Streams in the Karnaphuli suddenly turned black at the Maheshkhal point. A thick layer of diesel oil was floating on the surface water.
Grasses, shrubs and small trees coated with oil on the banks seemed burnt, oil-smeared bodies of dead crabs and some other aquatic insects were seen afloat on water, giving an impression how oil spill into the river during a Friday tanker accident has taken toll on the river.
During a visit to different points of the Karnaphuli on Sunday, The Business Standard's Chattogram team found a similar sign of environmental damage at Dangarchar or the Ghat-5 too on the opposite bank of the Maheshkhal point.
While crossing the river on a ferryboat, our team also saw water hyacinths and other floating substances wearing a thick coat of black oil. Oil was seen on rocks and trees on this bank too.
A boatman at Dangarchar, Mohammad Farkruddin, told The Business Standard they faced difficulties on Friday in rowing their boats due to a thick layer of oil in the water.
However, our Chattogram team, during their Sunday visit, hardly found any presence of oil at the Padma jetty area in the Chattogram port where Khulna-bound oil tanker Desh-1 hit an anchored lighter vessel, City-38, leading the tanker to leakage.
The accident at the early hours of Friday caused spill of at least 10,000 liters of diesel into the Karnaphuli River. Oil spread around 16 kilometer areas in the river and adjacent canals.
Environmentalists said the tanker accident would take short- and long-term tolls on aquatic species of the Karnaphuli and its nearby canals.
Dr Shafiqul Islam, a professor at the marine science and fisheries department of the University of Chittagong, said, "Primarily, aquatic species will face suffocation and will eventually die, while in the long run their habitat will be destroyed."
"Karnaphuli is the breeding ground of the Ganges Dolphins. After breeding in Karnaphuli, they move to the Halda and the Sangu. Such accidents will destroy their breeding ground which is already under threat due to pollution," he said.
"Such accidents are alarming. We urge the port authority to conserve the breeding area to keep the dolphins' route undisturbed," he added.
Professor Dr Mohammad Al Amin of the Institute of Forestry and Environmental Sciences from the University of Chittagong, said the massive oil spill caused by the tanker accident in the Karnaphuli River will threaten the very survival of its marine species.
It will put the Karnapuli's biodiversity in peril by wiping out hundreds of fish species, said Al Amin.
"The oil spill will cause oxygen depletion in the water, which will lead to breathing problems of these dolphins. Microbes and fish living in the surface levels of the river will be destroyed," he added.
However, Captain Faridul Alam, deputy conservator of the Chattogram Port Authority, said they have already removed over 80 percent of the oil from the water. "Our patrol team is working to clean the oil completely."