Aug 10

The German government is to investigate soundproofing underwater construction sites with a ‘bubble curtain’, to protect whales, dolphins and porpoises in the Baltic Sea.  

A recently released report by the German Federal Agency for Nature Conservation suggests that by using simple, low-cost technology, bubbles released from pipes on the seafloor can create a sound-insulating barrier around developments such as turbines. This simple, yet innovative technique should help protect vulnerable marine mammals from noise pollution.

Photo of adult female Risso's dolphin with young

Adult female Risso's dolphin with young

As countries accelerate their attempts to ‘green’ their economies, offshore wind farms are becoming increasingly more prevalent. While the turbines seem peaceful enough as they harness the wind’s energy, their construction can result in serious noise pollution that threatens underwater mammals like whales, dolphins and porpoises. 

At particular risk are the cetaceans that inhabit the Baltic Sea off the northern German coast – a prime area for wind farm construction. 

Need for an acoustically clean environment 

Marine mammals rely on echolocation to hunt and navigate, and noise from pile-driving work to install turbines can interfere with the animals’ ability to find each other and locate their prey. Young animals can be separated from their mothers, while older animals can suffer hearing loss. 

Karsten Brensing, a biologist at the Whales and Dolphins Conservation Society said: “These animals are so dependent on their acoustic sense … we need an acoustically clean environment.”

Photo of dunlin and sanderling flock flying past a wind farm

Dunlin and sanderling flock flying past a wind farm

However, a German study has shown that by creating a ‘bubble curtain’ it is both technically and economically feasible to reconcile the drive for green energy with protecting aquatic life. 

A pipe or hose is placed on the sea floor to create a ring around noise pollutants, like a pile-driver attempting to break through bedrock. Air is then pushed through holes to create a shield of bubbles around the noise. As sound waves pass through the resulting bubble curtain, they become less intense and noise levels are decreased.

Photo of harbour porpoise underwater

Harbour porpoise underwater

A Greenpeace campaigner, Thilo Maack, believes that if bubble curtains can mitigate the impact on wildlife, they should be used. But he also said quieter construction methods such as drilling need to be investigated. 

We have to be sure that the wind parks don’t harm harbour porpoises and other marine mammals,” Maack said. “On the other hand, we need these renewable energies to fight the consequences of climate change.” 

Read the full article at the Guardian – German ‘bubble curtain’ study hopes to protect whales’ hearing.

Alex Royan, ARKive Species Text Author