Navigating Soundscapes: Attractant effect of reef sound on oyster settlement may be attenuated by vessel noise

Abstract

Abstract Settlement is a critical period in the life cycle of benthic species with planktonic larval stages and for reef building invertebrates such as oysters and corals; settlement rates are predictive for reef restoration and long-term survival. Increasing evidence suggests that marine invertebrates use information from ocean soundscapes to inform settlement decisions. Sessile marine invertebrates with a settlement stage are particularly reliant on environmental cues to direct them to ideal habitats as settlement location is permanent. As gregarious settlers, oysters prefer to settle amongst members of the same species. It has been hypothesized that planktonic larvae use distinct oyster reef sounds to navigate to ideal habitats. In controlled laboratory experiments, we show that sounds recorded at conspecific reefs induce higher percentages of settlement in larvae of the Pacific Oyster Magallana gigas. Additionally, we exposed larvae to anthropogenic sounds from several different vessels, combined reef-vessel sounds as well as off-reef and no sound controls. Our results suggest that attractive reef noises may be masked by vessel sounds, however, this observation is substantiated by a nonsignificant trend. Examining the acoustic characteristics of the preferred reef sounds, we hypothesize that spectro-temporal patterns are the driving attractive quality in reef sounds for this species.