The Role of Backreef Soundscapes and their Spatial Structure for Recruitment of Tropical Marine Larvae

<p>Underwater sound is a cue used by many marine larvae to orient to coastal habitats including backreef, sponge-dominated hardbottom habitat in the Florida Keys (Florida, USA) – a particularly “noisy” coastal habitat. However, the distance over which acoustic cues are attractive to settlement-stage larvae - is generally unknown. I examined this phenomenon in a region of the Florida Keys where mass sponge die-offs have diminished both underwater soundscapes and larval settlement. The absence of pronounced hardbottom-associated sound over such a large area allowed me to experimentally test in situ the response of fish and invertebrate larvae to broadcasted sounds at different distances from their source. I first measured sound recording from healthy hardbottom habitat at seven distances from an underwater speaker to determine the maximum range of the signal. Based on those results, larval collectors were then deployed at 10, 100, 500, and 1000 m from speakers broadcasting sounds recorded at either degraded or healthy hardbottom sites for five consecutive nights during each of three new and full moon periods in summer/fall 2019. Larval settlement onto those collectors was affected by lunar phase and soundscape type, but the effect of distance on larval settlement varied among species and, in most cases, the effect was small and not likely to be ecologically significant. The absence of a strong larval settlement response to a sound cue lies in contrast to results from other studies. I hypothesize that the small (m) radius of the broadcasted soundscapes may have limited the magnitude of the larval response to locally available larvae and because the experiment within a large, relatively quiet seascape where local larval abundance may have been low. If so, then planktonic larvae may require a series of acoustic “sign-posts”, perhaps in combination with other cues (e.g., chemical), to successfully orient to distant nursery habitats. Although habitat restoration efforts may be able to restore healthy soundscapes, the typically small size and number of restoration sites may limit the range of the acoustic cue and larval attraction to restored habitats.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2021

Author dc:creator

• Anderson, Emily R.

Contributors dc:contributor

• Mark J. Butler
• Jack Butler
• Holly Gaff

• Florida Bay
• Hardbottom
• Larvae
• Marine soundscapes
• Settlement
• Underwater sound
• Biology
• Ecology and Evolutionary Biology

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9798515246518

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biology_etds-1119