AN ECOLOGICAL STUDY OF MONO LAKE, CALIFORNIA Edited by David W. Winkler for the Mono Basin Research Group Institute of Ecology Publication, No. 12 June, 1977 University of California, Davis Reprinted November, 1979 by the Mono Lake Committee, PO Box 29, Lee Vining, CA 93541 Note for the Electronic Version: August 2006 This electronic Adobe PDF version of the 1976 Ecological Study of Mono Lake (including the 1980 update at the end) was created by the Mono Lake Committee in August 2006 for the 30th anniversary of the study. It was scanned at 400 dpi and error checked using Adobe Capture 2 OCR software with an accuracy preset to 95%. In many (but not all) cases, obvious misspellings and errors were corrected in this electronic version. Many OCR errors that the software did not catch were caught manually, indicating that it is likely there are additional errors that were not caught by the software or the human editor. The main sources of error were: hard to OCR fonts and printing, numbers, equations, symbols, scientific terms, tables, charts, and sheet feeder problems. In July 2006, the Mono Basin Research Group held a 30-year reunion. At a picnic at Mono Lake County Park, a copy of the study from the Mono Lake Research Library was circulated for signatures, resulting in the following page. If you have any questions or comments regarding the electronic version of this document, please contact: Mono Lake Committee, P.O. Box 29, Lee Vining, CA 93541. AN ECOLOGICAL STUDY OF MONO LAKE, CALIFORNIA Edited by David W. Winkler for the Mono Basin Research Group Institute of Ecology Publication No. 12 June, 1977 Institute of Ecology, University of California, Davis, California 95616 FOREWORD : A NOTE ON THE HISTORY OF MONO LAKE David Gaines Give me silence, water, hope Give me struggle, iron, volcanoes Pablo Neruda East of Yosemite National Park lies one of the most beautiful and scientifically in- teresting regions in California. This land of granite escarpments, glacier-scoured can- yons, volcanoes, and lava flows is dominated by the blue expanse of Mono Lake. For at least 700,000 years Mono Lake has lain at the foot of the Sierra Nevada's steep eastern escarpment. During the Pleistocene glaciations, the lake waxed to several times its present size and depth. Perhaps as recently as 13,000 years ago, tongues of ice reached its shores and icebergs drifted on its surface. At times its waters overflowed into Owens Valley and even into Death Valley. Conversely, during interglacial periods, Mono Lake shrank into its tectonically-formed drainage basin and became a lake without an outlet to the sea. A series of wave-cut terraces on the slopes above the lake have left us a record of its expansions and contractions. Despite these fluctuations, Mono Lake never dropped much below its present volume. It survived perhaps a million years of glacial and interglacial climatic cycles to become one of the most ancient inland bodies of water in North America (Lajoie 1968). Now the water demands of a metropolis 300 miles distant threaten the future of Mono Lake. Since 1941, water from four of the five major streams that feed the lake has been diverted into the Los Angeles aqueduct. The consequence is strikingly apparent. Mono's shores are marked by a conspicuous band of white, alkali-encrusted rocks and sand--a bathtub ring left by the shrinking lake. What will happen if these diversions continue? According to the Los Angeles Depart- ment of Water and Power, Mono Lake will eventually stabilize at a lower level (Lane et al. 1974): . assuming a continuation of the dry cycle that began in 1920, the level of the lake would stabilize in about 100 years at a level 50 to 60 feet lower than its present elevation with a surface area of about one-half the present size. A repeat of the wet cycle which occurred prior to 1920 could mean that the lake would stabilize at an elevation only 30 feet lower than its present level. These predictions are controversial. Dennis Williams, hydrologic engineer with the Department of Water and Power, has conceded that they are based on an informal study in which the Department does not have 100 percent confidence. Data on evaporation rates, precipitation, and inflow from underground springs is little more than guesswork (Harding 1964). Even the diversion rate used in obtaining these predictions is equivocal. Was the nearly two-fold increase in diversion which began in 1970 taken into account?' In the opinion of Ken Lajoie, Chairman of the Sierra Club Mono Lake Task Force, the future of the lake is probably much more uncertain than the Los Angeles Department of Water and Power is willing to admit. Unfortunately, unless more thorough studies are undertaken, the truth may not be known until irreversible changes have occurred. During