The number of African penguins on Saint Croix island in Algoa Bay has declined since South Africa started to allow ships to refuel at sea, a process known as bunkering, a new study published in Science of the Total Environment journal found.
Saint Croix Island is the largest of three islands in Algoa Bay. The islands are critical to sea bird populations, including the endangered African penguin. The are only 41,700 mature individuals left in the world, according to the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species.
Lorien Pichegru, director of the Coastal and Marine Research Institute at Nelson Mandela University, which led the study, said that there were 8500 breeding pairs at Saint Croix in 2016. The number declined by 85% to 1200 breeding pairs of African penguins in 2022.
Algoa Bay is a marine biodiversity hotspot, where the largest population of endangered African Penguins live, as well as other seabirds, whales, dolphins, and seals.
It’s situated in a busy shipping lane along South Africa’s east coast. Six years ago, the government allowed bunkering, which makes so much noise it scared off the penguins. Currently, Algoa Bay is one of the noisiest bays in the world.
Pichegru said that since refuelling at sea began, the noise levels, which were already huge, doubled. The new study is the first to analyse the impact of maritime traffic noise pollution on seabirds, and the consequence of offshore bunkering activities on underwater noise levels, researchers said.
Scientists have previously found that high noise levels affect marine animals’ ability to communicate, find and catch prey, or navigate properly.
Pichegru said penguins in the Saint Croix islands were already struggling to breed due to various challenges, including industrial fishing.
“Bunkering did not kill all the penguins, it was just the thing that made the whole ecology tip over, and then the penguins couldn’t cope with that,” she said, adding that she counted dead birds on the beach of the bay every month.
