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Behavior

Eavesdropping prawns get more than they bargained for

The paper:

Filiciotto, F., Vazzana, M., Celi, M., Maccarrone, V., Ceraulo, M., Buffa, G., Arizza, V., de Vincenzi, G., Grammauta, R., Mazzola, S., Buscaino, G., 2016. Underwater noise from boats: Measurement of its influence on the behaviour and biochemistry of the common prawn (Palaemon serratus, Pennant 1777). J. Exp. Mar. Bio. Ecol. 478, 24–33. doi:10.1016/j.jembe.2016.01.014

The words prawn and shrimp can be used interchangeably. Credit: Jim Olive. U.S. Nat. Archives: 412-DA-1412

The words prawn and shrimp can be used interchangeably. Credit: Jim Olive. U.S. Nat. Archives: 412-DA-1412

 

Background

Humans can be LOUD! We scare off wildlife just by chatting when we are out for a walk. Imagine when big machines or vehicles are involved, the sound alone can change an ecosystem. Noise is even considered a pollutant by the United Nations Convention on the Law of the Sea. The ocean is not a quiet place naturally with a lot of marine animals using sound to communicate or find their way around but human activity has changed the soundscape in a big way. Commercial shipping is very widespread and the huge container ships are making a lot of noise below the surface.

Crustaceans are some of the most popular seafood including lobsters, crabs, and shrimp but we don’t know much about how all this noise might be effecting their health and survival. Crustaceans can suffer physiological and behavioral changes when stressed and though it may not be obvious due to the lack of ears they are able to hear. This study investigated the impact of simulated noise pollution on the common prawn (Palaemon serratus).

 

Methods

Researchers working in the Mediterranean, an area with high boat traffic, caught prawns off the coast of Italy and acclimated them to a lab environment for a month. For the experiments prawns were randomly divided into a control or noisy treatment. After thirty minutes of silence the prawns were subjected to thirty minutes of simulated boat noise similar to what would be heard at a busy port. The boat noise was a mixture of recordings of nine different types of boats near a harbor. The behavior of the prawns was videoed and compared to the level of sound being played at the time. The researchers looked for changes in behavior and recorded when the prawns showed a startle response, encountered each other, walked, rested, spent time in or out of a shelter, and tail flips (moving them quickly to a new location). Biochemical analyses were also performed on the prawns after the experiment.

Big container shrimp moving across a lot of marine habitat. Credit: NOAA

Big container shrimp moving across a lot of marine habitat. Credit: NOAA

Results and Significance

Prawns that had to put up with thirty minutes of boat noise showed changes in behavior and physiology. These prawns had fewer encounters with each other and spent more time outside of a shelter. They did not, however, show startle response indicators or tail flips which indicates that an immediate, quick response was not occurring. After noise exposure there was an increase in stress proteins. The impacts of the noise may be more of an issue with sustained stress from noise.

Although conditions in the wild are very different from how noise might be experienced in a small, enclosed tank this study helps set the groundwork for future research noise pollution. We also don’t know what the implication of having stressed crustaceans in our seas. We hear a lot more about other types of pollution but increased noise could be negatively effecting marine organism as well. A lot of work is left to do but now that we know the seas have ears it might be time to watch what we say or at least how loud we say it.

Sarah Giltz
I am a doctoral candidate in Ecology and Evolutionary Biology at Tulane University. My research focuses on the larval dispersal and development of the blue crab in the Gulf of Mexico.

When not concerning myself with the plight of tiny crustaceans I can be found enjoying life in New Orleans with all the costumes, food, and music that entails.

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