Coral reef off the coast of Fagamalo, Savai'i, Samoa - Rickard Törnblad via Wikimedia Commons

Reef damage and small oil leaks from Manawanui wreck – Expert Reaction

Samoa’s Marine Pollution Advisory Committee (MPAC) has confirmed that the capsized HMNZS Manawanui is leaking residual oil from three locations. 

The oil leakage is from the service tanks in the engine room where the fire broke out. It is believed that the majority of the fuel was burnt out, and that the residual oil coming out of the sunken vessel is reducing each day.

Yesterday, MPAC confirmed damage to the reef from the shipwreck and anchor chain. Assessments show the area of physical destruction to the reef is roughly half the size of a large rugby pitch.

The Science Media Centre asked experts to comment. Feel free to use these comments in your reporting or follow up with the contact details provided.


Associate Professor Nick Ling, School of Science, University of Waikato, comments:

“MPAC has reported that physical damage to the reef arising from impact by the ship, the ship’s anchor and chain, and the stranding of three shipping containers is limited to an area of approximately 5000 square meters. This is encouraging news that damage to the reef is not more extensive, but removal of those items from the reef will be a priority to prevent further damage occurring from their movement due to wave action.

“News that ongoing oil leaks are slowing and appear to be limited to fuel or lubricants contained in engine room service tanks is also encouraging and suggests that the main fuel bunker tanks remain intact. However, there is clearly considerable urgency to remove stranded heavy items from the reef and the fuel contained in the wreck before the arrival of the cyclone season.

“While coral reefs can naturally recover from such physical damage this process can take many years depending on the scale of damage, although this can be facilitated by physically reattaching coral fragments. However, this can only be undertaken once debris from the wreck has been removed and the method is also dependent on the ability of divers to work in such relatively exposed conditions.”

Conflict of interest: None


Dr Bridie Allan, lecturer, Department of Marine Science, University of Otago, comments:

“Recent reports suggest that the HMNZS Manawanui is leaking oil into Samoan waters across three locations. Although, there are presently no reports of oil slicks reaching land, it appears as though surface oils are dissipating quickly.

“However, this does not reduce the risk of contamination. For example, as oil is agitated at the surface due to wave and wind energy, the chemical components, including highly toxic heavy metals and polyaromatic hydrocarbons (PAHs), in the oil are weathered out. This results in the release of these chemicals into the water column where marine organisms may encounter them. Very small doses of these chemicals have been demonstrated across multiple scientific studies to cause a range of physiological effects such as cardiac, spinal and craniofacial deformities as well as behavioural impairments following exposure to low levels of PAHs.

“It seems likely that increasing levels of oil will be released over the coming days presenting more of a significant threat to this ecologically and economically important ecosystem. The effects of a catastrophic oil spill can persist over a long period as the chemical components of oil are absorbed by marine organisms and deposited in marine sediments. This can continue to have lasting effects of the fitness of populations of exposed animals.”

Conflict of interest: None