The Combined Effect of Environmental and Anthropogenic Stressors on Fish Health
The 2010 Deepwater Horizon oil spill affected close to 500 miles of coastline, across five states. Considering the size of the disaster, and the variety of habitats affected, great challenges to effectively remediate and protect the entire coastline still remain. Differences in environmental conditions, such as salinity, dissolved oxygen levels and temperature, can have drastic effects on the uptake and effects of contaminants on aquatic organisms. However, there is poor understanding on how aquatic organisms respond and adapt to the combined effects of extreme environmental factors (e.g. hypoxia and high temperatures), typical of highly variable coastal ecosystems, in the presence of contaminants. Thus the development of models that predict impacts of contaminants in these ecosystems is critical in order to prioritize remediation efforts and identify areas of concern.
The proposed project falls under Research Theme 3: “Environmental effects of the petroleum/dispersant system on the sea floor, water column, coastal waters, beach sediments wetlands, marshes, and organisms; and the science of ecosystem recovery”. The objective of this proposal is to study the impact of multiple environmental and anthropogenic stressors on fish development and reproduction. This data will subsequently be used to (1) develop a model that predicts potential population level effects; (2) identify biomarkers which can easily be assessed in the field and are predictive of population level impacts, and (3) identify scenarios (the combination of environmental and anthropogenic stressors) which are most likely to result in population level effects.
More specifically, the aims of the current project are to:
- Determine under which environmental conditions (salinity, oxygen levels and temperature) the effects of petrogenic contaminants are greatest;
- Determine the life-stage most sensitive to exposure;
- Determine the impacts of petrogenic contaminants on reproduction under different environmental scenarios;
- Model observed biological effects and body burdens of petrogenic contaminants in relation to different environmental conditions for prediction of population consequences.
A number of interconnected hypotheses associated with four specific aims will be evaluated. These hypotheses will be tested using both a mixture of environmentally relevant polyaromatic hydrocarbons (PAHs; the group of contaminants of greatest concern within oil), as well as surrogate weathered oil obtained from BP. We will use the gulf killifish (Fundulus grandis) as the model to test our hypotheses. F. grandis is not only an environmental relevant species, but more importantly it is present along the entire Gulf of Mexico coast allowing it to serve a sentinel for evaluating impacts.
In year 1 a series of high throughput embryo tests will be conducted using F. grandis to determine the environmental conditions under which embryos are most sensitive to PAH exposure (Aim 1). Based on these results, follow-up experiments with early-life stages (Aim 2) and adults (Aim 3) will be conducted testing the combined effects of petrogenic contaminants and stressful environmental conditions on F. grandis survival, growth and reproduction. This data will then be used in a stochastic population model that will aid in the identification and prioritization of areas of concern based on environmental variables (Aim 4).
Ultimately, this project will result in timely information on the impact of different environmental conditions on fish development and reproduction. Moreover, it will use this data and integrate it into a population model which can be used by fellow scientists, policy makers and the public to help identify areas of concern.