What’s all that racket! Soundscapes, phenology, and biodiversity in estuaries

5 species of invertebrates and 54 species of fish during seining of which some of these species are capable of producing sound (S5 Table). However, many of the fish species caught in the seines were young-of-the-year, and sound production of these juveniles is unknown (S5 Table). We detected temporal patterns in species richness, the Shannon-Wiener diversity index, and abundance for invertebrates and fish species. We found lower species diversity and abundance during wintertime (i.e. cooler season), and higher species diversity and abundance during spring and summertime (warmer seasons). This temporal pattern of species diversity and abundance followed the warming and cooling patterns of the estuary as well as the oscillat- ing pattern of the biological soundscape (Fig 4 and S14 Fig). We found significant positive cor- relations between species richness (as well as the Shannon-Wiener diversity index and abundance) with high, low, and broadband SPLs (S15A–S15C Fig, S15E–S15G Fig and S16A– S16C Fig); the highest correlations occurred with low frequency SPL (S15B and S15F Fig). In addition, we found a significant positive regression between water temperature and species richness (as well as Shannon-Wiener diversity index) but not between temperature and species abundance (S15D and S15H Fig, and S16D Fig). Spatially, overall years, the highest species richness, Shannon-Wiener Diversity index, and species abundance occurred at station 14M, where we observed the highest SPL values (Fig 4 and S14 Fig).

Fig 4. Time series of broadband frequency SPLs, species richness, and species abundance from 2016 until 2018. Heat maps represent temporal and spatial patterns of broadband (1–40,000 Hz) frequency SPLs reflecting all biological sounds with corresponding species richness (black line), species abundance (blue dash line), and temperature (red line) at stations (A) 9M, (B) 14M, and (C) 37M in the May River. Gaps in data = white. This dataset contained files with physical sounds and anthropogenic noise. https://doi.org/10.1371/journal.pone.0236874.g004 PLOS ONE Estuarine soundscapes and biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0236874 September 3, 2020 6 / 18