Authority (GDA), strong winds and sea currents have pushed large quantities of algae toward the shoreline. Along with decomposing sea grass, this has led to foul smells in some coastal areas.
Officials say the bloom is caused by a marine organism known as Noctiluca scintillans, which is known to multiply rapidly under certain oceanic conditions.
Algal blooms occur when algae grow quickly in seawater, changing its colour to green, red, brown or blue, depending on the species involved.
Rising Frequency Along the Balochistan Coast
The GDA notes that over the past decade, the frequency of algal blooms along the Balochistan coastline has increased significantly. Previously, such events occurred once every one or two years, but they are now being observed two to three times annually.
Marine researchers link this trend to warming sea temperatures, which create favourable conditions for the growth of organisms like Noctiluca.
Bloom Spread Across the Arabian Sea
WWF-Pakistan says the current bloom is not limited to Pakistan. The algal growth has extended to Iranian waters and earlier this season spread as far as Karachi’s coastline.
At present, Noctiluca blooms are visible along much of Pakistan’s coast, with higher concentrations between Pasni and Jiwani.
WWF-Pakistan has been monitoring Noctiluca since 2012 and reports its presence every winter, usually between November and February. In some years, the bloom spreads across unusually large areas.
Is the Bloom Dangerous?
Marine experts stress that the current algal bloom is non-toxic. No fish deaths or ecological damage have been reported along the Sindh and Balochistan coasts.
Studies conducted since 2012 show that nearly all Noctiluca blooms observed in Pakistan have been harmless. The organisation also clarified that linking this bloom to pollution or nutrient waste is scientifically incorrect.
A Natural Marine Phenomenon
Scientists explain that winter algal blooms are a natural feature of the northern Arabian Sea. They are influenced by the upwelling of cooler waters and the formation of ocean eddies during the winter months.
Although Noctiluca itself is not green, the colour appears due to a symbiotic organism living inside it. The species is also known for its ability to produce bioluminescence, which can create glowing scenes in the sea at night.
2017: A Regional Bloom Event
Experts recall that in 2017, an intense Noctiluca bloom spread across much of the Arabian Sea, affecting Pakistan, Iran, India, Oman and parts of the Gulf region.
Environmental groups emphasise that while the sight of green seawater may look alarming, it is not a sign of contamination and does not pose a threat to public health or marine life.
