Can acoustic tools boost restocking success in coral reef fish larval culture and release?

Abstract

Fish are among the most diverse and abundant group in the tropical coral reef community. The contribution of fish to the sustained resilience and health of coral reefs should not be understated. As anthropogenic pressure and environmental change challenge the healthy function of tropical coral reefs globally, the need for conservative and restorative human intervention is becoming increasingly important. Of the currently applied coral reef restoration methods, scleractinian corals have received the most awareness being the backbone of the reef ecosystem. Fish are often overlooked in this respect, however the diversity of fish on newly restored or recovered coral reefs may not reflect the species richness and population size it was prior to degradation. Therefore, the conservation and restoration of fish should receive the attention equivalent to their importance within the ecosystem. This thesis examines the importance of fish for the tropical coral reef ecosystem, highlighting the negative effects of the degradation of fish communities on the health of the coral reef. Furthermore, to understand the vulnerability of coral reef fish throughout their life history, I focus on the ultra-high predation experienced by fish during the pelagic larval stage and the settlement window. In doing so, I explore the current understanding of the sensory cues larval and juvenile coral reef fish are sensitive to, and how they use these cues to coherently navigate such a dangerous environment. Finally, I use this information to identify knowledge gaps regarding the ecological efficiency of different coral reef fish restoration methods. Based on this evaluation, I apply emerging post-larval capture, culture and release methodology, using our existing understanding of post-larval fish sensory abilities to refine current practice. Conducting a survivorship experiment on Lizard Island in Northern Queensland, Australia, I tested the effect of playback acoustic enrichment both in aquaria, and in the field on the survival of Pomacentrus amboinensis up to 72 hours post release. Fish collected via light trap were cultured for a maximum of 8 days, whereupon they were released onto individual patch reefs. During the 72-hour monitoring period, in addition to the survival of tagged P.amboinensis, data was also collected regarding the abundance of wild fish associating with the experimental patch reefs. I recorded an increased survival probability of P.amboinensis in response to aquarium acoustic enrichment, however due to the low replication of this experiment, this result was not statistically significant. I did not observe any effect of acoustic enrichment of the experimental patch reefs on the survival of P.amboinensis. This data suggests that the attraction of wild fish to the experimental patch reefs could be influenced by the acoustic enrichment of P.amboinensis, although greater replication is necessary to provide statistical significance.

Date of Award	20 Jan 2026
Original language	English
Awarding Institution	University of Bristol
Supervisor	Hugo B Harrison (Supervisor) & Steve Simpson (Supervisor)