the summers of 1974 and 1975, several undergraduate biology students working at nearby Tioga Pass became interested in Mono Lake and its ecology. Struck by the dearth of descriptive and quantitative data about the region, especially with regard to bird populations, these students applied for and received a grant from the National Science Foundation. The resultant Mono Basin Research Group, twelve undergraduates from Stanford University, the University of California at Davis and at Santa Cruz, and Earlham College, pursued an energetic program of field and laboratory research during the summer of 1976. Their work has produced reliable data and analysis of littoral vegetation, the effects of salinity increase on plankton and brine flies, the density, species composition, and food sources of birds, and other important physical and biotic parameters. This research, pre- sented here with summaries of previous studies, warrants the interest not only of biolo- gists and naturalists, but of all those concerned with Mono Lake's future. This product of the Mono Basin Research Group's efforts does not obviate the need for further study; rather, it makes that need all the more imperative. Three months of field work could uncover only the beginning of an answer to the question of how water diversions are going to affect the lake and its-basin. AN ENDANGERED ECOSYSTEM? Early white travelers were awed by the panorama of peaks and volcanoes which graces Mono's shores. Geologist Israel Russell (1889) described the view as follows: In the middle distance there rests upon the desert plain what appears to be a wide sheet of burnished metal, so brilliant and even is its surface. It is Lake Mono. At times the waters re- flect the mountains beyond with strange distinctness. No prosaic description can portray the grandeur of fifty miles of rugged mountains, rising beyond a placid lake in which each sharply cut peak, each shadowy precipice, and each purple gorge is reflected. Alkali dust may obscure such a view in the future, although the Los Angeles Department of Water and Power has argued that the lake and its basin will continue to provide visi- tors with "an impressive sight" (Lane et al. 1974). The alkaline chemistry of the dust is especially insidious. It may-affect vegetation far from Mono Lake itself, including valuable Jeffrey Pine forests. A hundred miles to the south, the desiccation of Owens Lake, formerly a lake similar to Mono, serves as an example. There air pollution has become so severe that "the dust commonly reduces horizontal visual range to less than one mile some 60 miles from its source" and "number and mass concentrations of the particulates. are a hazard to health" (Reinking et al. 1975). The future of the many living organisms which depend on Mono Lake for sustenance is of equal concern. The lake which Mark Twain called "solemn, silent and sailless" is in reality neither dead nor silent (Clemens 1872). Although ignorant of the enormous fecun- dity of Mono Lake's phytoplankton, early visitors remarked on its large flocks of birds. In 1865, J. R. Browne wrote the earliest published reference to the California Gull rook- eries on Mono's islands: Immense swarms of gulls visit these islands during the spring of the year and deposit their eggs on every available spot. Myriads upon myriads of them hover over the rocks from morning till night, deaf- ening the ear with their wild screams, and the water is literally covered with them for a circle of many miles. The threat to the Negit Island California Gull rookery, the largest in the state, has already been recorded (Stallcup and Greenberg 1974): A breeding colony of 20-30,000 California Gulls is located on 160 acre Negit Island. the water level (of Mono Lake) is decreasing at an alarming rate. it is estimated that by 1976 a land bridge will have emerged between the shore and Negit Island allowing pre- dators to commute and insuring. total destruction of the population.2 In addition to gulls, hundreds of thousands of grebes and phalaropes visit Mono Lake on their migratory journeys. The fate of Mono Lake's bird populations is closely linked to that of the brine shrimp and brine flies on which they feed. These, in turn, are dependent on the half-a-dozen photosynthesizing phytoplankton species which comprise the base of the food chain (Mason 1965). Changes in Mono Lake chemistry will be of critical importance here. If, as predicted, Mono Lake drops to an elevation of 6,320 feet, it will retain only one-fourth its present volume. Already, evaporation has concentrated its waters to twice the salinity and ten times the alkalinity of seawater (Mason 1965). If diversions continue, carbonates and other solutes could increase to about four times ii their present densities.