Science Serving Maryland's Coasts

Sydney Novak, Franciscan University

Class Year: 

Project Title: 

Understanding the Toxic Effects of Oil Exposure by Measuring DNA Damage in the Blue Crab Callinectes sapidus


Increased use and transport of potentially harmful resources demands a necessary understanding of the toxic effects of the compounds to the surrounding environment. The present study describes the observed toxicity of offshore oil exposure to freshwater invertebrates, likely due to the presence of polycyclic aromatic hydrocarbons (PAHs) present in crude oil. The study was conducted using the basic comet assay protocol to measure the degree of DNA damage and DNA repair capacity of cells exposed to environmentally relevant concentrations of water accommodated fraction (WAF) crude oil ranging from 10 μg/l to 1,000 μg/l. Blue crabs (Callinectes sapidus) were exposed to oil samples taken off the shore of Southern Louisiana, which were then manually weathered. The comet assay technique allowed for rapid analysis of 400 assay samples measuring strand breakage by evaluating tail DNA, tail length and the olive tail moment, a ratio of the two values. Over 130 blue crab larvae were sampled assessing for damage in both the hepatocytes and blood cells. A linear relationship between dosage and DNA damage was expected but minimal significant damage was observed. DNA from blue crab larvae showed little significant impact from acute exposures to WAF crude oil.