Date of Award

12-14-2023

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Ryan Rezek

Second Advisor

Derek Crane

Third Advisor

John Hutchens

Abstract

Invasive species threaten the ecological integrity of ecosystems worldwide, including the Florida Coastal Everglades. This study investigated the ecological role of the peacock eel (Macrognathus siamensis) within this ecosystem, emphasizing its population trends and the environmental factors that affect its population performance, and the potential for interactions with native fish assemblages and coastal food webs. I used 19 years of electrofishing data to investigate the population trends of peacock eels at the marsh-mangrove ecotone of the Shark River Estuary, Everglades National Park (Florida, USA). I found that peacock eel populations have increased since their first detection in 2002, and their populations are strongly affected by hydroclimatic regimes—with warmer water temperatures and greater marsh inundation periods explaining greater abundance. I used stable isotope analysis of carbon, nitrogen, and sulfur to provide insights into the basal resource contribution to peacock eels and to determine peacock eel niche size and overlap with native species using hypervolume analysis. With these analyses, I found that peacock eels have the potential to compete with native sunfishes (Lepomis spp.). The trophic niche of peacock eels, though significantly smaller in volume, overlaps 98.8% with that of native sunfishes. Competitive interactions between peacock eels and native sunfishes could disrupt the niche of sunfishes and subsequently alter marsh prey subsidies on which coastal fisheries rely. In recent years, the catch of peacock eels has outnumbered the catch of all species of native sunfish combined. Peacock eel populations are expected to increase as the climate continues to change and cold weather events that are currently limiting their population growth become less frequent.

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