New Zealand naval ship the HMNZS Manawanui ran aground near the southern coast of the island Upolu in Samoa before sinking on Sunday morning.
The ship is a specialist dive and hydrographic vessel that is used to carry out a range of support, salvage and survey tasks, and crew on board had been conducting a reef survey.
People living in villages on the southern coast of Upolu report the strong smell of oil, highlighting concerns about an oil spill.
The SMC asked experts to comment.
Professor Chris Battershill, Chair in Coastal Science, University of Waikato, comments:
“The effect of ship hulls on coral reef systems can be quite damaging, because a lot of the antifouling paint comes off and gets ground into the corals. Where that can be cleaned up, then recovery of the corals can happen quite quickly. If it’s left there, particularly if it’s some of the older style anti-fouling paints that have tin in them, the effects can be quite long-lasting.
“There will of course be oil escaping out of the ship right now. I’m hearing stories that people can smell petrol onshore, and it looked to me like there was an onshore wind. Very much the same as we experienced with the Rena, the smell of hydrocarbon fumes was overpowering. Ordinarily if there’s a slick coming out of the ship, if there’s high tide, strong winds and waves, then a lot of the more toxic components of that oil can evaporate. What ends up on the beach is a sort of chocolatey mousse mixture, which can be picked up. Once again with the Rena experience and the massive volunteer army that came out – they manually picked up all of the oil that came ashore, taking it out of the environment, which stopped it re-engaging and causing more problems.
“What we’ve learnt both from the Rena, and the three significant grounding events on the Great Barrier Reef, is that if you can reduce the amount of fuel lost from the vessel, and remove any crushed coral rubble contaminated by the old-style anti-fouling paints as best as possible, recovery of those reef systems is surprisingly quick. I never stop being amazed at the resilience of the sea despite everything we seem to be throwing at it at the moment. So that’s a good thing but I guess it’s only up to a limit.
“When I heard of this wreck, my first thoughts were of dismay – the crew and the vessel were out there doing some very much needed work of real importance. It’s quite surprising that even to this day, we need to renew surveys of coastal shore regions from areas that have been surveyed to some extent in the past, but really not well enough. As recently as about 5 years ago, the Ningaloo Reef – the second largest reef in Australia – was surveyed for the first time in detail. So this work is essential for not only the people of Samoa, but for all shipping that might happen around it.”
Conflict of interest statement: No conflicts of interest. Professor Battershill has dived in this area in Samoa before, and has relevant knowledge regarding the Rena and similar ship groundings on the Great Barrier Reef.
Associate Professor Nick Ling, School of Science, University of Waikato, comments:
Tuesday 8 October, 9am: “The most immediate threat to the local reef ecosystem stems from the release of fuel oil which appears to be already occurring. My understanding is that this is light fuel oil, similar to diesel, so presents less threat than heavier fuels such as crude oil or the heavy fuel oil that spilled from the Rena shipwreck. Much of that light fuel material will quickly evaporate or disperse so, although it is toxic and will potentially affect the immediate reef environment, any damage is likely to be quite localized. Spill recovery efforts are likely to be challenging given the exposed nature of the site and the dangers for any salvage vessels working in such close proximity to the reef.”
Tuesday 8 October, 3.30pm: “Media have reported that the Samoan Conservation Society has observed limited effects of the fuel leaking from the wreck. This is encouraging, although it is still very early days. Reports of dead turtles are concerning but not unexpected.
“The nature of fuel oil, whether light fuels like diesel or heavier fuels like crude, is that because they are lighter than water, they concentrate at the ocean surface. Any animals that need to interact with the surface are therefore going to come into contact with the oil. Seabirds that land on the surface and any animals that must reach the surface to breath air will therefore be most affected, such as marine reptiles (turtles and sea snakes) and marine mammals (whales and dolphins).
“Those animals may ingest the oil or aspirate it into their lungs while breathing. Aspirating a lung-full of diesel would obviously be catastrophic. Those animals won’t know of the presence of the fuel until they reach the surface and take a breath and they may randomly find the only patch of fuel in an area.”
No conflict of interest
Professor David Capie, Director, Centre for Strategic Studies, Victoria University of Wellington, comments:
What was this ship used for and what does the loss of this ship mean for our naval capabilities?
“HMNZS Manawanui was a multi-purpose vessel. It had some really advanced capabilities for navy divers, and was also able to survey the seabed, reefs and harbours in order to update charts and improve maritime safety. It has a 100-ton crane on board which means it could be used to quickly unload containers of aid in the case of a natural disaster.
“Recently it’s been helping government agencies like DOC and GNS Science with their work on Raoul Island, and earlier in the year it was removing unexploded World War II ammunition from the waters around Tuvalu.
“The loss of the ship is a huge blow to what is already a small navy. New Zealand’s navy has been under huge pressure in the last few years because of a lack of people, especially in some highly skilled positions like senior maritime engineers. That’s meant we simply couldn’t put a lot of ships to sea.
“New Zealand had six ships it could use before the loss of the Manawanui. When you think about New Zealand’s enormous maritime environment and the increasing calls on the Defence Force for responding to disasters, fisheries patrols, as well as a much more challenging strategic environment, and you only have five ships, that’s a really concerning place to be.”
No conflict of interest
Dr Peter Greener, Senior Fellow, Centre for Strategic Studies, Victoria University of Wellington & Honorary Professor, NZDF Command and Staff College, comments:
What was the ship used for?
“HMNZS Manawanui was a specialist hydrographic survey vessel and dive support ship, which also had the ability to undertake salvage work. Originally built to support commercial operations in the oil and gas exploration industry in the North Sea, she entered service in 2003.
“The ship was provided with sophisticated operating capability from the outset, with positioning systems which would allow for a high degree of stability when undertaking hydrographic work or supporting diving operations. As such she was an excellent choice when bought by New Zealand for service in the Royal New Zealand Navy. HMNZS Manawanui has been in service since November 2021 and at the time it was anticipated that she would have a service life of fifteen years.
“As a dive support ship, Manawanui removed World War II ordnance in Tuvalu in 2022 and in 2023 she undertook the disposal of World War II bombs in Niue, Fiji, and Vanuatu.
“As a hydrographic survey vessel, in 2022 she undertook a hydrographic survey of the Tongatapu outer reef in Tonga. Manawanui then conducted undersea surveys in 2023 in Niue, Fiji, and Vanuatu.”
What might the salvage operation look like?
“The salvage operation will be difficult and complex. Specialist equipment is available but the first priority is to limit the environmental damage.”
What does the loss of this ship mean for our naval capabilities?
“The Minister herself commented on the capability of NIWA’s ship, RV Tangaroa and its ability to undertake hydrographic survey work. However, the ship has a very busy schedule so may have very limited availability. Some of the work Manawanui undertook could be done by other Navy ships but this would be limited.”
No conflicts of interest