Baylor Study: Nitrogen Fixation Not Uniform in Texas Lakes

A study by Baylor University biologists found that nitrogen fixation does not happen uniformly on the surface of lakes. In fact, the study found that three specific conditions need to be in place for nitrogen fixation to succeed:

  • Water temperature needs to be above 72 degrees.
  • The ratio of nitrogen to phosphorus needs to be low.
  • The amount of available nitrogen in the water needs to low.

The results appeared in the journal Lake and Reservoir Management

“This study helps us understand when and how nitrogen fixation happens and gives a complete data set that lets us evaluate all of these factors at the same time so we can understand their relative importance,” said Robert Doyle, Ph.D., professor and chair of the department of biology at Baylor, who also is the director of Baylor’s Center for Reservoir and Aquatic Systems Research. “This study shows that for a hot spot of nitrogen fixation to happen, these three environmental conditions need to be in place.”

. Used by bacteria, algae and other organisms, nitrogen fixation is the natural process by which nitrogen in the atmosphere is converted into organic nitrogen. According to the scientific literature, the process is essential for life because nitrogen fixation is required to biosynthesize the basic building blocks of life.

The study looked at five different spots in a Texas reservoir. The researchers then tested the water temperature, pH level, nutrient content and dissolved oxygen content and compared them to nitrogen fixation rates. The results show that nitrogen fixation rates were highest during the months of June through October when the water temperature was above 72 degrees. Likewise, nitrogen fixation rates were low at the deeper test-spots around the lake which had less light.

The results also show that the amount of nitrogen in the water needs to be low and the ratio to nitrogen to phosphorus needs to be below 15 to 1. The amount of available nitrogen in the atmosphere also needs to be low, relative to other nutrients in the water.

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