Dianna Bautista
About the author

Dianna Bautista is a freelance science writer with a background in biochemistry and science communication. She enjoys breaking down and writing about environmental research. She's written for Asian Scientist Magazine, California Magazine, the Stowers Institute for Medical Research, and more. When she isn't writing, she can be found swimming in any available open pool.

Articles by Dianna Bautista


Researchers are applying a novel genetic technique as part of the development of an annual estimate for the number of juvenile spring-run Chinook salmon entering the Delta.

The technique, spearheaded by geneticist Melinda Baerwald from the California Department of Water Resources, allows researchers to accurately distinguish young spring-run salmon from other runs by targeting DNA sequences specific to these fish.   In a paper published in San Francisco Estuary and Watershed Science, lead authors Baerwald and Peter A. Nelson explain some of the challenges of developing this estimate, called the spring-run juvenile production estimate. A key hurdle is differentiating spring-run fish from salmon that migrate during other seasons. Unlike juvenile salmon from the winter run, spring-run juveniles are hard to identify using the conventional length-at-date approach, which determines age and spawning migration season based on size.   “There’s nothing visually about a spring-run salmon that distinguishes it...
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chart by Hutton

An examination of 50 years of records reveals an apparent seasonal bias in estimates of freshwater flow from the Delta to the San Francisco Estuary.

The seasonal bias suggests flows were overestimated during the summer months and underestimated during the winter. Estimates of Delta outflow use a measurement called net Delta outflow index (NDOI), which is determined by taking the amount of Delta inflow, from sources such as the Calaveras, Sacramento, and San Joaquin rivers, and subtracting Delta exports, a direct measurement, and net Delta channel depletions. A team led by TetraTech’s Paul Hutton compared NDOI estimates against measured Delta outflow at four points, as well as against the Estuary’s historical salinity record. The study, which appears in the December 2021 issue of San Francisco Estuary and Watershed Science, focused on net Delta channel depletions, which are determined indirectly and involve considerations such as land...
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