The Toxicity of Weathered Oil on an Oil Resistant Diatom Species

This project investigated the toxicity of weathered oil on an oil resistant diatom species, Phaeodactylum tricornutum. Most oil toxicology studies focus on the use of fresh oil, while phytoplankton that live in the euphotic zone are exposed to photo-oxidized oil. The main research questions focused on the toxicity of weathered oil in comparison to fresh oil and how P. tricornutum responds to this form of pollution. These and related questions are of utmost importance when discussing the lasting effects of an oil spill event on primary producers. These questions were explored through batch-culture experiments, where cultures of P. tricornutum were exposed to fresh (WAF) and weathered oil (PhotoWAF) in the form of a water accommodated fraction of oil. We found that photo-oxidized oil targets the cell’s ability to harvest light and reduces relative electron transport rates after the initial exposure. In addition, the observed negative physiological effects impacted cell growth throughout the experiment. Our data shows that photo-oxidized oil negatively effects the physiology and growth of P. tricornutum, specifically targeting the cell’s light harvesting capabilities. Thus, using photo-oxidized oil is an important consideration for oil toxicity studies when simulating real life conditions versus laboratory settings