The Russian olive trees were planted as windbreaks for their ability to grow in poor soil. The mosquito fish went into the water to eat their namesake biting bugs.
But now the thorny trees are crowding out the native willows, and the aggressive fish are taking over from the least chub, whose Utah ancestry traces back some 18,500 years.
The ecosystem at Mona Springs is being decimated by those and other non-native species, said Utah Valley University student Josh Brook. "Utah has very little wetlands," he said. "Preserving what we have is very important."
The senior is one of a group of conservation biology students, led by associate professor Catherine Stephen, volunteering to help. On a recent trip to the springs, located just south of Mona Reservoir in Juab County, 13 students worked with the Utah Division of Wildlife Resources to remove invasive species with chainsaws, nets and their hands.
The students also have been monitoring native species like the least chub. The minnow is native to the prehistoric Lake Bonneville and used to live in many ponds and streams near Salt Lake City and the Great Salt Lake. But with the introduction of invasive species, such as carp and the mosquito fish, the least chub's population has dwindled to just six locations.
Ironically, the chub eats the larvae the mosquito fish was introduced to eliminate.
"If the ecosystem would have been healthy we would have had no problem," said Nicholas Bunnell, a senior criminal justice major with a minor in biology.
The native willows, meanwhile, were also trampled by grazing cattle. The area around the springs is now protected.
"Without the cattle, they can hold their own," Brook said.
Returning the springs to its natural state could also help boost bird populations. "We do see individuals, no big flocks or anything," said Stephen. "This will change things dramatically."
Other natives, such as the Columbia spotted frog and a mussel called the California floater, are also expected to thrive. Humans stand to benefit from a healthier springs too.
The wetlands filter water for Mona Reservoir, a popular recreation spot, and if a bird population were to take root there, it could be popular for bird watchers and hunters.
"I'm a waterfowl hunter, and I recreate on Mona Reservior," Bunnell said. "The reservoir really benefits from this project."