Julia Sonn


Changes to stream structure, riparian habitat, and water quality can alter ecosystem dynamics, resulting in an increase in mosquitoes, while weakening populations of amphibians. Therefore, it is necessary to understand how these components are affected by agricultural practices so that mosquito populations can be controlled and aquatic organisms can be protected. In this study, I examined changes in stream structure by measuring geomorphology at three riparian habitats that were anthropogenically impacted to varying degrees. I also compared water quality between the habitats. Mosquitoes and amphibians were surveyed at each riparian habitat, identified to species, and abundances were compared. Stream structure was significantly different at the riparian habitat that did not receive anthropogenic alterations, indicating that erosion had occurred in the agricultural grassland habitat. Nitrates and nitrites accumulated downstream of the agricultural grassland. Mosquito abundances and number of species were similar at all three stream habitats, but the agricultural grassland habitat had a higher percentage of anopheline mosquitoes and greater species evenness. Each riparian habitat was characterized by a specific amphibian species not found at the other stream habitats, indicating a degree of habitat fragmentation. These trends demonstrate that agricultural landscape alterations can alter ecosystem dynamics. Increasing mosquito species diversity and altering amphibian species distributions can create the potential for disease transmission and further weaken a declining vertebrate group.

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