Pakistan, Sept. 17 -- A sudden foul smell has spread across several coastal areas of Karachi over the past few days. The cause has now been identified as decaying phytoplankton, according to WWF Pakistan Technical Adviser Moazzam Khan.

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Khan explained that changes in sea temperature can cause large amounts of phytoplankton to die. These microscopic marine plants are then carried towards the shore by waves. As they decompose along the coastline, they release gases that create an unpleasant smell.

He said the seasonal transition also affects marine vegetation and the coastal ecosystem. The end of the monsoon season and weaker winds can contribute to changes in marine ...