Read the texts and match the headings to them. There is one that you do not need to use.
Write one number in each gap.
The consequences of ocean noise pollution
The sources of ocean noise pollution
The importance of sounds for creatures
The existing solution
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Many marine organisms rely on their ability to hear for their survival. Sound is a highly efficient means of communication underwater and is the primary way that many marine species use to understand their environment. Many aquatic animals use sound to find prey, locate mates and offspring, avoid predators, guide their navigation and locate habitat, as well as to listen and communicate with each other.
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Over the last century, human activities have increased along our coasts, offshore, and deep ocean environments. These rising noise levels can negatively impact ocean animals and ecosystems. Higher noise levels can reduce the ability of animals to communicate with potential mates, other group members, their offspring, or feeding partners. Noise can also reduce an ocean animal's ability to hear environmental cues that are vital for survival, including those key to avoiding predators, finding food, and navigating to preferred habitats.
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One of the most widespread types of underwater noise pollution is that generated by shipping — and in particular, the noise generated by the blades of a vessel's propellers. To solve that problem, more efficiently designed propellers are available. Danish shipping tycoons Maersk have installed upgrades on 11 of its fleet, noting that acoustic output was reduced by 75%. However, the problem lies in the fact that Maersk spent over $100 million to retrofit their fleet.