Article Title

Salinity Thresholds, Lake Size, and History: A Critique of the NAS and CORI Reports on Mono Lake





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These two reports usefully summarize and evaluate large amounts of information. They both suffer from and perpetuate, however, a deficient concep- tual framework for analyzing changes in the Mono Lake ecosystem. Specifically, their assessments of the present and future state of this lake 1) use language implying that salinity-induced changes in the biota will begin to occur only at certain critical salinity thresholds, 2) neglect the significance of lake size as a determinant of bird food supplies, and 3) lack historical perspective in failing to consider what changes in the lake ecosystem may have been caused by historical changes in the salinity and size of the lake. The desirability of developing explicit models for the system is emphasized. Especially needed are models for: 1) the influence of salinity and lake size on the abundance of brine flies and brine shrimp, and 2) the influence of the abundance of these invertebrates on the bird populations that use the lake. To illustrate the heuristic value of such models, Rawson's models relating productivity and standing crop to lake mean depth are applied to Mono Lake. The results suggest some unusual consequnces of the lake's particular mor- phometry, especially for lake level changes between 6370 ft and 6380 ft.