Tagged: acoustics

Behavioural and physiological effects of anthropogenic sound on cetaceans

R. Lung \ Oceans First, Issue 1, 2014, pgs. 12-19.

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Abstract:

Studies show increasingly negative effects associated with anthropogenic sound and human disturbance. These negative effects are both behavioural and physiological. The chronic activation of the short-term stress response as a result of increased ship noise potentially has detrimental effects regarding growth, reproduction, immune function, and digestion. Methods to acquire data involving behaviour are mainly observational. To monitor acoustic behaviour, hydrophones are used. The behaviour of cetacean species is altered in the presence of human disturbances such as marine construction, sonar, and ship noise. Their vocalizations are also affected; differing in length, overall presence, and frequency. Mass strandings have occurred as a result of active naval sonar exposure. Naval sonar administers frequencies similar to those of beaked whales, often resulting in acoustic masking. To examine sustained injuries, post-mortem internal examinations are conducted. The sonar signals can have fatal effects, including hemorrhage in multiple organs, gas and fat embolism, and bubble lesions formed as a result of the supersaturation of nitrogen gas within tissues. Future research will enable the determining of more long term effects in relation to anthropogenic sound effects.

An acoustical analysis of the variability of the diel vertical migration of zooplankton in Saanich Inlet

H. Boddy \ Oceans First, Issue 1, 2014, pgs. 1-11.

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Abstract:

The diel vertical migration of zooplankton exhibits variation due to a number of environmental factors. In this research, active sonar technology was used to remotely observe and map zooplankton behaviour in Saanich Inlet, off of Vancouver Island. A zooplankton acoustic profiler (ZAP) was placed 100m below the surface on the Venus Instrument Platform (VIP) where it continuously emitted ~300 microsecond pulses of 200 kHz frequency sound. The acoustic images from the ZAP were then used to attempt to understand zooplankton’s migratory trends. It was noted that daylight influenced migration length, temperature and oxygen affected zooplankton abundance, and the mixing of oceanic pycnoclines caused a uniform distribution of zooplankton with depth. Overall, the results from this study suggested that zooplankton migrations vary as a result of multiple environmental factors, but further study is needed to understand the implications of these results.