Nitrogen study at Lake Tahoe shines new light on global change | TahoeDailyTribune.com

Nitrogen study at Lake Tahoe shines new light on global change

Tribune staff report

Ever wonder what makes Lake Tahoe’s waters so clear? One of several factors is the amount of nitrogen coursing through the lake.

Nitrogen can affect the lake’s ecosystem, including its food web and the composition of microscopic single-cell organisms called microbes, which support nutrition to other organisms in the water.

Recently, a study tracked nitrogen in Lake Tahoe to get a better idea of how the nutrient is cycled through the ecosystem. And what researchers found provides new information on how climate change may affect the lake, according to a news release.

“It’s important to study the life cycle of nitrogen in the ecosystem since increasing atmospheric nitrogen deposition can alter the food web in the lake,” said the study’s lead author, Stuart Goldberg, in a statement. “Just like a home garden, the health of lake ecosystems relies on the balance of nutrients like nitrogen and phosphorus.”

Goldberg is also a former post-doctoral researcher at the Scripps Institution of Oceanography, which led the study.

The study was published in the Feb. 23 issue of Nature Communications and looked at how both natural and man-made sources of nitrogen are recycled through Lake Tahoe’s ecosystem.

Among other things, researchers discovered “that some nitrogen was preserved in the proteins and unavailable for biological consumption for 100 to 200 years,” according to the Scripps news release.

Lihini Aluwihare, associate professor of geosciences at Scripps Institution of Oceanography in San Diego, said it is unusual for organic nitrogen to be sitting around for that long.

“This changes our view of how quickly nutrients are recycled in high-elevation lake ecosystems,” Aluwihare, a co-author of the study, said in a statement.

Tests conducted by members of Scripps Oceanography and the UC Davis Tahoe Environmental Research Center found that something is preventing the “efficient recycling of nitrogen in these ecosystems,” according to Scripps. One reason for this could be an unbalanced amount of phosphorous and nitrogen in the ecosystem.

The institution notes that the nutrient balance has begun to be altered through regional warming, changes in precipitation patterns and increased atmospheric nitrogen deposition.

“This investigation has found that dissolved organic matter can store nitrogen in lake systems,” stated Lina Patino, program director for the Earth Sciences Postdoctoral Fellowship Program, which funded the research. “This is important because to understand the environmental health of lakes, we need to know the sources of the nutrients and where they are stored.”

Other co-authors of the study include Brant Allen and Geoffrey Schladow of TERC; Andre Simpson, Hussain Masoom and Ronald Soong of the University of Toronto; and Heather Graven of Imperial College in London.