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UT Knoxville FWF 250 - Global Amphibian Declines
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FWF 250 1st Edition Lecture 14Outline of Last Lecture I. Zoos and Conservation – Maria Spriggs, DVMA. ZoosB. Oil SpillsC. Wildlife RehabilitationOutline of Current Lecture I. Global Amphibian Declines – Matthew GrayA. Status of AmphibiansB. SusceptibilityC. ImportanceD. CausesCurrent Lecture Global Amphibian Declines- Status of Amphibianso There are three orders of amphibians: Anura (frogs/toads), Caudata (salamanders/newts), and Gymnophiona (caecilians). o We are currently in a worldwide amphibian population decline. Some people even believe that we are amidst the sixth mass extinction. An average of 3% annual decline exists.o Frogs usually go through a tad pole stage during their life cycle; however, one species does not. This species is known as the gastric-brooding frog. This frog swallows its eggs and shuts off its digestive processes. Unfortunately, they are extinct.o IUCN keeps up with the status of amphibian populations. About 30% of amphibians are experiencing a decline. This includes about 30% of frogs/toads and 50% of salamanders/newts.o Amphibians are the most imperiled vertebrate class. However, freshwater turtlesare the only ones declining faster.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is bestused as a supplement to your own notes, not as a substitute.o Tennessee has the most species of salamanders. Salamanders tend to be lungless and breathe through their skin.o Two salamander species and 34 species of anurans are considered extinct. o 54 species of amphibians haven’t been seen in 5-40 years, mostly in Latin America. Therefore, these will soon be termed extinct.o In the United States, there are two species of amphibians, frog and salamander, that are extinct. 10 species are endangered, 9 species are threatening, and 5 species are awaiting. o Most of the declines are in the western U.S. In TN, the cave salamander is declining; 26 species (about 30%) are of concern. - Susceptibilityo Amphibians are exothermic vertebrates with a biphasic life cycle. o They have a low ability to move. Their vagility is low to about 1 km.o Transmission of parasites occurs more often and easier in water.o The temperature of the environment also affects their susceptibility.o Amphibians take up water (osmoregulation) and oxygen (respiration) through their skin. The skin must remain moist. Because of this, they tend to absorb harmful compounds readily through their skin.o Desiccation is a lifelong struggle for amphibians. They can live to around 10 years.- Importanceo Organisms above and below the amphibians rely on them. Amphibians are very important to the ecosystem.o Amphibians are indicators since they are sensitive to environmental changes.o A huge amount of biomass exists.o They ear pest and insect populations. o Amphibians are also utilized for medicinal purposes. Some frogs give off poison that is 20 times stronger than morphine.- Causes1. Habitat Destruction/Degradation Hypothesiso Obvious: agricultural practices; urban development (54% loss of wetlands due to draining/filling); deforestation (a clear cut forests takes 30 years to fully recover)o Not obvious: sedimentation; altered hydroperiods; wildlife management (burning/mowing)2. Chemical Pollution Hypothesiso Point source: pollution originating from one point. Effluent is from organic/industrial waste. Thermal is from electric plants.o Non-point source: pollution originating from multiple points.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Chemical and effects:- nitrates and ammonia: direct morality and reduce growth- organophosphate insecticides: malformations and altered behavior- atrazine: herbicide- various oils and compounds: affect respiration3. Introduced Predators and Competitors Hypothesiso Predators: fish (eat everything); bullfrogs (eat everything but adults); fire ants(eat metamorphs)o Competitors: frogs; bait; mosquito fish; crawfish (predator of eggs also)4. Commercial Exploitation Hypothesiso This is a major concern in Southeast Asia.o They are captured for consumption and the pet industry.o Removal: 200 million exported annually from Asia; 70 million exported annually from Indiao Release: exotics or captive-reared specimens; 9 million frogs shipped from biological supply companies in United States.5. Climate Change Hypothesiso It is the anthropogenic increase of ambient temperatures via the accumulation of greenhouse gases.o The affect depends on the severity of the weather.o It causes direct alteration of habitat and affects distribution and breeding.6. UV-B Radiation Hypothesiso Ozone depletion7. Acid Precipitation Hypothesiso Emissions of nitrogen oxides and sulfur dioxide8. Pathogenic Hypothesis – Chytrid Funguso This fungus attacks during the adult stage. It can cause epidermal hyperplasia, paralyzed body, and heart attacks.9. Pathogenic Hypothesis – Parasiteso Trematodes target limb development by preventing growth or splitting the limbs. High nitrogen sites are beneficial for this parasite.10. Pathogenic Hypothesis – Ranavirus o Signs of this disease include ulcerations and hemorrhaging. It is similar in concept to Ebola. Ranavirus causes death in as quick as three days.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a


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UT Knoxville FWF 250 - Global Amphibian Declines

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