Noise Pollution

Now this one surprised me at first, as I had never come across it before. However, it appears that noise from ocean-based anthropogenic activities is having an effect on marine species. Indeed, both literature and non-academic sources list shipping, activities from the oil and gas industries and those from the military as the most common sources of noise pollution in our oceans (Weilgart 2007; International Fund for Animal Welfare).

Noise pollution in our oceans is of particular concern to cetaceans (whales, dolphins and porpoises) because they rely on their sense of sound more than any other sense (Weilgart 2007) for communication, navigation and the monitoring of their surroundings (Monterey Institute). Because noise travels a lot faster in water, it is has a far greater reach than it does when it travels through air (Smita 2001), suggesting that its effects can be felt by marine species even when they are not found in the vicinity of the point of origin. Suggested effects of noise pollution on cetaceans include disorientation, leading to stranding and moralities (Weilgart 2007).

However, ceteaceans may not be the only ones affected. A paper by Slabbekoorn et al. (2010) called for more studies to be carried out on the effects of increased marine noise on fishes. Although it is known that the hearing ranges of fishes do overlap with the frequencies of anthropogenic-induced marine noise [Figure 1], it is unsure what the ecological implications are of long-term exposure to such noises (Slabbekoorn et al. 2010).

Figure 1. The hearing ranges of a sample of fish species (red bars; from top: European eel, Atlantic cod and goldfish) and mammalian species (blue bars; from top: California sea lion, bottlenose dolphin and fin whale). The grey block represents the range of anthropogenic noise, while the three grey bars at the bottom indicate the range for low, mid and high-frequency sonar (Slabbekoorn et al. 2010)

Increases in noise levels in our oceans may be already having a detrimental effect on marine species, but it is only going to get worse with climate change. It appears that sound travels faster in warmer water. Whilst it is known that ocean acidification is a cause of the rise in atmospheric carbon dioxide, according to Hester et al. (2008), this will lead to noisier oceans as sea temperatures continue to rise!

1 comment:

  1. This also surprised me, as it is not immediately obvious but makes so much sense! Its worrying to think that anthropogenic activities go way beyond the noticeable physical effects such as the previously addressed entanglement. Do you know if there has been any research done into adaptations for increased tolerance of noise by particular species?