Karachi’s coastal regions are experiencing a strong, unpleasant smell linked to recent monsoon rains and tidal surges.

Experts attribute this odour to the decay of marine plants, particularly phytoplankton. Mohammad Moazzam Khan, an adviser at the World Wide Fund (WWF) Pakistan, explained that the foul smell results from rotting phytoplankton that washes ashore at the close of the monsoon season.

Khan highlighted the presence of Noctiluca scintillans, commonly known as Sea Sparkle, which is part of the phytoplankton community. He cautioned that such plants can change the sea’s colour to green and may be toxic, contributing to increased mortality rates among marine life.

He added that the foul odour lingers for hours or even days when such organisms wash ashore.

Khan noted that phytoplankton thrives underwater during the monsoon season, leading to significant blooms. Such dinoflagellates are commonly found along Pakistan’s coastline, particularly during the pre-monsoon (April to May) and post-monsoon (September) periods.

Experts stress the critical role of phytoplankton in the Earth’s ecosystem, as they generate about two-thirds of the planet’s oxygen and are essential to the global food chain, supporting marine life and overall ecological balance.