By Kirsty McLaughlin @BlackNarcissus1
You are just about to tuck into a delicious meal, when all of a sudden, road works begin outside the restaurant. Initially you may stop eating as you are distracted or perhaps stressed out by the annoying din. However, what if the racket continues? Would you continue to be distracted, letting your food go cold and your hunger unsated? Or, after a while would you get used to the noise and continue eating, giving into your rumbling stomach?
During my PhD I posed similar questions to fish. I wanted to discover the effects of anthropogenic noise on convict cichlid behaviour. Noise is a major global pollutant and is only set to continue increasing, in both terrestrial and aquatic environments. I examined the effects of noise on foraging, movement, and reproductive behaviour, exposing fish to noise for short and long-term periods. First I asked; does noise affect the foraging behaviour of fish?
My initial experiment exposed fish to a few minutes of ship engine noise. I found that fewer fish foraged during noise than during a control period (McLaughlin and Kunc 2015). Noise caused fish to stop eating, perhaps distracting them or, as is suggested by analysis of their movement throughout the tank, causing them to ‘hide’ from the noise (McLaughlin and Kunc 2015). Therefore, the short-term reaction of fish to noise appears to be to stop eating and even hide under the table.
But what happens if the noise continues beyond just a few minutes? To address this I analysed the foraging behaviour of fish exposed to noise for hours at a time. I found, that during long-term noise exposure, the foraging behaviour of fish was not negatively affected. This suggests that the effect of noise on foraging is transient. However, it would be wrong to assume that this result means that long term noise does not negatively affect fish. Examination of the effect of noise on other behaviours during my PhD, such as those involved in reproduction, suggest otherwise. I hope to showcase these results in future blog posts.
With regards to foraging, after a while fish seem to either get used to the noise, or give into their rumbling stomachs and continue eating. Perhaps like me, they are unwilling to let a little noise ruin a perfectly good meal!
Reference: McLaughlin & Kunc (2015) Changes in the acoustic environment alter the foraging and sheltering behaviour of the cichlid Amatitlania nigrofasciata. Behavioural processes, 116, 75-79.