In the wake of the Gulf oil spill, the harmful effects of marine oil spills are obvious. Birds, fish and other marine life can be devastated from a spill, and the ecosystems often take decades to recover. The oil is ingested by some animals, allowing pollutants to enter the food chain, harming fisheries and other industries in the region. Many people don't realize that most oil pollution actually comes from land-based activity. One way or another, oil has seeped into nearly all of Earth's ecosystems.