Hdr pj675

To evaluate the impact of noise treatments on swimming activity and anxiety-like behaviour, two fish from each acoustic treatment tank were tested with the Novel Tank Diving (NTD) assay^{62 (link)} immediately following the treatments. NTD was tested in a rectangular-shaped glass transparent tank (26 cm length × 13 cm width × 19.5 cm height) filled with 4 L of system water. To perform NTD test, a single fish was simply transported to the experimental tank and the behaviour recorded with a digital camera (SONY HDR-PJ675, Japan) for 6 min. The water from the experimental tanks was replaced between trials to avoid potential effects from chemical cues.
Videos were analysed using EthoVision XT 15 (Noldus Information Technology, Netherlands) to generate a tracking line for each individual fish. To measure the vertical exploratory activity, the tank was divided into two equally sized areas (top and bottom), as shown in Fig. 5D. Specific parameters were calculated based on the overall 6 min recording: mean velocity (cm/s)—overall swimming distance divided by recording time; latency to the top zone (s)—time interval between the beginning of the trial until the first entry in the top zone; percentage (%) of time spent in the bottom zone—amount of time in the bottom zone per each consecutive 60 s, and the number of top zone entries.

The free play in the playground was recorded on November 27, 2018 (referred to as “before the alteration”) and on January 23, 2019 (referred to as “after the alteration”). The alteration of the spatial layout of the playground was implemented on December 16, 2018. Video recording was performed with three cameras (Sony HDR-PJ675), which were set to record most of the playground. The climate of the area was warm, and the temperature on the day of observation was 19°C for before the alteration and 16°C after the alteration. All participants wore long sleeve T-shirts and sometimes rolled up their sleeves. At the center that we observed, children usually have free, unstructured outdoor play time from around 10:30 A.M. to 12:00 P.M., without any instructions from caregivers. The observation time was 97 min for before the alteration and 87 min for after the alteration.