Explore sulfide springs and their inhabitants

Why is this environment considered extreme?

Sulfide springs are freshwater springs in which the water contains high levels of a gas called hydrogen sulfide. Hydrogen sulfide is extremely toxic for most animals, because it shuts down the energy production in the cells that make up an animal’s body. The levels of hydrogen sulfide in some springs are so high that most animals die upon exposure with minutes.

Where can you find such environments?

Sulfide springs occur world-wide, but few of them are inhabited by fish. We study sulfide springs in the United States, Mexico, Costa Rica, and the Dominican Republic.

What kind of fish live in this environment?

The vast majority of fish that manage to live in sulfide springs below to the family of livebearers (also known as Poeciliidae). Some of the successful members of this family include mollies, guppies, mosquitofish, and swordtails that can be found in pet stores around the world.

How do the fish manage to survive?

Unlike other animals, sulfide spring fish are not affected by the toxic effects of hydrogen sulfide, in part because these species are very efficient in detoxifying the chemical into neutral forms. Fish in sulfide springs also have changed their morphology and reproduction in a way that allows them to be better at taking up oxygen from the environment and conserving energy.