Current Search: UWF Theses and Dissertations (x) » Darby, Philip C. (x)
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- Title
- MOVEMENT AND BEHAVIOR OF THE SAND DOLLAR, MELLITA TENUIS.
- Author
- Earls, Ashley Brianna, Pomory, Christopher M., Darby, Philip C., Janosik, Alexis M., University of West Florida
- Abstract/Description
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Mellita tenuis occurs in large aggregations numbering in the tens per m2. Due to their high density they are considered major bioturbators of their environment. This investigation of ecological factors affecting their movement and behavior has provided a deeper understanding of the basic biology and ecological connectivity of this species. In this study, M. tenuis was placed in an enclosure under varying treatments and video recorded. The recordings were analyzed for activity, movement,...
Show moreMellita tenuis occurs in large aggregations numbering in the tens per m2. Due to their high density they are considered major bioturbators of their environment. This investigation of ecological factors affecting their movement and behavior has provided a deeper understanding of the basic biology and ecological connectivity of this species. In this study, M. tenuis was placed in an enclosure under varying treatments and video recorded. The recordings were analyzed for activity, movement, covering, distance travelled, and velocity. Contrary to existing literature, which has been primarily based on qualitative observations, there was no significant diel rhythm found for any of the variables studied among time of day treatments. Neither feeding history nor predator presence had significant effects, however, size was found to affect covering and velocity, with large individuals moving at a rate nearly two times faster and covered significantly less often than small individuals. Density differences resulted in a change in rotational activity, with individuals in low densities more active than those in high densities. The size of other individuals in the immediate area did not have a significant effect on any of the variables, although a higher sample size is recommended for borderline results.
Show less - Date Issued
- 2016
- Identifier
- WFE0000530, uwf:61247
- Format
- Document (PDF)
- Title
- QUANTIFYING HABITAT AND APPLE SNAIL (POMACEA PALUDOSA) DENSITY EFFECTS ON PREY AVAILABILITY TO SNAIL KITES (ROSTRHAMUS SOCIABILIS PLUMBEUS).
- Author
- Coppola, Philip Michael, Darby, Philip C., Jeffrey, Wade H., Meyer, Kenneth D., University of West Florida
- Abstract/Description
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Everglades restoration efforts rely on quantitative data when modelling the effects of management on endangered wildlife populations. The focus of this study was to quantify the influence of environmental factors on Florida apple snail (Pomacea paludosa) availability to snail kites (Rostrhamus sociabilis plumbeus) within the Everglades. A mesocosm study with observations of live apple snails was performed within Everglades wetlands to determine the influence of water depth, water temperature,...
Show moreEverglades restoration efforts rely on quantitative data when modelling the effects of management on endangered wildlife populations. The focus of this study was to quantify the influence of environmental factors on Florida apple snail (Pomacea paludosa) availability to snail kites (Rostrhamus sociabilis plumbeus) within the Everglades. A mesocosm study with observations of live apple snails was performed within Everglades wetlands to determine the influence of water depth, water temperature, dissolved oxygen, and emergent vegetation structure on the proportion of apple snails available to foraging snail kites. In addition, a study analyzing snail kite prey species (native P. paludosa versus exotic P. maculata) and size preference was performed. The proportion of apple snails available to kites was most influenced by water depth and temperature, where warm, shallow water contained the highest proportion of snails available. Emergent vegetation did not affect snail surfacing behavior; however, it did influence the relative detectability of snails. Snail kites preferentially consumed intermediate-sized snails and showed no species preference. This study supports the recommendation that demographic modeling of Everglades-dependent wildlife should incorporate the most ecologically-pertinent parameters. Estimates of snail availability can be used to link two thus far-independent simulation models for snail kite and apple snail populations.
Show less - Date Issued
- 2016
- Identifier
- WFE0000552, uwf:61223
- Format
- Document (PDF)
- Title
- RECRUITMENT DYNAMICS AND OTOLITH CHEMICAL SIGNATURES OF JUVENILE GRAY SNAPPER, LUTJANUS GRISEUS, AMONG WEST FLORIDA ESTUARINE AND COASTAL MARINE ECOSYSTEMS.
