STILLWATER, Okla. — A fish in Mexico can survive in water that would be toxic to most other organisms on the planet, and an Oklahoma State University researcher hopes to find out how.

Michael Tobler, an OSU zoology professor, was recently awarded a three-year $481,000 grant from the National Science Foundation to study the evolution of fish in the presence of hydrogen sulfide, a gas that, even at low concentrations, would be lethal for most animals.

During the study, Tobler will be working with shortfin mollies, a small live-bearing fish that is a close relative of the mollies found in American pet stores. The fish in question live in several springs in southern Mexico that have a high concentration of hydrogen sulfide gas.

Tobler will use another group of genetically similar fish as a control group. The second group lives in an environment where hydrogen sulfide isn’t present, Tobler said. The study will allow Tobler to compare the two groups in terms of behavior, morphology and, most importantly, genetic makeup, to find out how the fish are able to tolerate the toxin.

“The goal is to find the genes that underlie the ability to tolerate the toxic conditions,” Tobler said. “To be frank, there’s not a whole lot of animals that manage to survive in these highly toxic environments.”

Scant research has been done on the fish in the past, Tobler said. Biologists have studied the area around the springs, he said, but that research was mainly limited to what fish species occur in the area.

Likewise, microbiologists have studied how bacteria and other microbes survive in toxic conditions, Tobler said, but the amount of work done by zoologists and plant biologists on environments rich in hydrogen sulfide has been limited.

In fact, some of the only similar research was done by Tobler himself during his postdoctoral fellowship at Texas A&M.

During that project, Tobler measured how much hydrogen sufide was present in the springs and determined it to be a level of concentration that would be lethal to most animals. When it came time to write a grant for the current project, his previous research helped him make the case for the funding, he said, and his research over the next three years will, in many ways, be building on that study.

A greater understanding of hydrogen sulfide and how it affects animals will be vital in the years to come, Tobler said. Hydrogen sulfide is “a huge problem” in industrial processes, he said, and as industry grows worldwide, that problem will only be compounded.

There has also been some research that shows the possibility of using the gas in a hospital setting — for instance, to put patients in a dormant state. If that use ever becomes a viable option, he said, it will be critical to understand how animals’ bodies process the gas.

Up to now, Tobler said, any understanding of the gas and its effects is limited. The sulfur springs in southern Mexico provide a good location for doing the research necessary to increasing that understanding, he said, but so far, that resource has remained more or less untapped.

“In general, we know very little about natural hydrogen sulfide and how it affects organisms,” he said. “The sulfur springs are virtually unstudied.”