Abstract
Artificial reefs are used widely throughout the Southwest Florida shelf to increase available fish habitat, support recreational activities, and contribute to the coastal economy. However, these nearshore habitats, and the associated fish that inhabit them, may be influenced by surrounding water quality conditions and land-based contaminant inputs. Many pesticides used in residential, commercial, and agricultural settings, such as pyrethroids and organophosphates, can enter coastal systems through stormwater runoff, estuarine discharge, and other land-based pathways. Pyrethroids, commonly used for mosquito control, are highly toxic to many fish species, in part because fish have a limited capacity to metabolize and detoxify these compounds compared with many terrestrial vertebrates. This sensitivity may increase risk for nearshore fishes that are repeatedly exposed to pyrethroid inputs from land-based use. This thesis evaluated Kimberly’s Reef, a newly deployed artificial reef on the Southwest Florida shelf, as both a developing fish habitat and a potential site of pesticide exposure. Fish community development was assessed using visual surveys over the first three years of deployment from March 2023 to March 2026. Fish colonized Kimberly’s Reef rapidly, while community composition continued to develop over time, indicating continued reef development and possible stabilization of fish assemblages. Seasonal and water-quality variability helped explain shifts in fish community structure, suggesting that small seasonal changes influence utilization of the reef. To measure pesticide distributions, select pesticide concentrations were quantified from grab water samples, passive samplers, and fish tissues at the reef using Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS). Common snook were also exposed to an acute, low dose of permethrin in a laboratory experiment to assess physiological effects of exposure. Pesticides, including naled and permethrin, were detected across multiple sample types, including water and fish tissues, demonstrating that contaminant exposure is occurring in a nearshore reef habitat used by recreationally and ecologically important species. Resident fishes, including sheepshead, white grunt, and mangrove snapper, accumulated pesticide mixtures in their tissues, with higher burdens in the gills and liver. Laboratory exposure results further showed that low-dose permethrin exposure altered superoxide dismutase activity in common snook, suggesting that environmentally relevant pesticide exposure can alter oxidative stress responses.
Overall, this thesis demonstrates that Kimberly’s Reef is being utilized as fish habitat, but that these communities are impacted by water quality and possibly measurable contaminant exposure. These findings suggest that nearshore artificial reefs should be evaluated not only by fish presence, abundance, or habitat development, but also by the water-quality conditions and contaminant exposure associated with their placement. Integrating fish community monitoring with contaminant assessment can provide a more complete understanding of artificial reef function and help guide coastal management in human-influenced systems.