CRUISE ships moored off the Dorset coast have 'scarred' and 'destroyed' the seabed, causing 'very significant damage', a new report has found.

Since the start of the pandemic in March last year, some of the world's biggest and best-known cruise ships have anchored in Poole Bay, Weymouth Bay and Portland Harbour, becoming a tourist attraction for locals and visitors.

Now, in a new sonar study carried out by Dorset Wildlife Trust (DWT), it has been revealed that the impact of the ships repeatedly dropping their anchors has 'scarred' and 'destroyed' the seabed.

The study found that between October 8, 2020 and January 5, 2021, five cruise liners anchored in Poole Bay and, during this time, the vessels either moved around or left and returned such that, between them, they dropped anchor at least 28 times.

Peter Tinsley, marine policy and evidence manager at DWT, said: "After concerns were raised to us about the number of large cruise ships anchoring in and near Dorset's marine protected areas, DWT organised surveys that showed the impacts on the seabed can be considerable.

"Where anchoring has occurred in protected areas, this potentially can harm delicate reefs and other sensitive habitats.

"Whilst the ships have usually responded to requests to move, we found that often they were not aware of the zones that they should be avoiding.

"Ideally, such large vessels would keep to designated anchorages, but there is not enough space for the current demand. The most sensitive seabed features - and those could be archaeological as well as ecological - should be protected. That requires a bylaw to provide the legal protection and for the features to be identifiable on navigational charts.

"The arrival of these cruise ships along the south coast has brought with it an additional pressure on the marine environment. We do not know how typical this scar is, nor do we know the sensitivity of the habitats at the other anchoring sites.

"Data from multibeam survey around anchoring sites in soft mud in Weymouth Bay suggest that the impact of anchoring is wider than that detected by this sidescan survey – there is likely to be a fan of scraped seabed at one end of the chain scar caused by dragging of the chain at the vessel end. As the ship moves around the anchor in different weather/tide conditions, this could impact an area of several hectares – this could have a very significant impact on a delicate, highly localised habitat."

Dr Alice Hall, researcher at Bournemouth University, is concerned that marine life will be unable to survive after the ships destroyed their habitat.

She said: "The extent of damage is very significant, with large areas of the seabed destroyed. This marine habitat destruction is a global issue and coupled with other impact such as climate change will have a serious effect on the biodiversity of the seas.

"Without hard, rocky reef for marine life to live on, it will not be able to survive."

A spokesman for TUI and Marella Cruises – one of several operators that had ships moored off Dorset – said: "Sustainability is a core value for TUI and Marella Cruises, and as such we operate with the utmost respect for the environment. We strive to comply with marine protection requirements and always evaluate an area prior to anchorage to assess its suitability.

"Information on Marine Protected Areas has been shared across our fleet so everyone onboard has awareness of the sensitivity of the sites. We will continue to work with local coastguards in order to minimise the potential environmental impact of anchoring."