- Author
- Lounder, Cecelia, Patterson, William F., Darby, Philip C., McBride, Richard S., University of West Florida
- Abstract/Description
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A hierarchical approach to examine nursery function of coastal systems was tested for gray snapper, Lutjanus griseus. Juveniles were sampled with trawls and seines in four regions along west Florida. The first two tiers of habitat evaluation showed that seagrass was a significant variable for presence/absence and density of gray snapper (Binomial GLM; p
Show moreA hierarchical approach to examine nursery function of coastal systems was tested for gray snapper, Lutjanus griseus. Juveniles were sampled with trawls and seines in four regions along west Florida. The first two tiers of habitat evaluation showed that seagrass was a significant variable for presence/absence and density of gray snapper (Binomial GLM; p < 0.001, Delta Lognormal GLM; p = 0.002). Significant differences in growth rates were observed in 2007 (ANCOVA test for equal slopes; p < 0.001) but not 2006, driven by fastest growth in the Southwest region and slowest in the Big Bend region. Region-specific natural tags from otolith chemistry were derived from element:Ca ratios (Ba:Ca, Li:Ca, Mg:Ca, Mn:Ca, and Sr:Ca) and carbonate stable isotopes values (13C and 18O). Significant differences were found among study regions and between sampling years (MANOVA Pilia's trace; p < 0.001 for both effects). Cross validated classification accuracies using four regions were 77.9% in 2006, 85.0% in 2007, and 76.3% when years were modeled jointly. Using three regions raised classification success to 82.6% in 2006, 92.3% in 2007, and 83.3% when years were modeled jointly. Subsequent studies may employ tags based on otolith chemical signatures to estimate nursery sources of adults.
Show less - Date Issued
- 2009
- Identifier
- WFE0000156, uwf:60791
- Format
- Document (PDF)
- Title
- REEF FISH COMMUNITY STRUCTURE AT UNPUBLISHED ARTIFICIAL REEF SITES OFF NORTHWEST FLORIDA: IMPLICATIONS FOR HARVEST REFUGIA.
- Author
- Dance, Michael Allen, Patterson, William F., Darby, Philip C., Lindberg, William J., University of West Florida
- Abstract/Description
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Reef fish community structure was estimated from video collected at unpublished artificial reef sites (n = 27) located between 15 and 20 miles south of Pensacola, Florida. Quarterly sampling trips were conducted between fall 2004 and summer 2006. Video sampling was performed with a remotely operated vehicle (ROV) equipped with a laser scaler that was used to estimate fish size. Tagging also was conducted at a subset (n = 9) of reef sites to examine species-specific site fidelity and movement....
Show moreReef fish community structure was estimated from video collected at unpublished artificial reef sites (n = 27) located between 15 and 20 miles south of Pensacola, Florida. Quarterly sampling trips were conducted between fall 2004 and summer 2006. Video sampling was performed with a remotely operated vehicle (ROV) equipped with a laser scaler that was used to estimate fish size. Tagging also was conducted at a subset (n = 9) of reef sites to examine species-specific site fidelity and movement. Results indicate that reef communities are dynamic in nature as significant changes occurred in fish assemblages and the reef-attached fouling community during the study. Number of fish species and individuals present increased over time, while evenness and the Shannon-Weiner diversity index decreased. Reefs were characterized by large abundances of small red snapper (< 9% above the legal size limit of 406 mm) which increased in abundance, along with other lutjanids, throughout the study, while grouper abundances decreased. Tagging data demonstrated that red snapper exhibited the lowest site fidelity and most movement (mean distance = 27.2 km) among tagged fishes. Overall, study results suggest even fishes observed at unreported artificial reef sites may suffer significant fishing mortality if they move among fished and unfished areas.
Show less - Date Issued
- 2008
- Identifier
- WFE0000106, uwf:60844
- Format
- Document (PDF)
- Title
- TEMPORAL DIFFERENCES IN NITROGEN FIXATION RATES WITHIN SEDIMENTS COLONIZED BY SUBTROPICAL SEAGRASS SPECIES, THALASSIA TESTUDINUM AND HALODULE WRIGHTII.
- Author
- Capps, Rachel Elizabeth, Caffrey, Jane M., Darby, Philip C., Lepo, Joe Eugene, University of West Florida
- Abstract/Description
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Seagrasses are widely distributed across the globe and provide many ecological services. Thalassia testudinum and Halodule wrightii are the dominant taxa in Northwest Florida. Primary productivity in coastal ecosystems is often limited by availability of bioavailable nitrogen. Nitrogen fixation is a microbially mediated process that converts N2 to bioavailable forms. This study measured nitrogen fixation and environmental parameters in unvegetated areas and seagrass colonized sediments for...
