"Differences in Secondary Consumer Behavioral Responses to Predators on" by Lauren E. Dalton

Defense Date

12-3-2021

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Fraser Januchowski-Hartley, Ph.D

Second Advisor

Andrew Bauman, Ph.D

Third Advisor

Margaret Malone, Ph.D

Keywords

invertivorous fishes, foraging behaviors, predation risk, fear effects, predator-prey interactions, predator models

Abstract

On coral reefs, intensifying local stressors and climate change reconfigure reef ecosystems, with largely unknown implications for critical ecosystem functions (i.e., predation and secondary consumers). The study investigated differences in fish assemblages on natural and artificial reefs and how predator presence affected secondary consumer (i.e. invertivorous fish) abundance and foraging behaviors on natural versus artificial reefs. The specific objectives of this study were: (i) determine whether secondary consumer abundances differ between artificial and natural reefs and (ii) assess how predator identity influence the foraging behavior of secondary consumers. The study was conducted on shallow natural and artificial reefs in Broward County. Point count surveys measured species abundance and species communities. Standardized assays using dried squid, (i.e., “squidpops) in conjunction with predator treatments, measured fear effects through underwater video surveillance. Secondary consumer responses were quantified to threat treatments: a black grouper (Mycteroperca bonaci) model, a great barracuda (Sphyraena barracuda) model, an object control, and a control. We found significantly greater fish abundances and differing species communities on natural reefs than artificial reefs. Fish reduced foraging differences between natural and artificial reefs, potentially due to encounter rates; however, the exact mechanism driving this pattern remains unknown. Fish perceive a difference between predator treatments, with more perceived risk to the grouper model, suggesting predator identity impacts secondary consumer foraging. In conservation, enhancing structural complexity in artificial reefs can support diverse fish communities and natural predator-prey interactions. Future research should explore habitat features that optimize foraging and defense, boosting fish resilience and marine ecosystem.

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