THE HOLOCENE PALEOLIMNOLOGY OF FAVRE LAKE, RUBY MOUNTAINS, NEVADA, USA
Favre Lake is a small (7.7 ha), relatively shallow (12 m deep) tarn at an elevation of 2,902 m. Much of the watershed surrounding Favre Lake is covered by a veneer of glacial till, which may obscure evidence of water flowing from the adjacent lakes. The abundance of glacial till in the basin indicates that Favre Lake is only partially underlain by crystalline bedrock.
Diatom assemblages were identified and biogenic silica abundance measurements were taken from a 4.2-m-long sediment core collected from the deepest part of the lake. Small fragilarioid taxa (Pseudostaurosira, Staurosira, and Staurosirella) comprise as much as 80% of the assemblage. The remainder of the assemblage is dominated by benthic taxa. Planktonic species are account for about 10% of the assemblage. Biogenic silica values vary between 20 and 30 wt %. These proxies suggest that the lake was small between 7,700 and 5,500 cal yr BP; for most of the remainder of the record, the lake covered a shallow (~1 m deep) shelf, resulting in the dominance of small fragilarioid diatoms. Planktonic species increase in abundance in the last 200 years, indicating the establishment of modern conditions.
Increased knowledge of the behavior of high elevation aquatic ecosystems will improve our ability to develop and evaluate adaptive management strategies appropriate to freshwater ecosystem potential responses to projected climate change.