Anatomical and Behavioral Assessment of Larval Zebrafish (Danio rerio) Reared in Anacostia River Water Samples

Rapid urbanization, industrial activity, and runoff have all played a role in transforming the Anacostia River from a biologically rich ecosystem to an ecologically threatened environment facing extensive pollution. In recent decades, numerous groups have worked to document and begin to address pollution in the waterway, but few have examined the biological impact of these contaminants. To assess water quality, the current study examined the effects of Anacostia water on early fish development and behavior using zebrafish (Danio rerio). Zebrafish embryos and larvae were reared in water samples collected from the Washington Navy Yard from 0-30dpf (days post fertilization). At 7, 15, 20, and 30dpf, larvae were subsampled for morphological (length, girth, eye diameter, inter-eye distance) and behavioral (angular velocity, total distance traveled, swimming velocity, total activity duration, time immobile, frequency and duration of burst swimming, time at the edge of the dish) assessment. Water samples were processed using gas chromatography-mass spectroscopy (GC-MS) to identify major organic contaminants. Results indicated the presence of 13 bioactive organic contaminants, including siloxane species and hormone derivatives, and accelerated growth and altered swim behaviors in Anacostia-exposed fish after 30 days of exposure. These findings emphasize sublethal but significant impacts of exposure to organic contaminants experienced by fish residing in urban waterways.