The Fishes of Lake Bonneville: Implications for Drainage History, Biogeography, and Lake Levels
Abstract
This chapter summarizes the paleontological and fish DNA evidence for the fishes that occupied the late Quaternary Bonneville basin and key biogeographic and hydrographic insights that emerge from analyses of those data. Fossils and mtDNA from modern fishes suggest nearly the entire assemblage of 21 species occurred in the region prior to the rise of Lake Bonneville. Ten sites have produced fish materials (N > 16,100 specimens) from the lake. The fauna was similar to that in modern Bear Lake, Utah-Idaho, and had two large salmonine top carnivores, three endemic whitefish zooplanktivores, three bottom or rocky shore dwelling sculpins, several minnows, a large lake sucker, a river sucker, and two mountain suckers. The collection from Homestead Cave, Utah, is the largest, and the richest late Quaternary fish assemblage from the basin. Fish bones from Stratum I of the cave provided Sr-87/Sr-86 values suggesting that they were derived from a low-elevation lake and change in fish size and taxonomic abundance suggest the fauna resulted from a series of die-offs resulting from increases in temperature and salinity. Radiocarbon dating suggests this occurred rapidly between 13.1 and 11.8 cal ka BP at the end of the regressive phase of Lake Bonneville. A recolonization of nearly the entire Lake Bonneville fish fauna occurred between 12.3 and 9.5 cal ka BP during the Gilbert episode, although the fauna is skewed to higher abundances of salinity-and temperature-tolerant taxa. No post-Gilbert early Holocene lake transgressions are suggested but peaks in Gila atraria frequencies in the upper strata may indicate Great Salt Lake reached highstands at similar to 3.6 and similar to 1.0 cal ka BP.
