Acoustic trauma can be fatal for whales and dolphins. It can cause deafness; hinder their reproduction; fatally compromise communication between mothers and calves; disrupt breeding, nursing and immune system functions; hinder the ability to find prey; and disrupt behavioural and migratory patterns.
Sonar can cause the lungs and ears of whales to haemorrhage, causing dreadful deaths. But protocols to identify acoustic trauma as the cause of death in animals are virtually non-existent in Australia.
Zooplankton, which form the base of the food chain and are vital nutrition for whales and numerous invertebrates such as oysters and shrimp, are highly vulnerable to seismic blasts. One study showed that one blast, even at a lower level than those typically used in oil and gas prospecting operations, could destroy half the zooplankton in the area. Up to 95% of certain species died.
Death by a thousand cuts
Dr Sylvia Earle, a renowned marine biologist, describes undersea noise pollution as like “the death of a thousand cuts”.
An offshore gas drilling project proposed by Advent Energy involving plans to drill for gas in an area covering 4500 square kilometres of ocean from Port Stephens to the central coast of NSW is just the latest project to raise major concerns over man-made ocean noise.
Seismic surveys typically involve ships towing an air gun that fires a pulse of sound every 8-12 seconds. Noise from a single airgun survey can blanket an area of more than 300,000 square kilometres, raising background noise levels 100-fold continuously for weeks or even months.
Christopher Clark, a marine bioacoustics expert and retired director of the Bioacoustic Research Program at Cornell University, describes the cumulative impacts suffered by marine species.
“Imagine a space ship is over your village and it’s sending explosions down every 10 seconds driving everyone crazy. The choice is either you leave or die.
“The use of sound for communication and detection in the marine environment is important for survival of marine animals. Marine animals depend on their hearing sensitivity to retain cohesion in groups, for detection of predators, for sensing their physical and biological environment.
In light of this it is concerning that the federal Environment Department watered down its strategic assessment of the effects of noise pollution on the marine environment.
The department’s draft Great Barrier Reef strategic assessment stated categorically that:
“There has been no comprehensive study of the effect of man-made noise on GBR species.”
However, the final strategic assessment was rewritten to state only that: “There are no specific standards for the range of noise pollution affecting the GBR species.”
And while the final assessment stated that there was a national policy addressing the acoustic impacts of seismic surveys on whales, the only whale study it refers to is dated 2008, more than 13 years ago.
However, the assessment does go on to say that:
“There is an urgent need for a greater understanding of the ecological impacts of noise within the region and for guidance on measures to avoid or mitigate these impacts.”
In 2019, the Senate referred an inquiry into the impact of seismic testing on fisheries and the marine environment to the Environment and Communications Reference Committee. The Committee has requested an extension to 10 June, 2021 to allow it to consider the evidence received.
However, the inquiry is limited to seismic testing. The terms of reference do not cover all sources of underwater noise generated in Australia.
Not only are whales and dolphins at risk from noise but virtually all marine species are exposed. Underwater noise can travel for many hundreds of kilometres depending on the geoacoustic parameters, which include tides, wind, seabed conditions, thermoclines and so on. Ocean acidification allows noise to travel further.
Noise a major source of stress
A 2006 Austrian study confirmed that exposure to underwater noise pollution was a major source of stress for freshwater fish. Ship noise can increase the secretion of stress hormones in fish by up to 120% in comparison with a no-noise situation.
A 2020 study by researchers at Cardiff University showed that fish stressed by noise are less able to fight off disease, and that prolonged exposure can lead to early death.
OceanCare, a non-governmental organisation based in Bern, Switzerland, released in May a review of 115 studies done mainly in the 1990s and 2000s, showing the effects of ocean noise on 66 species of fish and 36 kinds of invertebrates.
One study showed that one seismic blast, even at a lower level than those typically used in oil and gas prospecting operations, could destroy half the zooplankton in the area. Up to 95% of certain species died.
In evidence to the Senate Standing Committee Associate Professor Robert McCauley, an expert in the field, stated:
“There is documented evidence that marine seismic survey operations using air gun sources may: 1) seriously impact plankton; 2) physiologically compromise scallops; 3) impair and damage lobster; impact and potentially damage cephalopods; and 5) cause hearing damage and behavioural responses in fish.”
A marine scientist summed up Australia’s position in his submission to the Senate Inquiry thus:
“I am appalled at the lack of scientific rigour by the fossil fuel industry when it comes to oil and gas exploration. If the Australian public were aware of the potential impacts there would be much stronger resistance and objection.
“Indeed, were the community to be consulted at all, they would be united in opposition.”
In 2013, the Commonwealth government made an election commitment to streamline environmental management regulation for offshore petroleum and greenhouse gas activities by making the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) the sole designated assessor for offshore environmental management of petroleum activities undertaken in its jurisdiction, Commonwealth waters.
NOPSEMA’s board is comprised almost entirely of members who have links to the oil and gas industry. There are no conservation organisations or scientists with expertise in the marine environment on the board.
Moreover, its powers are weak. Enforcement action includes issuing improvement notices, giving directions, requesting a revision or withdrawing acceptance of an environment plan and prosecution.
Drilling undertaken in state or territory waters is also not covered by any legislation focused on underwater noise, or marine pollution caused by noise.