Anthropophony effects on acoustic metrics in a marine soundscape
Lopes, L.C.; Oliveira, E.G.; Clark, C.W.; Sousa-Lima, R.S. (2024). Anthropophony effects on acoustic metrics in a marine soundscape, in: Popper, A.N. et al. The effects of noise on aquatic life: Principles and practical considerations. pp. 555-573. https://dx.doi.org/10.1007/978-3-031-50256-9_156 |
| Keywords | Megaptera novaeangliae (Borowski, 1781) [WoRMS]
Marine/Coastal | | Author keywords | Passive acoustic monitoring · Long-term monitoring · Acoustic index· Humpback whale |
| Authors | | Top | - Lopes, L.C.
- Oliveira, E.G.
- Clark, C.W.
- Sousa-Lima, R.S.
| | |
| Abstract | Anthropogenic noise is known to influence acoustic environments and the habitats of marine species. Acoustic indices used to evaluate relative contributions of and trends in anthropogenic noise have had mixed success when applied to marine environments. This study assessed which acoustic metrics represent the level of anthropogenic activity within Abrolhos Bank, the most important humpback whale (Megaptera novaeangliae) breeding site in the western South Atlantic. Metrics included power spectral density (PSD), long-duration false-color (LDFC) spectrograms, ribbon plots, and nine acoustic indices. Metrics were calculated within a control area with low vessel traffic and a treatment area with high vessel traffic. Contributing sound sources included vessels, humpback whales, and fish species. The treatment area had higher PSD levels, indicative of high vessel noise conditions. Normalized difference soundscape index (NDSI), acoustic events (EVN), and acoustic complexity index (ACI) scored lower for higher levels of anthropogenic noise. ACI was influenced by high levels of humpback vocal activity and should be used with caution as a diversity proxy. LDFCs clearly confirmed the presence of singing humpbacks, fish choruses, and vessels, but only humpback songs were evident in ribbon plots. Findings in this chapter confirmed that PSD and spectral probability density plots are the current best way to characterize anthropophony within marine soundscapes. |
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