Crude oil – which is used to make gasoline, fuel oils, asphalt, and some plastic products – can be toxic for many coastal and marine animals and plants when spilled in the environment. That’s why oil spills in the ocean can be a problem. We wanted to know what impact a large spill might have on fiddler crabs. These small crabs play a big role in their coastal salt marsh ecosystem, so if something harms them, other parts of the ecosystem could suffer.
We analyzed data collected by five different studies over a 4-year period in the Gulf of Mexico after the Deepwater Horizon oil spill. We saw that the oil spill reduced the number of fiddler crabs, likely killed many of them directly, and changed the species of fiddler crabs present in the marsh for years after the spill. Changes in fiddler crab populations may have affected other parts of the ecosystem, including marsh plant growth, soils, and predators of fiddler crabs.