The sound of river - A trigger for riverine biota

Organisms have developed a variety of methods to gather, process and respond to information about their environment. In addition to visual, tactile and olfactory information, auditory stimuli are an essential source of information. In terrestrial and marine ecosystems, their importance is well known. For riverine ecosystems, however, there is almost no information available on whether auditory stimuli are important for aquatic and semi-aquatic organisms, and if so, which significance they have. A basic understanding of these processes is essential to answer basic ecological but also specific applied questions related to environmental and nature conservation issues. Within the next two years, the research project "The sound of rivers - a trigger for riverine biota?" will investigate to what extent acoustic signals in rivers are perceived and used as a source of information on the physical environment. The focus will be on specific sound characteristics of natural (floods) and anthropogenically induced water level changes (hydropeaking phenomena) as well as their impact on the behaviour of invertebrates and fish. Of particular importance is the question of whether the resulting altered soundscape can potentially serve as an early warning system for organisms. Within the frame of this so-called high-risk research project, the role of hydro-acoustics in orientation of aquatic organisms in a dynamic habitat will be assessed generating important information on fundamental questions of aquatic ecology.

The sound of rivers - a trigger for riverine biota? Organisms have developed a variety of methods to gather, process and respond to information about their environment. In addition to visual, tactile and olfactory information, auditory stimuli are an essential source of information. In terrestrial and marine ecosystems, their importance is well known. For riverine ecosystems, however, there is almost no information available on whether auditory stimuli are important for aquatic and semi-aquatic organisms, and if so, which significance they have. A basic understanding of these processes is essential to answer basic ecological but also specific applied questions related to environmental and nature conservation issues. The research project entitled "The sound of rivers - a trigger for riverine biota?" has therefore spent the past two years investigating the extent to which acoustic stimuli in rivers are perceived and used as a source of information on the physical environmental situation. The main focus was on the sound characteristics of natural (floods) and anthropogenic water level changes (surge-sunk phenomena) and their impact on the behaviour of invertebrates and fish. Of particular importance was the question of whether the resulting altered soundscape could possibly serve as an early warning system for organisms. In this so-called "high-risk research project", the role of hydroacoustics for the orientation of aquatic organisms was investigated experimentally. The results cannot be interpreted unambiguously, but represent an important introduction to hydroacoustics and its effects on organisms. Furthermore, they lead to the possibility of new perspectives and the development of new hypotheses, and the methods developed are an essential basis for the adaptation of further experimental approaches.