For the first time, researchers have filmed what happens when ships’ anchors and chains drag across the seabed in Antarctica.
In one video, the camera pans across a barren seabed with lines and grooves along the substrate where anchors have dragged, with a few crushed sponges scattered nearby.
Another piece of footage compares this eerily empty scene with an undisturbed area of seafloor right next to it. Where the anchor didn’t hit, there is a smorgasbord of life of all different shapes and sizes.
The videos have been released alongside a new study published in Frontiers in Conservation Science.
“This is the first time the impacts of ship anchoring and chain damage are documented in Antarctic waters,” says the study’s first author Matthew Mulrennan, a marine scientist and founder of the ocean exploration and conservation nonprofit KOLOSSAL.
“The observed damage was a near miss to three giant volcano sponges, believed to be the oldest animals on the planet which may live up to 15,000 years,” he says. “Many other species, including Antarctic sun stars, giant Antarctic octopus, sea spiders and a variety of fish were recorded at anchorable depths.”
Many different types of vessels visit Antarctica, including cruise ships, research boats, fishing fleets and private yachts – over 195 vessels were recorded in Antarctic waters shallow enough to anchor (under 82.5 metres deep) during the 2022–3 season. There may also have been more that didn’t have licenses (and therefore weren’t recorded).
When these ships drop anchor, it can damage the vulnerable marine life below, but the study authors believe the conservation impact of this seabed destruction is understudied and overlooked. "It’s a pressing environmental issue, but it’s out of sight, out of mind,” says Mulrennan. “Activities in Antarctica have a lot of strict rules around conservation, yet ship anchoring is almost completely unregulated.”
In this first-of-its-kind footage, the realities of anchor damage are laid bare. “Documentation is way overdue, given the importance of these ecosystems and the protections we place on them,” says co-author Sally Watson, a marine geophysicist at the National Institute of Water and Atmospheric Research in New Zealand.
Many of the ocean species demolished by the anchors can only be found in Antarctica and are very slow growing so it takes them a long time to recover from threats.
The scientists hope more studies will explore how damaging anchoring can be to these unique ecosystems and how long it takes the seabed to recover. Finding ways of mitigating anchor damage and protecting marine life is important for both nature and people.
"The weird and wonderful animals that are impacted, like sponges, are important for filtering water, carbon sequestration, and providing shelter, food and complex habitats which benefit the whole marine ecosystem, including penguins and seals,” says Mulrennan, highlighting that these are “the animals tourists come to see.”
Image and video credit: Matt Mulrennan / KOLOSSAL
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