Anthropogenic sound as an emerging threat in the Caspian Sea: The potential effects of sound on aquatic animals

Ambient sound levels have risen dramatically over recent decades due to sound-generating human activities, so-called anthropogenic sound, in marine and freshwater habitats. In accordance with the World Health Organization (WHO), anthropogenic sound is recognized as a significant global pollutant. Anthropogenic sounds can vary in terms of temporal, spatial and structural patterns. Aquatic animals may use sounds to communicate with individual conspecifics, detect prey and avoid predators in their natural habitats. The Caspian Sea is a brackish-water habitat and the largest lake in the world. There is a diversity of aquatic animals that inhabit the Caspian Sea. However, to our knowledge, soundscapes and the potential effect of anthropogenic sound pollution on aquatic animals of the Caspian Sea has not been investigated. In this paper, we argue that we need to prioritize acoustic studies to understand the soundscape and bioacoustics criteria of the Caspian Sea, and assess the potential impacts of acoustic stimuli on aquatic animals at the individual and community level.