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The dark side of marine renewable energy developments

Marine renewable energy developments may disturb marine mammals and seabirds. Scientists are researching solutions to minimise negative impacts.

In response to the growing concerns regarding energy security and climate change, many countries across the globe are investing in the development of marine renewable energy installations. These include offshore wind farms as well as wave and tidal devices, the so-called wet renewables. The benefits of these investments for our society are indisputable, but scientists and conservationists have cautioned towards possible detrimental consequences on marine mammal and seabird populations and are currently working on developing appropriate solutions to mitigate these impacts.

The construction of marine renewable energy plants generates loud noise, mainly as a result of fixing these structures to the seafloor. Close to the source, noise can cause temporary or permanent damage to the animals’ hearing system or mask their vocalisations. Behavioural or physiological responses may also occur. For example, marine mammals have been documented to move away from disturbed sites. On the other hand animals that are not displaced can experience increased levels of stress or changes in their feeding activity. Later, when these installations become operational, risks include direct collision resulting in injury or death or, again, disturbance from noise. However, positive effects have also been suggested: fisheries cannot access marine renewable energy sites and the structures placed in the sea can act as artificial reefs. This might promote biodiversity and, ultimately, benefit top predators.

 

offshore wind turbine
Construction of a turbine in the Ormonde offshore wind farm in England © Anthony West/Corbis

 

Cutting-edge technologies are currently being used to study the behavior of the animals around the devices. These include tracking systems either attached to the animals or on the installations. Alternative ways to fix them to the seafloor and mitigation measures to reduce emitted noise also exist. However, the biggest challenge remains understanding how observed changes in behavior translate into long-term effects on the populations. Conserving wildlife populations is the main target of existing legislation (for example the European Habitats and Birds Directives), and behaviour is not necessarily a good indication of the severity of disturbance. For example, marine mammals may fail to react to noise when an area is particularly important to them, but exposure could nonetheless result in a negative impact. Advanced statistical modelling is required to bridge this gap and anticipate any long-term effect at a population level.

 

Viable alternatives to fossil fuels need to be implemented quickly if we want to contrast climate change. However, this should be achieved without causing additional harm to our oceans. Intense research efforts are ongoing to find novel solutions that will allow us to evaluate and minimise the negative effects of marine energy developments and preserve the status of marine wildlife populations.

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