Clam fossils in America's Colorado River delta are telling the tale of an endangered carbon cycle and devastation that befell on the once prosperous, massive green estuary with grasslands and cottonwood.

The dead land's plight was well revealed in a research conducted by scientists at Cornell University, in association with the University of Arizona and Paleontological Research Institution.

The study, "Fossil Clam Shells Reveal Unintended Carbon Cycling Consequences of Colorado River Management," was published in the journal Royal Society Open Science on Sept. 28.

Severe Damage To Carbon Cycling

"We've done a lot in the United States to alter water systems, to dam them. The river irrigates our crops and makes energy. What we really don't understand is how our poor water management is affecting other natural systems - in this case, carbon cycling," said Cornell's Jansen Smith, the lead author of the study and a doctoral candidate in earth and atmospheric sciences.

The research findings summed up the consequences flowing from short-sighted water management policies to long-term consequences.

Noting that the river's ecosystem, shrinking of deltas and the way people dependent on the deltas are hit, the study portrays the biogeochemical consequence of flawed water management in the Colorado River basin.

The study highlights the damage of altered downstream estuarine ecosystem on the population of mollusks there.

The Cornell study analyzed the washed-up clamshells that were hundreds of years old to calculate the annual carbon cycle of the delta.

"We've supplanted a small, natural carbon emitter — the clam — with something far more detrimental to the atmosphere," Smith noted.

The study compared two carbon emission scenarios: emissions from the clams, which would have been the equivalent of emissions from 15,000 cars annually to that of the currently diverted water use whereby many cities are fed at a higher carbon cost and allowing for alarming carbon emissions.

Clams, Mulinia coloradoensis, made a big contribution in estuarine carbon cycling. But their population fell drastically in the Colorado delta from the pre-dam era's 50-125 to just three individuals m−2 today.

The paradox is that reduced carbon emissions at the delta from diverted water flow to Southwestern cities escalated carbon emissions multiple times.

Reflecting on the debilitating effect of the 15 odd dams on the main river and hundreds of small dams on its tributaries, Smith noted that the 1,400-mile-long Colorado river now empties into Mexico's Gulf of California as a mere trickle.

Among the end users of Colorado River include the coal-fired Navajo Generating Station in Arizona, which is a huge carbon dioxide emitter. While Las Vegas splurges on Colorado water for fountains, Arizona uses it for watering golf courses.

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