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Safe and sound: A: Soundscapes and seabream, B: Sound and survival

Holmes, Roxanne (2019) BION03 20182
Degree Projects in Biology
Abstract
Underwater soundscapes provide valuable information for the survival of fishes. These auditory cues create “acoustic daylight” to help guide orientation to coastal areas for settlement and govern movements and between habitats in post-settlement recruits. In the temperate French Mediterranean Sea, acoustic recordings in addition to Underwater Visual Census (UVC) of the white seabream (Diplodus sargus) show that the total abundance of juveniles is significantly associated with areas of a high root-mean-squared sound pressure level (SPLrms) in the lower frequency range (1 Hz –5 kHz), especially within the bandwidth associated with urchin sounds (700 Hz –2 kHz). The Acoustic Complexity Index, Acoustic Richness, and the number of snaps... (More)
Underwater soundscapes provide valuable information for the survival of fishes. These auditory cues create “acoustic daylight” to help guide orientation to coastal areas for settlement and govern movements and between habitats in post-settlement recruits. In the temperate French Mediterranean Sea, acoustic recordings in addition to Underwater Visual Census (UVC) of the white seabream (Diplodus sargus) show that the total abundance of juveniles is significantly associated with areas of a high root-mean-squared sound pressure level (SPLrms) in the lower frequency range (1 Hz –5 kHz), especially within the bandwidth associated with urchin sounds (700 Hz –2 kHz). The Acoustic Complexity Index, Acoustic Richness, and the number of snaps produced by snapping shrimp were not found to have any significant association with the total abundance of seabream recruits. Size of recruits was found to play a role in the relationship between abundance and soundscape, as significant relationships were only found between small recruits (40–50 mm) and not in larger recruits (60–70 mm), who may have settled earlier in the season. Benthic habitat surveys revealed that SPLrms of various bandwidths was significantly correlated with the benthic substrate and may be the most reliable indicator in habitat selection by recruits postsettlement. The strong links between the soundscape and the abundance of recruits suggests that the use of acoustic data may be a valuable addition to the long term monitoring of D. sargus populations and help with predicting and protecting potential high density nursery areas over time. (Less)
Popular Abstract
Juvenile fish abundance is associated with the ambient soundscape but motorboats could disturb these soundscapes and reduce anti-predator behaviour and survival


Sound moves more than 4 times faster in water than air. This makes sound a perfect modality for aquatic organisms to sense their environment. Juvenile fishes use sound to help them find coral reefs and choose suitable habitats to live in. Sound is also important in reproduction, communication and avoiding predators.

In the French Mediterranean Sea, taking sound recordings and surveying the abundance of juvenile white seabream (Diplodus sargus), a commercially important fish species, revealed that the juvenile fishes were found more often in areas with a higher sound... (More)
Juvenile fish abundance is associated with the ambient soundscape but motorboats could disturb these soundscapes and reduce anti-predator behaviour and survival


Sound moves more than 4 times faster in water than air. This makes sound a perfect modality for aquatic organisms to sense their environment. Juvenile fishes use sound to help them find coral reefs and choose suitable habitats to live in. Sound is also important in reproduction, communication and avoiding predators.

In the French Mediterranean Sea, taking sound recordings and surveying the abundance of juvenile white seabream (Diplodus sargus), a commercially important fish species, revealed that the juvenile fishes were found more often in areas with a higher sound intensity, specifically in the bandwidth created by urchins. While looking only at the habitat, we were unable to determine any patterns in their distribution. This suggests that these young fishes may choose their habitat based on the natural soundscape rather than the habitat itself and that using sound recordings may give a lot more information in ecological surveys than simple observations provide.

As the planet becomes more populated and human noise pollutes our seas, these natural soundscapes are being disturbed and juvenile fishes are no longer able to use these cues for important survival behaviours. Understanding the effects of this noise on fishes is vital for maintaining healthy fisheries by mitigating our negative impact on the ocean.

Looking at juvenile ambon damselfish (Pomacentrus amboinensis) in the Great Barrier Reef with motorboats passing at different distances from them, we observed that their metabolisms were more elevated the closer the boat was to them. This stress can cause negative effects on many areas of their physiology. We found that they also had reduced startle behaviour and did not retreat from a threat as readily in experiments with boats passing very close to them. This effect was diminished at further proximities as the sound attenuated over distance. We found that keeping boat lanes and the majority of water traffic at more than 100 m from reefs would reduce the negative effect caused by this noise.

Our understanding of the role of sound in the ocean is in its infancy, but we do know just how important it is for marine organisms and their survival. As humans we need to make sure that fishes can still use their soundscape to find habitats and avoid predators, especially when they are facing so many other threats already.

Lund University advisor: Anders Persson
University of Exeter advisor: Steve Simpson
Degree project 60 hp in Biology: Aquatic ecology 2018-2019.
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Holmes, Roxanne
supervisor
organization
course
BION03 20182
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8979026
date added to LUP
2019-06-03 14:32:08
date last changed
2019-06-03 14:32:08
@misc{8979026,
  abstract     = {Underwater soundscapes provide valuable information for the survival of fishes. These auditory cues create “acoustic daylight” to help guide orientation to coastal areas for settlement and govern movements and between habitats in post-settlement recruits. In the temperate French Mediterranean Sea, acoustic recordings in addition to Underwater Visual Census (UVC) of the white seabream (Diplodus sargus) show that the total abundance of juveniles is significantly associated with areas of a high root-mean-squared sound pressure level (SPLrms) in the lower frequency range (1 Hz –5 kHz), especially within the bandwidth associated with urchin sounds (700 Hz –2 kHz). The Acoustic Complexity Index, Acoustic Richness, and the number of snaps produced by snapping shrimp were not found to have any significant association with the total abundance of seabream recruits. Size of recruits was found to play a role in the relationship between abundance and soundscape, as significant relationships were only found between small recruits (40–50 mm) and not in larger recruits (60–70 mm), who may have settled earlier in the season. Benthic habitat surveys revealed that SPLrms of various bandwidths was significantly correlated with the benthic substrate and may be the most reliable indicator in habitat selection by recruits postsettlement. The strong links between the soundscape and the abundance of recruits suggests that the use of acoustic data may be a valuable addition to the long term monitoring of D. sargus populations and help with predicting and protecting potential high density nursery areas over time.},
  author       = {Holmes, Roxanne},
  language     = {eng},
  note         = {Student Paper},
  title        = {Safe and sound: A: Soundscapes and seabream, B: Sound and survival},
  year         = {2019},
}