Larval settlement in response to estuarine soundscapes

Abstract

Ambient underwater sound has the potential to be an important orientation and settlement cue for marine invertebrate larvae, yet larval responses to relevant sound patterns are largely unknown. In estuaries of the Southeastern United States, oyster reefs are patchy productive habitats that harbor many soniferous fish and invertebrates, creating distinct sound characteristics. This habitat-related sound could provide a useful cue for the planktonic larvae of obligate reef dwellers and facilitate encounter with suitable settlement substrate. To investigate sound as a settlement cue in this system, larval settlement responses to oyster reef and soft-bottom sounds, as well as a no-sound control were tested for the Eastern oyster, Crassostrea virginica. Laboratory and field experiments suggest that sound has a significant effect on oyster settlement rates: higher numbers of larvae settled in the presence of oyster reef sounds than in soft-bottom sound or silent control treatments. Improved understanding of the relationship between habitat sound fields and subsequent larval recruitment is central to bio-physical studies of larval connectivity and recruitment in marine systems.