As a rule, we think that pollution is something that primarily affects an individual then and there in the face of a pollution source. But what if the effects of exposure to, for example, crude oil can be traced across generations - that the exposure to which an individual has been exposed to can have measurable effects on, for example, fertility in their children and grandchildren who were not even thought of when the exposure occurred? What might this mean for the sustainable use and management of fish stocks?
Although we know that fish embryos and larvae are extremely sensitive to oil spills upon direct exposure, we know much less about the sensitivity of adult fish in important life phases such as the reproductive period. The most sensitive life stage of a species is not necessarily the most sensitive stage to population viability. So, investigating the sensitivity of oil exposure to reproducing adults, and the potential consequence to next generations is highly important to evaluate the adequacy of current impact and risk assessment models.
Toxigen will combine advanced chemical and molecular analytical approaches to elucidate the toxicity mechanisms of components of crude oil and effects on the reproductive success of fishes and subsequent survival and health of successive generations. The project asks: does oil exposure disrupts egg and milt production in adults? Are toxic compounds transferred from parents to offspring to cause toxic effects? Does crude oil induce effects that can be inherited over multiple generations?
Our ambition is to link molecular changes to compounds taken up by the parent fish and changes in reproductive success as well as health in first, second and third generation of fish. Ultimately, in an assessment report to stakeholders, the project will present an analysis of new results and whether these findings are of such concern that they warrant further investigations and the revision of existing risk and impact assessment tools.
A fundamental and enduring challenge for ecosystem managers developing risk and impact assessment tools is to predict the extent of impact that spilled oil can have on the immediate fish populations and on future generations. Modelling approaches are important tools for these assessments, but they currently suffer from two major shortcomings: 1) the failure to acknowledge that effects can be transferred through several generations and 2) the assumption that a small group of toxic compounds, polycyclic aromatic hydrocarbons, can be used as chemical proxy for exposure to complex petroleum mixtures. Emerging understanding within petroleum ecotoxicology now suggests that model outputs lack robustness. Up until now studies have not been able to determine the effects over multiple generations, and to properly identify the causative agents within petroleum. ToxiGen is an interdisciplinary study that will determine the effects and toxic mechanisms of petroleum on the reproductive success of fishes and subsequent generations. Our ambition is to identify the compounds responsible for alterations in reproductive success in adults and survival and fitness of the progeny. We will work with Atlantic cod and polar cod that are of high ecological and commercial importance, respectively. Zebrafish will be used for high-risk and generational experiments. We will work at the frontier of analytical chemistry to characterize the toxic fractions of petroleum. To disentangle mechanisms of toxicity, novel methods such as micro-injecting compounds into eggs will be used. We will combine different approaches to identify new biomarkers of exposure and effects. The new knowledge will then be integrated into reproductive adverse outcome pathways to be available through an internationally harmonized knowledgebase. Ultimately, ToxiGen will provide environmental managers with knowledge and data for models, and methods to detect and monitor the presence and impact of these complex mixtures in situ.