Show moreSeagrasses are widely distributed across the globe and provide many ecological services. Thalassia testudinum and Halodule wrightii are the dominant taxa in Northwest Florida. Primary productivity in coastal ecosystems is often limited by availability of bioavailable nitrogen. Nitrogen fixation is a microbially mediated process that converts N2 to bioavailable forms. This study measured nitrogen fixation and environmental parameters in unvegetated areas and seagrass colonized sediments for one year. Porewater nutrient ratios in sediments colonized by seagrass suggest that nitrogen is the limiting nutrient. Conversely, unvegetated sediments show phosphorus limitation. Nitrogen fixation rates were higher in vegetated areas compared to adjacent unvegetated areas. In unvegetated sediments, increased mineralization results in increased nutrients and energy sources for sulfate reducing bacteria which fix nitrogen. In H. wrightii colonized sediments, nitrogen fixation was driven by decreased availability of nitrogen relative to phosphorus. In T. testudinum colonized sediments, nitrogen fixation was higher during winter. Organic matter supply may be a controlling factor in all three substrate types albeit the mechanism driving nitrogen fixation is slightly different. During June 2016, July 2016, and September 2016, nitrogen fixation provided 8.5%, 1.0%, and 1.0%, respectively, of T. testudinum nitrogen demand. Annually, nitrogen fixation provides 1.3% and 2.9% of the nitrogen demand for T. testudinum and H. wrightii, respectively. Nitrogen fixation was an important source of nitrogen during periods of senescence and dormancy when organic matter content was higher and seagrasses obtain the majority of their nitrogen from the sediments.
Show less - Date Issued
- 2017
- Identifier
- WFE0000571, uwf:61205
- Format
- Document (PDF)
- Title
- THE ARTIFICIAL REEF EFFECT OF WORLD WAR II ERA SHIPWRECKS IN THE NORTHERN GULF OF MEXICO.
- Author
- Morris, Nicole Marie Brown, Patterson, William F., Darby, Philip C., Snyder, Richard A., University of West Florida
- Abstract/Description
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Deepsea fishes and their associated habitats have not been well studied in the northern Gulf of Mexico (Gulf). Furthermore, little is know about whether fishes in the deep Gulf utilize shipwrecks as artificial reef habitat. The objective of this study was to examine the utilization of shipwrecks as habitat by fishes across a depth gradient in the northern Gulf. I examined community structure, diet, trophic structure using stable isotope values (13C, 15N, and 34S), and age of fishes associated...
Show moreDeepsea fishes and their associated habitats have not been well studied in the northern Gulf of Mexico (Gulf). Furthermore, little is know about whether fishes in the deep Gulf utilize shipwrecks as artificial reef habitat. The objective of this study was to examine the utilization of shipwrecks as habitat by fishes across a depth gradient in the northern Gulf. I examined community structure, diet, trophic structure using stable isotope values (13C, 15N, and 34S), and age of fishes associated with six World War II era shipwrecks ranging in depth from 87 to 1,964 m. Statistical analysis of community structure estimates revealed significant differences existed among wreck sites (ANOSIM: p 0.001) and among sample locations within sites (ANOSIM: p 0.001). At the three shallowest sites, reef- or structure-associated fishes were predominant over wreck sites. Fish communities over deep wrecks were similar to those away from wrecks and consisted mostly of halosaurs (Family: Halosauridae), cusk eels (Order: Ophidiiformes), grenadiers (Family: Macrouridae), and eel (Family: Anguilliformes) species, listed in order from highest to lowest relative abundance. Diet of fishes was determined by analysis of gut contents (n = 107) and trophic position was further clarified by analysis of muscle stable isotope values (n = 79). Results revealed a range of trophic levels and sources of production as benthic, pelagic, or chemosynthetic. At the two shallowest sites, 13C and 15N values among fishes indicated a range in feeding from planktivores to piscivores, and 34S values indicated a range in benthic versus pelagic prey. Stable isotope values among fishes at the third shallowest site indicated little difference in trophic levels and a pelagic source of production. At the three deepest sites, 13C and 15N values indicated feeding at middle trophic levels, and 34S values indicated a pelagic source of production. A total of 97 otolith sections (84 adults and 13 juveniles) were examined. On the two shallowest wreck sites, fish tended to be larger at age and younger overall than fishes on deeper wreck sites. Results from this study provide insight into the ecological function of shipwrecks as large artificial reefs along a depth gradient. The artificial reef affect of shallow wreck sites was apparent, but for shipwrecks below 1,500 m, no artificial reef effect was observed for fishes.
