Semester of Graduation

Fall 2021

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

The invasive red lionfish, Pterois volitans, has been shown to considerably reduce reef biomass via predation and competition in non-native ranges. Primary maintenance of lionfish is through human removal (e.g., culling), which does not sufficiently control the population due to deep-water spawning, recolonization of recently culled reefs, and ontogenetic migrations to mesophotic waters. Here, I investigated the diets and primary energy pathways during ontogeny in lionfish from the Florida Keys using stomach contents and stable isotope (δ13C and δ15N) analysis to better understand their role in the trophic food web. Additionally, isotopic overlap between lionfish and native reef predators was examined to assess shared energy resource use that could be indicative of competition. Lionfish (n=48) and other community representatives were collected from a mosaic of habitats in the Florida Keys (i.e., mangroves, seagrass beds, and coral reefs) in August 2020. Findings revealed lionfish on deep (60 – 90 ft) reefs utilize a wider variety of basal carbon sources compared to lionfish on intermediate (40 – 50 ft) and shallow reefs (20 – 25 ft). Furthermore, using length as a proxy for age, stable isotope analysis did not indicate ontogenetic migrations of lionfish between shallow water habitats in the Florida Keys. Bayesian mixing models predicted reef POM to be the greatest primary production source contributor to lionfish and reef fish primary energy pathways, and a high degree of resource use overlap between lionfish and native reef fish was seen. This extensive isotopic overlap among lionfish and native reef fish indicated that the extent of shared resource use may be underestimated. The additional knowledge gained in this study on lionfish habitat use and population dynamics illuminates their role in shallow water ecosystems while introducing the need to regionally assess lionfish primary energy pathways and shared resource use in order to fully understand the role of lionfish in each local food web.

Committee Chair

Cassandra Glaspie

Available for download on Friday, October 14, 2022

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