Noisy seas are driving our penguins away
Underwater noise generated by humans is causing damage to hearing, killing fish eggs and making penguins flee
Potentially-deafening blasts of underwater noise from the oil and gas exploration industry drove South African penguins away from their feeding grounds, scientists have found after a five-year study.
Published in the journal Scientific Reports, the new study suggests that endangered African penguins deliberately move away from underwater sound blasts generated during seismic surveys – either because they are traumatised by the noise, or because the fish they are chasing are fleeing from the noise.
Lead author Dr Lorien Pichegru of the University of Cape Town notes that sound travels about five times faster in water than through air, while other studies suggest that high-decibel noise from seismic surveys can be detected up to 75 km away in shallow water or up to 4 000 km away in very deep water.
Pichegru and fellow researchers from the Nelson Mandela University based their findings on the feeding movements of penguins in Algoa Bay, Port Elizabeth – home to nearly half the remaining global population of African penguins.African penguins were recently reclassified as endangered after evidence that the population level of this flightless sea bird species has dropped by nearly 70% over the last 10 years.
Pichegru and her colleagues Reason Nyengera, Alistair McInnes and Dr Pierre Pistorius said: “To our knowledge, this is the first record of avoidance behaviour by a seabird to sound generated by (human) activities at sea.”
The research – with sponsorship from the Jersey-based oil and gas company NewAge – adds to a growing body of research linking underwater seismic surveys by the oil and gas industry to harmful and potentially fatal side effects for a wide variety of marine creatures, from giant whales to tiny plankton species.
For example, Pichegru and her colleagues point to previous studies suggesting that seismic noise can damage the hearing and possibly kill certain large sea mammals, damage the organs and tissue of some fish species and also kill fish eggs and zooplankton close to seismic survey operations.Similar fears were voiced two months ago by Ezemvelo KZN Wildlife marine ecologist Dr Jennifer Olbers, who questioned whether record levels of whale and dolphin deaths on the KwaZulu-Natal coast during 2016 were linked with oil and gas seismic surveys during that year.
During seismic surveys, underwater airguns towed by ships blast sound waves of up to 250 decibels into the water every 10 to 15 seconds for 24 hours a day to help build up sonar images of seabed formations that may contain oil and gas.
The latest report by Pichegru and her colleagues follows a lengthy study on the feeding movements of penguins at St Croix Island and Bird Island in Algoa Bay – including a 2D seismic survey conducted off the bay during February and March 2013 covering a sea area of almost 6 700km.The researchers found that penguins from St Croix (tracked by means of GPS recorders) began to forage significantly further away from their normal feeding grounds during the seismic survey – and then reverted to normal behaviour as soon as the seismic blasts stopped.
“The exposure to intense sounds, such as shooting of airguns during seismic operations, can adversely affect the hearing capacity of marine mammals and other species, either temporarily or permanently,” the researchers noted.
While most bird and many fish species were able to regenerate lost or damaged sensory cells in their ears, “we cannot rule out potential longer-term impacts on their hearing ability”.
They cautioned that rapid expansion of human exploration of the sea for minerals, petroleum and other resources in recent decades has increased underwater noise levels significantly – posing significant new threats to species that have evolved to rely on sound-based cues to catch their prey, dodge predators or to attract breeding mates.“In addition to over-fishing, habitat destruction and chemical pollution, underwater noise pollution is now recognised as a significant threat to marine wildlife,” the researchers warned.
Though oil and gas exploration companies have adopted a range of measures to mitigate the potentially negative impact of seismic surveys – including restrictions on surveys during the peak whale migration season – Pichegru and her colleagues conclude that there is a crucial need for further studies on the impacts of loud noise on marine animals and seabirds.
NewAge, which helped to sponsor the research project, is no longer pursuing oil and gas exploration off the South African coast. Responding to queries on the penguin study, a spokesman in London said New Age had relinquished the permit it previously held for oil and gas exploration off Algoa Bay.
“We are very pleased that (this) research, and our funding of the research, is helping to conserve this endangered species. We firmly believe that any companies undertaking future seismic activity should be cognisant of its impact on African Penguin colonies and look to mitigate impacts accordingly.
“NewAge always acts in an environmentally responsible manner and, ahead of the seismic activity mentioned in the article, we worked closely with the Petroleum Agency of South Africa (Pasa) and environmental experts to develop a detailed plan to avoid impacts to wildlife. This environmental plan was made widely available to interest groups by public consultation, at the time.”