Effects of anthropogenic noise on the behaviour of juvenile lobsters (Homarus gammarus)
The German European lobster population of Homarus gammarus has been in decline since the 1960s and its recovery efforts with reared juveniles have yet to produce good results. Juveniles are one of the most vulnerable life stages as they depend on the availability of hard substrate that serves them a...
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| Format: | Thesis |
| Language: | unknown |
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2020
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| Online Access: | https://epic.awi.de/id/eprint/54038/ https://epic.awi.de/id/eprint/54038/1/Bachelorarbeit_Biologie_1-Fach_Soeren_Scholz.pdf https://hdl.handle.net/10013/epic.bf40918d-03f7-4fd7-993e-80d8f35c0d57 |
| Summary: | The German European lobster population of Homarus gammarus has been in decline since the 1960s and its recovery efforts with reared juveniles have yet to produce good results. Juveniles are one of the most vulnerable life stages as they depend on the availability of hard substrate that serves them as shelter, like rocks and boulders. Since the substrate in the German North Sea consists mostly of soft substrate like sand and mud, one viable habitat is the rocky island Helgoland. An increase of possible habitats could therefore increase the survivability of lobsters, wild and reared all together. Two of those new possible habitats are riffs constructed from the European oyster Ostrea edulis, with restoration attempts for rehabilitation in the North Sea already in progress. The other are the foundation of newly constructed Wind Farms, which often consists of rocks and boulders that envelope the foundation on the seabed. While this could lead to a surplus in new habitats due to the construction of several new Wind Farms over the next years, little is known about the possible effects’ exposure to the low-frequency noise produced by the Wind Turbines operation. To understand habitat selection and anti-predator responses lobsters might face in these underwater structures, the present study aimed to test noise and predator effects on shelter preference and behavioural responses in a full factorial design. Juvenile lobsters (n = 104; mean and standard deviation total length of 12,29 ± 0,97 mm) were exposed to one of the four conditions (control, noise, predator, and noise + predator) for three hours during nighttime (when they are most active), and the time spend on predetermined behaviours was analysed from video records (20 min were analysed). Measured at the beginning and at the end of the exposure was the preferred shelter selection, lobsters selected the rocks over the oyster shells most of the time, which is supported by the literature. However, as oyster reefs represent much more complex habitats than the stacked ... |
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