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- Title
- CASCADING EFFECTS OF PREDATOR REMOVAL ON THE ECOLOGY OF SEA TURTLE NESTING BEACHES.
- Creator
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Barton, Brandon, Roth, James, University of Central Florida
- Abstract / Description
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Traditional views of food web dynamics have characterized species interactions as linear and direct. However, modern food web theory suggests that interactions can also be nonlinear and indirect, so that disturbance at one trophic level is transmitted throughout the community. Many previous studies have demonstrated that the removal of top predators from terrestrial ecosystems can have broad-scale impacts on community ecology. I examined the direct and indirect effects of raccoon removal from...
Show moreTraditional views of food web dynamics have characterized species interactions as linear and direct. However, modern food web theory suggests that interactions can also be nonlinear and indirect, so that disturbance at one trophic level is transmitted throughout the community. Many previous studies have demonstrated that the removal of top predators from terrestrial ecosystems can have broad-scale impacts on community ecology. I examined the direct and indirect effects of raccoon removal from sea turtle nesting beaches in east-central Florida during the summers of 2003 and 2004. Raccoon and ghost crab predation are among the highest causes of egg mortality for sea turtles in Florida and raccoons are intraguild predators of ghost crabs. Because of the damage done to sea turtle nests, raccoons have been removed from some beaches during the sea turtle nesting season. I compared the diet and demography of a raccoon population that had experienced two decades of raccoon removal to a population that had previously been unmanipulated. I found that long-term raccoon removal had created a significantly male-biased sex ratio in that population. I also examined the indirect effects of raccoon removal by comparing the abundances of raccoons and ghost crabs at four study sites using passive tracking plots. My data suggest intraguild predation by raccoons limits ghost crab abundance and that reduced raccoon abundance allowed ghost crab abundance to increase, resulting in a net increase in sea turtle egg predation. These results support my hypothesis that intraguild predation of ghost crabs by raccoons is an influential interaction on sea turtle nesting beach community dynamics.
Show less - Date Issued
- 2005
- Identifier
- CFE0000521, ucf:46466
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000521
- Title
- Testing for Isolation in Florida Raccoons (Procyon lotor) Using Phylogenetics and Population Genetic Structure.
- Creator
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Trujillo, Alexa, Hoffman, Eric, Fedorka, Kenneth, Parkinson, Christopher, University of Central Florida
- Abstract / Description
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Molecular data are useful in determining if populations are isolated and for species delimitation. Researchers and managers currently recognize five subspecies of raccoons (Procyon lotor) in Florida, based largely on perceived geographic isolation due to the island ranges of four subspecies. In this study, I provide the first estimate of phylogenetic relationships and population divergences within Florida raccoons using a molecular dataset. I analyze the mitochondrial control region,...
Show moreMolecular data are useful in determining if populations are isolated and for species delimitation. Researchers and managers currently recognize five subspecies of raccoons (Procyon lotor) in Florida, based largely on perceived geographic isolation due to the island ranges of four subspecies. In this study, I provide the first estimate of phylogenetic relationships and population divergences within Florida raccoons using a molecular dataset. I analyze the mitochondrial control region, cytochrome b gene, and eight nuclear microsatellite loci to test two hypotheses: 1) the five, morphologically and geographically-defined subspecies of raccoon in Florida represent genetically distinct populations and (2) due to differing range sizes and habitat variation between island and mainland subspecies, the four island populations should exhibit reduced levels of genetic diversity and smaller effective population sizes compared to the mainland population. My results indicate no evidence of historical differentiation between the subspecies, but suggest a recent restriction of gene flow among three clusters of raccoons. The three clusters do not correlate to traditional geographies for subspecies identification. I provide evidence of reduced genetic diversity in island populations of raccoons compared to their mainland counterparts. These data stress the importance of using multiple lines of evidence when naming taxa to avoid misinforming the taxonomy.
Show less - Date Issued
- 2015
- Identifier
- CFE0006233, ucf:51069
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006233
- Title
- FACTORS AFFECTING PREDATION OF MARINE TURTLE EGGS BY RACCOONS AND GHOST CRABS ON CANAVERAL NATIONAL SEASHORE, FL.
- Creator
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Brown, Justin, Roth, James, University of Central Florida
- Abstract / Description
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Changes in abundance of interactive species can have cascading, community-wide effects (Soulé et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons--the most obvious egg predator--which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost...
Show moreChanges in abundance of interactive species can have cascading, community-wide effects (Soulé et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons--the most obvious egg predator--which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost crab density on egg predation are well understood. I studied raccoon-ghost crab interactions and the effects of environmental variation on their activity during the 2007 marine turtle nesting season on Canaveral National Seashore, FL. My goal was to model predator activity and identify efficient management strategies to reduce egg predation. Raccoon activity increased with increasing habitat diversity and edge of the dominant cover type, coastal strand. Raccoon activity increased locally and became less variable near segments of beach accessed for human recreation, but activity was greater on undeveloped beach, where habitat diversity and edge were greater. Ghost crab density and size were primarily affected by sand characteristics and recreation but decreased with increasing raccoon activity in June, which may have contributed to sustained declines in ghost crab density. Hatching success of marine turtles decreased with increasing ghost crab egg predation, suggesting ghost crabs are an important cause of egg mortality and not merely scavengers on unhatched eggs. Egg predation by ghost crabs was unrelated to ghost crab density or size, likely a result of monitoring limitations, but raccoon activity increased with increasing egg predation by ghost crabs, supporting previous research and experimental evidence suggesting ghost crabs can facilitate secondary nest predation by raccoons. This indirect interaction has strong implications for marine turtle conservation, because its strength may increase with increasing ghost crab density, potentially negating the effects of raccoon removal.
Show less - Date Issued
- 2009
- Identifier
- CFE0002667, ucf:48235
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002667
