The number of African penguins on St. Croix Island in Algoa Bay, once the largest breeding colony of these birds in the world, has plummeted since South Africa began allowing vessels from the region to refueling at sea, a process known as “bunkering”, six years ago, according to the study.
Located in a busy shipping lane along the east coast of South Africa, Algoa Bay is rich in marine life and birdlife, where southern right whales roam its sheltered waters.
“We have seen that noise levels, which were already high, have doubled” since bunkering began, Lorien Pichegru, acting director of the Coastal and Marine Research Institute at Nelson Mandela University, who led the study.
High noise levels affect the ability of marine animals to find and herd prey, communicate or navigate properly, scientists have previously found.
“This year we are at 1,200 St Croix breeding pairs, compared to 8,500 pairs in 2016, a decrease of almost 85% since the start of bunkering in South Africa,” said Pichegru. “I counted the dead birds every month on the beach of the bay”.
The new study, published August 10 in the peer-reviewed journal Science of the Total Environment, is the first to explore the impact of noise pollution from shipping traffic on a seabird, and the consequence of offshore bunkering activities on underwater noise levels, the researchers said.
In 2016, the Maritime Safety Authority of South Africa (SAMSA) awarded the country’s first offshore bunker operator license Aegean Marine in a controversial closed tender, then awarded two subsequent SA licenses Marine Fuels and Heron Marine in 2018 and 2019 respectively.
Aegean, which now operates as Minerva, is a wholly owned unit of global energy trader Mercuria and Heron Marine is a subsidiary of rival Trafigura, while SA Marine Fuels is majority owned by Oryx Energies.
Trafigura, Minerva and Oryx Energies did not immediately respond to requests for comment.
A moratorium on new licenses, in place since August 2019, will not be lifted until an environmental impact assessment has been carried out by the port authorities. This assessment is expected next year, said a SAMSA official.
The Nelson Mandela University study used data from the Ship Identification Tool to estimate underwater ship noise as a proxy for ambient underwater noise in the area.
In 2019, oil penguins were discovered in Algoa Bay after an oil spill from ship’s bunkering and conservationists called for bunkering to be banned in the bay.
Mr Pichegru said penguins in Les Sainte-Croix were already struggling to reproduce due to various problems, including industrial fishing for rare prey.
“Refueling didn’t kill all the penguins, it just flipped the whole ecology and then the penguins couldn’t cope with that,” she said.