The main highlight from this research is the finding that exposures of developing killifish embryos to sediments collected from oil-impacted field sites caused developmental abnormalities, including cardiovascular system developmental defects, decreased heart rate, and decreased hatching success. These are effects that are characteristic of crude oil toxicity, and may be predictive of negative effects on population health. To date, our research has linked exposure to oil to the molecular responses that initiate toxic effects and now to negative impacts on the well-being of an important ecological indicator species – our “canary in the coal mine” (see our other study published last year in PNAS). These most recent data represent an important step forward in estimating impacts of the oil spill on resident species in the Gulf of Mexico. Other species that share similar habitats with the Gulf killifish are at risk of similar effects. What is currently unknown is the capacity of affected populations to buffer or absorb the impacts of these types of developmental effects.