The Sundarbans oil spill did not have any visible impact in the forest floor and long-term monitoring is needed to know the actual extent of damage, an assessment report jointly prepared by the United Nations and the Bangladesh government has concluded.
However, the report said oil contamination in the aquatic ecosystem may hamper physiological activities including breeding of aquatic organisms and disrupt food chain or the food web.
Yesterday, the Dhaka Tribune got a copy of the report, which was published last month.
A 25-member joint team comprising experts from various offices of the UN and the government of Bangladesh conducted a study over a six-day period in the last week of December.
They used site observations, interviews, aerial photography, sampling and other assessment techniques to evaluate the situation and develop recommendations.
The mission’s objective was to strengthen the government’s efforts in containing and cleaning up the oil spillage and provide support to assessing the situation and developing an action plan for a phased response and recovery.
According to the report, loss of breeding capacity, injury to cardiovascular and respiratory organs, and damage to dermis and underlying tissues may occur in longer oil exposure of aquatic organisms.
Inter-tidal zones, shallow creeks, canals and rivers are the ideal places for breeding, nursing and feeding for commercially important fishes, shrimps and crabs as well as dolphins and crocodiles. Eggs, larvae and fingerling of these species can be impacted due to oil contamination. Moreover, intake of oil into the food chain can influence bio-accumulation and bio-magnification to higher tropic levels, which may be of concerns to food security, community health, livelihood and export earnings.
The report recommended controlled navigation through the Sela river and taking appropriate safeguards and mitigation measures to avoid further disaster in the forest immediately to protect the forest from further oil spill incident.
Terming the mangrove ecosystems as the one of the most productive systems in the world, the report said the extent of oil residues observed on the vegetation was not sufficient to require any directed removal action.
It said the action itself and the disturbance associated with bringing personnel into the forest were determined to likely cause more adverse impact than the potential impacts of the oil itself.
The extent and degree of heavy oiling declined dramatically since the first days of the spill and was expected to continue to diminish with time.
The spilled heavy fuel is believed to be less acutely toxic to mangroves, but may be more persistent in the environment over the long-term than a lighter oil, the assessment report said.
It also said impact was limited because of the tidal system which causes the rivers to experience high and low tide twice daily.
The Sela river located inside the Sundarbans was been used as a navigation route illegally since 2011 as the legal route Mongla-Ghosiakhali got unusable because of siltation, encroachment and riverbank cultivation.
Oil tanker Southern Star 7, carrying more than 350,000 litres of furnace oil, sank in the river at Mrigmari area after being hit by a cargo vessel on December 9.
The joint report said that the local people had collected around 68,000 liters of the spilled oil from the river manually, after getting confirmation of receiving cash payment by Padma Oil Company, owner of the oil.
Later, in response to a request from the government, the UN sent an international team of experts to support the ground work.
On Januray 6, the Sela route was reopened despite environmental concerns. The government made the route off limits for heavy vessels since two days after the spill.
The UN experts suggested that the government should adopt special training, equipment and experience to improve response to environmental emergencies.
The report said that the oil had spread at least 20km upstream to Mongla and at least 20km downstream to Horintana in the main shoreline.
However, this differs with the findings of another study conducted by the Environmental Science Department of the Khulna University which said the oil had spread over a nearly 500 sq-km area of the forest.
The Khulna University study also found very limited presence of primary food producers like phytoplankton and zooplankton in the contaminated water and concluded that it was alarming for the flora and fauna of the mangrove forest.
Regrading that report, the UN-government team said Dr Abdullah Harun Chowdhury of Khulna University performed a visual evaluation of the spill region from December 11 to 25 at 15 locations near the spill site and documented 27 oiled animals with species distributions similar in nature to this rapid assessment.
The UN experts said data and photo-documentation from that study was not available during the UN rapid assessment and therefore they could not confirm or reconcile the cases for their report.
