In an attempt to get a clearer picture of the UK’s underwater soundscape, a study by the University of Exeter has identified how potentially threatening marine noise pollution can be for a variety of common fish species.
Investigations into the effects of noise pollution on large marine mammals, such as beaked whales, have shown how gruesomely damaging it can be; often resulting in inner ear, lung or brain damage caused by acoustic pressure. However, it is often overlooked at how this underwater clamour affects some of our smaller fish species such as cod and haddock. Similar to the effects on marine mammals, noise pollution can interrupt or drown out the complex acoustic communication that occurs between fish.
That’s right, fish talk to one another! Unlike whales and dolphins that use their voice box to produce sound, many species of fish use their swim bladder to make a variety of noises from grunts to clicks. This form of communication is important for activities such as mapping out territories, creating predator warnings and also play a key role in complex mating rituals. This is especially relevant for species such as cod. In order for a female to release her eggs to be fertilised, a male counterpart must first woo her by completing a short series of specific noises. If not completed correctly, the female will reject her partner and seek another. This is where marine noise pollution has the most direct and threatening effect on populations of fish. If a male has his "song" interrupted, or a female becomes confused amongst the racket produced by anthropogenic sources, entire reproductive cycles can be compromised.
Investigations by biosciences lecturer Steve Simpson and his associates are using hydrophones to map level of noise pollution and create soundscapes of the UK’s surrounding oceans. The study aims to help us understand the effects of anthropogenic noise specific to the UK, and how it is affecting our local species. So what is creating such a clamour? The large majority of anthropogenic noise in the ocean comes from commercial shipping and fishing vessels. However activities such as Jet Ski traffic near beaches and fossil fuel exploration mechanism (sonar, air guns etc.) also has significant effects on marine life. The UK Marine Noise Registry was created this year in order to record human activities that produce potentially harmful levels of noise. Data can be input into the registry by anyone, and aims to create annual maps of noise pollution that will allow us to closely monitor the effects on marine life.
The potential affects on species of economic worth such as haddock and cod may see a more rapid response from stakeholders in the fishing and shipping industry, as there seems to be a disconnection regarding species of little financial value being affected, such as cetaceans.
UK Marine Noise Registry: http://jncc.defra.gov.uk/page-7070
Boat Noise Pollution Disrupts Orientiation Behaviour in Coral Reef Fish: http://www.int-res.com/abstracts/meps/v485/p295-300/