SJ & Jessie E. Quinney College of Natural Resources, Utah State University
The Great Salt Lake, lacking fresh water, is becoming saltier. The lake is losing sources of fresh water to agriculture, urban growth and drought, and the drawdown is causing salt concentrations to increase even beyond the tolerance limits of brine shrimp and brine flies, according to Wayne Wurtsbaugh of Watershed Sciences at Queen’s College of Natural Resources. .
Deciphering the ecological and economic implications of this change is complex and unprecedented, and experts are closely watching another stressed salt lake to learn what to expect next – Lake Urmia in Iran. This “sister lake” offers clear and troubling parallels to the fate of the Great Salt Lake, according to a new study by Wurtzbaugh and Somae Sima of Tarbiyat-Modares University in Tehran.
The history of both lakes followed similar trajectories, albeit at different rates. As less fresh water moves through the connected rivers and streams into these lakes, natural salts become more and more concentrated in the water. Native brine flies and brine shrimp tolerate salt, but when salt levels reach certain extreme concentrations – sometimes reaching saturation – even animals and plants specially adapted to salty environments can struggle. It also means millions migratory birds that depend on these food sources will also struggle, starve, or leave.
It has been expanding for decades urban population in northern Utah demanded more fresh water for crops, lawns and faucets, gradually increasing the strain on the ecosystem. Now, a 20-year drought is pushing salinity levels to unbearable levels, Wurtbaugh said.
On the Great Salt Lake, a dam divides the lake in half. In the absence of fresh water inputs, the northern arm of the lake (Gunnison Bay) became the most saline with a saturation level. The transfer of salt to the northern arm allowed the southern arm (Gilbert’s Bay) to remain in a concentration range that allows shrimp and flies to tolerate salinity. But salinity in the south is also rising to stress levels even for these hardy species.
The Great Salt Lake and Lake Urmia in Iran were once remarkably similar in size, depth, salinity, and geographic location. High performance the growth of cities demand for irrigated agriculture and human use is also being pushed, putting extreme strain on the ecosystem. Compared to the Great Salt Lake, the fate of Lake Urmia is spinning forward.
In just 20 years, the leak has caused Urmia’s salinity to jump from 190 grams of salt per liter of water to more than 350 grams, Seema said. (For comparison, ocean water has a salinity of about 35 grams per liter.) The decline of the Lake Urmia ecosystem was rapid and easy to recognize. He lost almost all of his brine shrimp. How long brine shrimp can survive in the increasingly salty water of the Great Salt Lake is a question researchers want to understand, especially for the South Arm, where salt concentrations high but still supporting some shrimp.
Gilbert Inlet, in the northern arm of the Great Salt Lake, reached a staggering 330 grams per liter (27 percent salt) and has almost no brine shrimp, halting the $70 million brine shrimp harvest there, Wurtsbaugh said. Now, the shrimp harvest in the southern arm is also threatened by rising water salinity. Brine shrimp prefer a comfortable salt level of 75-160 grams per liter. Larvae of brine flies can withstand higher concentrations of salt solution, but even this extremely hardy species begins to feel the pinch when things are this excessive.
“Brine fly larvae become smaller at such high salt levels, indicating environmental stress,” Wurtsbaugh said. “The combined collapse of these two organisms could have catastrophic ecological consequences for migratory bird populations and the lake’s economy.”
Managers still have the ability to regulate the flow of salt from the north to south arm of the lake with an underwater berm at the levee break. This flow is used to manage the competing demands of the lake’s mining companies and the brine shrimp industry. But if water development and climate change cause further water table losses, even that option will become limited, Wurtzbaugh said.
Lake Urmia has already lost much of its ecological and cultural function, but the Great Salt Lake has yet to cross that chasm, the authors say. The ongoing crisis in the Great Salt Lake and Lake Urmia is not unique — other salt lakes around the world are facing a similar crisis and are drying up completely or losing water rapidly, Wurtsbaugh said. But communities are noticing, which gives him hope. Making any progress will require significant sacrifices from water users to make the lakes sustainable, Wurtsbaugh said.
The study is published in the journal water.
Wayne A. Wurtsbaugh et al, Contrasting Management and Fates of Two Sister Lakes: Great Salt Lake (USA) and Lake Urmia (Iran), water (2022). DOI: 10.3390/w14193005
Courtesy of the University of Utah SJ & Jessie E. Quinney College of Natural Resources
Citation: Great Salt Lake on track to become super-salinity like Iranian lake, new research shows (2022, October 4) Retrieved October 4, 2022, from https://phys.org/news/2022-10-great-salt-lake -path -hyper-salinity.html
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