For over 100 years, the presence of coliform bacteria in water has been used as environmental risk indicators for the occurrence of human pathogens (Salmonella, enteric viruses, etc.). Although these measurements typically are used to protect humans from potential exposure to toxins, little has been researched about the effect on organisms that live in these waters. Our current study utilizes a long-term water monitoring program within the Appomattox River watershed of south-central Virginia, as it examines the effect of raw water containing varying bacteria levels on the first 72 hours of aquatic vertebrate development, using a zebrafish model. Water samples were obtained from a variety of freshwater collection sites both considered ‘clean’ and ‘impaired’ by the VA Department of Environmental Quality (‘impaired’ includes >238 fecal coliforms/100mL across multiple samplings). Other physical parameters were similar between sample sites. By measuring the presence of fecal indicator bacteria, the relative number of pollutants can be assayed. By comparing zebrafish embryos raised in clean versus impaired water sources, the effect on muscle development and physiology was examined. qRT-PCR analysis and in situ hybridizations were performed to identify altered expression levels of genes critical for proper muscle development. Furthermore, we examined how this misexpression of muscle genes altered the swimming physiology of the young fish. One key early muscular behavior in 4-week-old fish was examined - a startle response that includes the fish making a C-shaped bend to swim away from predators (C-starts). We examined the effects of 'impaired' water on C-starts and have identified differences in muscle physiology due to the impaired waters. This experiment can ultimately be used to trace the effects of impaired water sources initially on gene expression levels within the muscles of the fish embryo, and then ultimately that effect on the physiology of muscle movement.
Hayek, Cecily, "The Effects of Impaired Water on Zebrafish Muscle Development and Startle Responses" (2022). Longwood Senior Theses. 11.