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Effects of Ultraviolet Radiation (UVR) Induced DNA Damage and Other Ecological Determinants on cryptosporidium Parvum, Giardia Lamblia, and Daphnia spp. in Freshwater Ecosystems
Connelly, Sandra J.

2007, Doctor of Philosophy, Miami University, Zoology.

Freshwater ecosystems are especially susceptible to climatic change, including anthropogenic-induced changes, as they are directly influenced by the atmosphere and terrestrial ecosystems. A major environmental factor that potentially affects every element of an ecosystem, directly or indirectly, is ultraviolet radiation (UVR). UVR has been shown to negatively affect the DNA of aquatic organisms by the same mechanism, formation of photoproducts (cyclobutane pyrimidine dimers; CPDs), as in humans. First, the induction of CPDs by solar UVR was quantified in four aquatic and terrestrial temperate ecosystems. Data show significant variation in CPD formation not only between aquatic and terrestrial ecosystems but also within a single ecosystem and between seasons. Second, there is little quantitative data on UV-induced DNA damage and the effectiveness of DNA repair mechanisms on the damage induced in freshwater invertebrates in the literature. The rate of photoproduct induction (CPDs) and DNA repair (photoenzymatic and nucleotide excision repair) in Daphniafollowing UVR exposures in artificial as well as two natural temperate lake systems was tested. The effect of temperature on the DNA repair rates, and ultimately the organisms’ survival, was tested under controlled laboratory conditions following artificial UVB exposure. The results of these studies suggest a significant interaction of UVR and temperature on individual survival and ultimately population dynamics in freshwater systems.


Lastly, freshwater human pathogens have negative effects ranging from gastrointestinal distress in otherwise healthy individuals to death in the immunocompromised and elderly. The control of infectious pathogens in water treatment is imperative. The abiotic and biotic environmental stressors of human pathogens are not well understood. Herein, solar radiation and artificial UVB are shown to significantly decrease the infectivity of Cryptosporidium parvum in vitro. The generalist filter feeder, Daphnia pulicaria, was shown to have significant effects on the viability, excystation, and infectivity of both Cryptosporidium parvumand Giardia lambliaunder laboratory-controlled conditions. Both of these studies have significant implications for the natural control and potable water pretreatment approaches to human pathogen control.


Craig Williamson (Advisor)
141 p.

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Connelly, S. (2007). Effects of Ultraviolet Radiation (UVR) Induced DNA Damage and Other Ecological Determinants on cryptosporidium Parvum, Giardia Lamblia, and Daphnia spp. in Freshwater Ecosystems. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Connelly, Sandra. "Effects of Ultraviolet Radiation (UVR) Induced DNA Damage and Other Ecological Determinants on cryptosporidium Parvum, Giardia Lamblia, and Daphnia spp. in Freshwater Ecosystems." Electronic Thesis or Dissertation. Miami University, 2007. OhioLINK Electronic Theses and Dissertations Center. 31 Jul 2015.

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Connelly, Sandra "Effects of Ultraviolet Radiation (UVR) Induced DNA Damage and Other Ecological Determinants on cryptosporidium Parvum, Giardia Lamblia, and Daphnia spp. in Freshwater Ecosystems." Electronic Thesis or Dissertation. Miami University, 2007. https://etd.ohiolink.edu/

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