Students in Beverly Adams’ ecology class at Payson High School know that a fish’s cheeks will balloon with too much dissolved oxygen in the water.
“We did a whole unit on that,” Adams said about dissolved oxygen. Didn’t know oxygen could dissolve? Think again.
“They die,” said Nick Gonzalez about the fish subjected to overloads of the element. Just as too little oxygen can kill fish, so can too much.
“Remember, their cheeks get all swelled up,” Gonzalez said to classmate Keaton Duran.
“What would make dissolved oxygen go down?” Adams quizzed her students.
Rising temperatures, said Duran after some additional prodding by Adams.
Ecology students and select biology students packed onto a school bus Thursday, traveling to different points along the Verde River to measure pH levels of water, velocity and depth, and to look for organisms. At the year’s end, students will compile and present their findings to the Salt River Project, which provided money for the trip.
Half the students crowded by the river with Adams, measuring pH levels — acid — and determining the chemical content of water by using spectrophotometers. The machine shoots light through vials of water, and students determine chemical composition based on transparency. Chemicals the students have found include phosphate, nitrate and the aforementioned dissolved oxygen.
The broken temperature gauge on the measuring instrument sophomore Taylor Goss was using precluded him from ascertaining the exact temperature. Goss, however, guessed it was 4 degrees Celsius, which he explained equaled roughly 40 degrees Fahrenheit.
Slightly down river, students wearing waders stepped gingerly into the water with measuring sticks and string to determine depth and width. They also sought out signs of life.
Biology teacher Joe Schmidt held up a leaf upon which, under further examination, students could spy a tiny aquatic worm lounging. The worms burrow in the river’s bottom, Schmidt said.
“For as much human use (as the Verde gets), it’s a pretty healthy stream,” he added. By inventorying various invertebrates such as the stonefly larvae that students found, they can determine the water’s health.
Stonefly, for instance, need rather clean water. Chemicals, Schmidt said, offer a snapshot of stream health, while the organisms found offer a longer timeline. The presence of delicate organisms means that high water quality has been relatively consistent over a longer period.
That day, in that spot in East Verde Estates, the water ranked fair. “This is the lowest site down,” Schmidt said. As students measure spots farther upstream, the water becomes cleaner because it’s closer to the spring, he added.
Contingents of varying students take these trips six times each year. Next time, physics and life science kids will try their hands at measuring levels of acidity and finding macro and micro-organisms.
“This is good science — real science,” Schmidt said. “The more kids we have involved, the more they’ll be aware of water quality issues.”
This is the third year students have taken the trips. The first year was a pilot program funded by Arizona Public Service. Salt River Project funded both this year’s and last year’s trips.
“I think this is the most unique trip we have,” Schmidt said.