Abstract
Human exploitation of the sea has altered marine soundscapes. Much of marine life heavily depends on the use of sound. Artificially elevated sound levels, generated by shipping, naval exercises, construction or exploration, can mask acoustic signals and interfere with foraging and reproductive behaviour. Potential consequences for threatened species and sensitive ecosystems are of international concern. Nevertheless, mitigation efforts are handicapped by key gaps in our knowledge on the effects of noise on populations and food web dynamics. The marine habitat is challenging to researchers, while animal behaviour is rarely visible at the surface. We typically just have evidence for simple behavioural effects on single species. However, pertinent evidence for impact of man-made sounds on top predators and species interactions that are key to food web dynamics is critical for our understanding of noise impact on marine ecosystems and urgently needed to inform managers and regulators. Here, I propose an experimental study on two top predators and two distinct prey guilds. The main objective is to assess the impact of noise on representative baleen and toothed whale species, hunting for krill/small fishes and squid/large fishes respectively. I will do so by experimental elevation of sound levels during foraging bouts, using an innovative combination of four advanced sensors: 1) non-invasive digital archival tags and 2) on-animal camera tags record foraging behaviour, capture rates, body condition, sound levels at the whale and prey targets, 3) a camera-drone visualises whale group dynamics and body size from the air and 4) echo sounders assess prey communities and schooling responses to sounds and predators. Field playbacks are matched with captive experiments assessing fine-scale noise responses of prey. The unique combination of data will reveal whether increased sound levels affect whale foraging efficiency and whether this is due to an effect on predator, prey or both.
Netherlands