Show less - Date Issued
- 2007
- Identifier
- WFE0000067, uwf:60700
- Format
- Document (PDF)
- Title
- THE EFFECT OF SHRIMP DENSITY AND ARTIFICIAL SEAGRASS DENSITY ON GROWTH AND PROXIMATE BODY COMPOSITION OF THE BROWN SHRIMP, FARFANTEPENAEUS AZTECUS (IVES, 1891) (CRUSTACEA:MALACOSTRACA: DECAPODA: PENAEIDEA).
- Author
- Ren, Alexander Kyung Joo, Pomory, Christopher M., Dantin, Darrin D., Darby, Philip C., University of West Florida
- Abstract/Description
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Complex habitats benefit organisms by providing refuge from predators, foraging, and stress reduction. Juveniles are particularly vulnerable and rely on complex habitats as nurseries. Many studies have assigned nursery value to habitats based on juvenile abundances, rather than growth and recruitment to adult populations. Nearly all such studies have compared habitat types, rather than within habitat variation. The purpose of this study was to determine the potential value of different...
Show moreComplex habitats benefit organisms by providing refuge from predators, foraging, and stress reduction. Juveniles are particularly vulnerable and rely on complex habitats as nurseries. Many studies have assigned nursery value to habitats based on juvenile abundances, rather than growth and recruitment to adult populations. Nearly all such studies have compared habitat types, rather than within habitat variation. The purpose of this study was to determine the potential value of different seagrass, submerged aquatic vegetation (SAV), densities as well as shrimp densities to growth of juvenile brown shrimp, Farfantepenaeus aztecus (Ives, 1891). Experiments in tanks examined effects of non-vegetated bottom (NVB) and artificial SAV densities and different shrimp densities on growth. Measurements included total length, dry weight, and body composition of protein, lipid, and carbohydrate. Presence and density of artificial SAV density did not result in greater growth or changes in body composition; however, individual growth and carbohydrate reserves decreased significantly with increasing shrimp density. While individual growth decreased, total biomass produced was greatest in tanks with high shrimp densities. While the value of SAV should not be reduced, it appears that the value of NVB to juvenile brown shrimp may have been ignored by previous studies.
Show less - Date Issued
- 2011
- Identifier
- WFE0000291, uwf:60964
- Format
- Document (PDF)
- Title
- THE INFLUENCE OF A GRADIENT IN HABITAT STRUCTURE ON APPLE SNAIL (POMACEA PALUDOSA) DEMOGRAPHY AND SNAIL KITE (ROSTRHAMUS SOCIABILIS PLUMBEUS) FORAGING.
- Author
- Wight, Bethany Rose, Darby, Philip C., Meyer, Kenneth D., Caffrey, Jane M., University of West Florida
- Abstract/Description
-
Everglades restoration efforts focus on improving habitats that support associated endangered wildlife. This study focused on the influence of habitat structure and prey density on the endangered Florida snail kite and the kite's exclusive prey, the Florida apple snail. Snail densities and egg production were estimated across a habitat gradient, from the sawgrass ecotone to wet prairie habitat. Kite foraging was examined as a function of habitat and snail densities at varying spatial scales....
Show moreEverglades restoration efforts focus on improving habitats that support associated endangered wildlife. This study focused on the influence of habitat structure and prey density on the endangered Florida snail kite and the kite's exclusive prey, the Florida apple snail. Snail densities and egg production were estimated across a habitat gradient, from the sawgrass ecotone to wet prairie habitat. Kite foraging was examined as a function of habitat and snail densities at varying spatial scales. Snail densities were relatively low, which may be attributed to a depensation effect and the distribution of snails among habitat types within a site was highly variable. Egg densities were greater along the sawgrass ecotone; however, egg abundance in wet prairie contributed more to total egg production. Kite foraging data suggested prey density variation in small patches within a site was not a good predictor of where kites concentrated their foraging. However, as scale increased (sites within a wetland, and between wetlands), snail density may explain kite occupancy. These results support the idea that restoration efforts should focus on creating habitats with a range of characteristics (sawgrass, wet prairie, and slough habitats) at varying temporal and spatial scales to support kite foraging and apple snail populations.
Show less - Date Issued
- 2013
- Identifier
- WFE0000378, uwf:61025
- Format
- Document (PDF)