Soundscape and riverscape dataset of Gregoire stream, located in southern Québec (2017)

Abstract: Data were collected in the summer 2017 in a second order stream of 1150 meter long with the objective to evaluate the overlap between hydromorphological and acoustical habitat features at high spatial resolution within a stream. This dataset contains 593 sample sites that measured underwater acoustic profile in term of decibel (ref: 1uPa) per 1 hertz frequency (from 1Hz to 22000Hz), water depth and velocity, stream width, primary and secondary substrate and habitat type.

Method: The study was conducted in Gregoire Stream, a second-order stream in southern Quebec, Canada (46°05'40''N, 71°25'58''W). The area has a rain-snow regime characterized by peak water flows in spring and low flows in summer. We delineated a reach of 1150 m in length characterized by a flat low-flow section at the upstream end (stream distance = 1150 m) and a series of waterfalls at the downstream end (stream distance = 0 m), near to the confluence of Gregoire Stream and the Bagot River. The reach was crossed by a road which separated two zones differing in slope and riparian vegetation; a downstream zone having steeper slope and forest cover and an upstream zone having shallower slope and mostly shrub cover.

The measure of hydromorphological habitat descriptors included water velocity (m s-1), water depth, stream width (cm), and primary and secondary substrate dominance. These variables were measured in 50 2.5-m sections. The sections were randomly selected without replacement from a uniform distribution over the section identifiers, on for occasions. The same set of variables was also measured in sections where fish were caught (with electrofishing). Water depth was measured at the center of the section and stream width across the wet streambed. In each section, mean water velocity was measured (Global Water Flow Probe model FP111) by slowly moving the probe up and down the water column continuously for 40 seconds. We assessed the dominant and sub-dominant wet substrates using the Wentworth granulometric scale (Wentworth 1922). In addition to hydromorphological measurements, stream habitat units were categorized using the classification system of Bisson et al. (1982), distinguishing six habitat types: pool, glide, run, riffle, cascade, and waterfall base. The length of each habitat unit along the reach was measured to the nearest 0.5 m, yielding a measure of the length of each unit.

For the underwater soundscape, we recorded one 10-second underwater audio clip in each 2.5-m stream section immediately after we had collected hydromorphological measurements (water velocity, water depth, stream width, substrate type). We ensured by this procedure a close correspondence between the acoustical and the hydromorphological variables in time and space.

Underwater sounds were recorded along the stream reach using a H1 hydrophone powered by a PA4 amplifier (Aquarian Scientific, Anacortes, USA) and connected to a digital recorder (H2n Recorder, Zoom, Tokyo, Japan). A total of 593 10-second audio clips were recorded (16-bit WAV format at a sampling rate of 44.1 kHz) at a depth of 5 cm below the water surface. Each audio clip was listened with earphones to ensure that the hydrophone was not rubbing on hard surfaces while recording. The recording system has a maximum input of 10 V (rms) and a rated sensitivity of -190 dB re 1 V/µPa over the flat frequency-response range 10–3,000 Hz. Above specifications were used to obtain referenced sound pressure level (SPL) (dB re 1 µPa) with the PAMGuide functions (Merchant et al. 2015). For each audio clip, the frequency spectrum averaged through time was calculated to obtain referenced SPL values in 1-Hz frequency bands over the 0.1-10 KHz range. This procedure yielded a total of 22049 dB values per audio clip.