Freshwater ecosystems such as rivers and lakes are heavily threatened by a multitude of stressors, including noise pollution by human activities. Noisy activities on and in the water, such as the... Show moreFreshwater ecosystems such as rivers and lakes are heavily threatened by a multitude of stressors, including noise pollution by human activities. Noisy activities on and in the water, such as the prominent use of motorized boats, may alter natural underwater soundscapes. Traffic noise and sound from other human activities on land may also penetrate into the water, especially through bridges. Natural soundscapes vary with hydro-morphological variation among river types and sections and with the heterogeneity in local diversity of sound-producing animals and plants. Natural soundscapes may play an important role in orientation and navigation, in particular for migratory fishes, but still very little is known. It is clear that anthropogenic noise may deter, disturb, distract, and mask natural soundscapes, but few studies have addressed the extent of potential masking impact in freshwater systems. Many rivers flow through urban areas, where typically many bridges provide crossing opportunity to noisy road traffic. Weeklong underwater recordings reveal diurnal and weekly fluctuations of sound pressure levels (SPLs) in underwater soundscapes, likely related to road traffic over urban bridges, in a Dutch lowland river system. Weekdays and weekends can acoustically be distinguished in these underwater soundscape profiles. These results provide insight into the potential for noise pollution impact on migratory fishes and other aquatic animals. Show less
'Blinding' involves concealing knowledge of which trial participants received the interventions from participants themselves and other trial personnel throughout the trial. Blinding reduces bias... Show more'Blinding' involves concealing knowledge of which trial participants received the interventions from participants themselves and other trial personnel throughout the trial. Blinding reduces bias arising from the beliefs and expectations of these groups. It is agreed that where possible, blinding should be attempted, for example by ensuring that experimental and control treatments look the same. However, there is a debate about if we should measure whether blinding has been successful, this manuscript will discuss this controversy, including the benefits and risks of measuring blinding within the randomised controlled trial. (c) 2021 Elsevier Inc. All rights reserved. Show less
