Effects (2/2): Wildlife and Noise Pollution

In the primary school science syllabus, students learn about six main characteristics of living things that differentiate them from non-living. I’ve outlined them below.

1. Living things need air, food and water to survive
2. Living things respond to changes
3. Living things reproduce
4. Living things grow
5. Living things can move by themselves
6. Living things die

How is this related to noise pollution? There are multiple articles, research and videos that have sought to uncover how humans have affected wildlife. Noise pollution has impacted the above, where animals are responding to increasing noise levels or noise levels in areas that were previously quiet.

Changing behaviour

Here are some examples of the ways noise pollution impacts species of wildlife. Squid, fish, bats and crustaceans are just some of the animals that have changed their behaviour in response to anthropogenic noise sources. While adaptivity and the ability to respond to one’s surroundings are key for survival, this only holds if animals are given enough time to change and if the conditions before and after the change are not too extreme. If noise levels continue to rise, there might be other implications for the health and behaviour of wildlife.

Squids are adjusting to industrial pile drivers, equipment that drives support into the seabed for construction projects. Researcher Ian Jones recorded pile-driving sounds to 16 different squids in a tank, then repeated the experiment 24 hours later to see if they got used to the noise (Kingdon, 2020). Each time, the squids squirt out jets of ink, change colour and swim away when subjected to the loud hammering of a pile driver. This adaptability could compromise their ability to survive as they are less vigilant to actual threats (Kingdon, 2020). Most research on noise pollution explores whales and fish, so this is a new area that would expand our understanding of increased noise levels of wildlife. While cephalopods do not make sounds and do not have ears, they have an organ called a statocyst that helps them balance, similar to the function of a human’s inner ear. This organ also detects vibrations from noise, thus increased noise levels might be disruptive to cephalopods (Kingdon, 2020).

Boat motors are speeding up metabolism in fish embryos. A study conducted by researchers in Australia observed the embryos of two species of damselfish common in Australian coral reefs – spiny chromis and the red and black anemonefish (Fakan and McCormick, 2019). The research followed individuals as egg-bound embryos and then as freshly hatched larvae. The eggs were exposed to one of two sound treatments – the control group listened to a recording of reef sounds, while the experimental group listened to the same recording with clips of a two-stroke engine that is mechanically similar to the motor that drives a chainsaw (Currin, 2019).

They discovered that the embryo hearts in the experimental group beat 10% faster than the control group. The spiny chromises listening to boat noise recordings hatched about 5% larger than those under ambient noise, with eyes about 9% larger. While it may seem that larger larvae have a better chance of survival, these larger bodies came at the expense of energy reserves (Currin, 2019).

Researchers think that the faster growth is prompted by the development of the embryos’ sensory organs before their stress response systems. This creates a window of time during their first days when they can perceive and identify threats, but cannot respond to them. However, it is not clear whether any of these changes are detrimental to the fish, though it is probable that these alterations may influence the fish at their later life stages (Fakan and McCormick, 2019).

On land, bats have also been discovered to change their calls to cope with anthropogenic noise pollution. In a study conducted in natural gas fields in the San Juan Basin in Mexico, researchers discovered that Brazilian free-tailed bats spent 40% less time near compressors. Bats near the compressors also altered their cries to a narrowed acoustic range near the machinery, while bats with higher-pitched calls distinct from the noise generated by compressors did not show changes (Cornwall, 2014). In 2015, research also revealed that noise from human activity can impair the foraging activity of Daubenton’s bats (Luo, Siemers and Koselj, 2015). Bats that were exposed to traffic noise were less able to catch their prey, and they were less active when it came to foraging (Luo, Siemers and Koselj, 2015).

As renewable sources of energy become a more viable option, wave power and tidal power are technologies that have become more popular. In 2015, marine biologist Matt Pine led a study to examine how noise pollution might affect marine life in Kaipara Harbour, New Zealand as tidal power generators were considered for installation there (Treacy, 2015). In the life cycle of crustaceans, the metamorphosis stage marks a loss of ability to eat and gain of ability to swim. Here, they require cues from the shoreline to reach the beach and complete their transition into adulthood. With tidal turbines in estuaries, natural sounds of the coast could be masked.

Of course, there are many more ways that wildlife has responded to the encroachment of humans in the form of a noisier world, and these continue to be areas of research for scientists. In the final section of this blog, we will be exploring how noise pollution can be addressed through behavioural changes.

 

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