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Journal of Wildlife Management 01/2013; · 1.52 Impact Factor
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ABSTRACT: Tree islands—small, wetland forest communities imbedded in a matrix of freshwater marsh—characterize Arthur R. Marshall Loxahatchee National Wildlife Refuge in South Florida. The establishment and spread of invasive exotic plant species were hypothesized to alter tree-island communities and prolong recovery times from hurricane disturbances. During the fall of 2004, two hurricanes, Frances and Jeanne, caused damage to these tree islands. We examined the spatial extent of damage to tree islands and tree species across the Refuge by sampling 74 islands. Each tree island was assigned an overall damage rating based on both the openness of the canopy and the type and quantity of damage received. Distance from the eye-wall of the hurricanes, tree-island size, average tree height on the island, and relative abundance of invasive exotic plants were examined as predictors of damage. Over 85% of the sampled tree islands had damage, with most of the damage occurring in the center of the Refuge. Most tree islands were found to have moderate damage, (i.e., snapped large branches and less than 50% canopy cover removed). Persea palustris (swamp bays) had more snapped trunks than Ilex cassine (dahoon holly) and Myrica cerifera (wax myrtle). Islands with larger trees had heavier damage than islands with shrubs or smaller trees. Fifty-eight percent of the tree islands sampled had either Lygodium microphyllum (lygodium) and/or Melaleuca quinquenervia (melaleuca). The only island with severe damage had abundant lygodium that appeared to have caused the entire canopy to collapse. These hurricanes present a unique opportunity to investigate recovery patterns of tree islands in an ecosystem impacted by invasive exotics. They also provide an opportunity to examine patterns of spread and recruitment of lygodium and melaleuca.
Southeastern Naturalist 11/2006; · 0.49 Impact Factor
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ABSTRACT: The Pig Frog (Rana grylio) is an aquatic frog that is an abundant component of the Everglades ecosystem. South Floridians recreationally and commercially hunt pig frogs in marshes throughout Water Conservation Areas (WCA) and Big Cypress National Preserve (BCNP) in South Florida. Most of these areas are under fish consumption advisories because of high levels of methylmercury present in game fish tissues. It is important to understand how mercury is distributed throughout Pig Frog populations because their consumption from certain areas may present a risk to human health. We sampled 88 pig frogs along a north-south transect through the Florida Everglades. There were substantial differences in total mercury (THg) concentrations from leg muscle tissue among sites. Total mercury in frog leg tissue was highest from areas protected from harvest in Everglades National Park (ENP), with a maximum concentration of 2051 ng/g wet mass. The THg levels in R. grylio leg tissue from most harvested areas are below Federal advisory limits. However, many pig frogs collected near Frog City, and one from WCA 3B and 3AN, harvested sites, had THg levels above the USEPA 0.3 mg/kg Fish Tissue Residue Criterion. Spatial patterns in the mercury found among pig frogs were similar to those of other wildlife species from the Everglades. We found frogs to have high THg levels in areas where alligators and mosquito fish also have high THg. THg in ENP frogs had an exponential relationship to SVL, we found no other relationship in frogs from other sites. Our data suggests that pig frogs should not be harvested or consumed from sites that exceed federal limits.
Science of The Total Environment 07/2005; 345(1-3):51-9. · 3.29 Impact Factor
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Cristina A Ugarte
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ABSTRACT: This study investigated how harvest and water management affected the ecology of the Pig Frog, Rana grylio . It also examined how mercury levels in leg muscle tissue vary spatially across the Everglades. Rana grylio is an intermediate link in the Everglades food web. Although common, this inconspicuous species can be affected by three forms of anthropogenic disturbance: harvest, water management and mercury contamination. This frog is harvested both commercially and recreationally for its legs, is aquatic and thus may be susceptible to water management practices, and can transfer mercury throughout the Everglades food web. This two-year study took place in three major regions: Everglades National Park (ENP), Water Conservation Areas 3A (A), and Water Conservation Area 3B (B). The study categorized the three sites by their relative harvest level and hydroperiod. During the spring of 2001, areas of the Everglades dried completely. On a regional and local scale Pig Frog abundance was highest in Site A, the longest hydroperiod, heavily harvested site, followed by ENP and B. More frogs were found along survey transects and in capture-recapture plots before the dry-down than after the dry-down in Sites ENP and B. Individual growth patterns were similar across all sites, suggesting differences in body size may be due to selective harvest. Frogs from Site A, the flooded and harvested site, had no differences in survival rates between adults and juveniles. Site B populations shifted from a juvenile to adult dominated population after the dry-down. Dry-downs appeared to affect survival rates more than harvest. Total mercury in frog leg tissue was highest in protected areas of Everglades National Park with a maximum concentration of 2.3 mg/kg wet mass where harvesting is prohibited. Similar spatial patterns in mercury levels were found among pig frogs and other wildlife throughout parts of the Everglades. Pig Frogs may be transferring substantial levels of mercury to other wildlife species in ENP. In summary, although it was found that abundance and survival were reduced by dry-down, lack of adult size classes in Site A, suggest harvest also plays a role in regulating population structure.
ProQuest ETD Collection for FIU.
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Cristina A Ugarte
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ABSTRACT: Most ethnopharmacological studies overlook food plants, yet many edible plants, also have medicinal value. I documented plants that are used as both food and medicine by the Totonac of Zapotitlan de Mendez, Mexico and recorded the presence of selected secondary compounds, and physical characteristics in these plants. Photoactivity, antimicrobial, and antifungal assays also were performed. The presence of these properties were compared among food/medicine plants, food, medicinal, and randomly selected plants. I predicted that a higher percentage of medicinal plants would contain the secondary compounds, physical characteristics, and bioactivity compared to the other groups. Phenolics and cyanogenic glycosides in the medicinal group were significantly greater than in the food/medicine group. The food plants did not differ greatly from the medicinal plants. This research indicates that including food plants in ethnomedical studies could provide a more complete knowledge of peoples therapeutic resources and practices.
ProQuest ETD Collection for FIU.
