Effects of seismic sound on zooplankton

At what range is zooplankton affected by seismic surveys? That is the focus of this four-year research project (ZoopSeis). The sea is not as quiet as often portrayed. Natural processes, such as wind and waves, animals, and human activities, produce sounds. Many animals use natural sounds to gain information about their environment. Loud impulsive sounds may also lead to stress and even physical damage close to the sounds source. We have limited knowledge of the importance of sound for zooplankton, and published studies provide contradictory results about at what range zooplankton can be damaged by the sound from seismic surveys. Therefore, we test by what mechanism sound can damage zooplankton and how strong these forces need to be. We model at what distance from an airgun zooplankton could be damaged, and tested the results from the model in a field experiment. In addition, in laboratorium experiments, we test which mechanisms could affectzooplankton. The results will be used to provide advice on how to minimize the negative impact of seismic surveys in areas with high zooplankton concentrations.

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Anthropogenic noise from seismic surveys has been documented to affect fish and marine mammals both in terms of physical injury and changes in behaviour. However, data on lower taxa are scarce. Two recent studies show highly contradicting results. A study by McCauley et al. (2017) indicates that seismic blasts may kill various species of zooplankton in Australia at distances of up to 1200 m from an airgun, while another study (Fields et al. in press) reports no mortality or sublethal effect at distances >10m from a seismic blast in Norway. These highly contradictory results suggest that effects may be variable and highly dependent on species and geographic area. To predict at what ranges a seismic survey can impact zooplankton populations, a thorough understanding of the mechanism behind such effects is crucial. In this project, we will use a combination of modelling and laboratory to address what forces can induce injury and mortality in zooplankton, and at what ranges from a seismic survey such forces could be strong enough to have a lasting impact. We will focus on direct mortality, reproductive output and predator avoidance to assess both immediate and delayed effects. In addition, we will use field studies to verify predicted effects on natural population and to assess the potential for avoidance. The results will be used to provide advice on how to minimize the negative impact of seismic surveys in areas with high zooplankton concentrations.