A recent study from Curtin University, in collaboration with researchers from Europe and North America, highlights the need to take underwater noise created by commercial and recreational ship traffic into consideration when planning marine spatial environments.
In a paper released by the Marine Pollution Bulletin, Associate Professor Christine Erbe, Director of the Centre for Marine Science and Technology, says substantial potential exists for area-based management to reduce exposure of animals to chronic ocean noise.
“A core task in endangered species conservation is to identify important habitats and manage human activities to mitigate threats,” Associate Professor Erbe said.
“Many marine animals rely on acoustics for communication, reproduction, navigation, foraging and sensing their environment.”
The study introduces the concept of ‘opportunity sites’ – important habitats that experience low ship noise – and suggests that measures are put in place to protect these sites in the future.
“Incorporating noise into spatial planning, such as for critical habitat designation or marine protected areas, may improve ecological integrity and promote ecological resilience to withstand additional stressors,” Associate Professor Erbe said.
Associate Professor Erbe and her colleagues suggest that ‘no-go’ zones for boats and fishing should be substantially larger than existing marine reserves allow. Sound travels very well and a long way under water – therefore a no-go zone for boats that is the same size as the area protected is not large enough when the acoustic parameters are taken into account.
By mapping ship traffic in British Columbia, Canada, the team modelled underwater noise from all vessels over the period of one year. They computed maps of ship noise, validated the map at 12 sites and then ‘filtered’ the ship noise with the hearing curves (audiograms) of the 11 marine mammal species (such as whales, seals and dolphins) which make British Columbia their habitat, resulting in a noise map that was unique and meaningful to each species.
The study looked at areas where there is overlap – many animals and much noise – and areas where there is no overlap – many animals but no noise.
“The areas of overlap are ‘sites of risk’, where you might eventually see long-term impacts from shipping noise,” Associate Professor Erbe said.
“The areas without overlap are ‘sites of opportunity’ which should equally be included in marine spatial planning.
“Marine spatial planning often focuses on the risk sites, where things have already gone wrong and we try to implement measures to fix things and improve the disturbed or deteriorated environment.
‘We don’t often take a step back and look at the opportunity sites, however as this study shows, it could prove well worth doing so for the future survival and success of many marine animal habitats.”