Diatom Assemblages and Ionic Characterization of Lakes of the Northern Great Plains, North America: A Tool for Reconstructing Past Salinity and Climate Fluctuations

Abstract

The distribution of diatoms with respect to salinity and ionic gradients was studied in lakes of the northern Great Plains of North America. The lakes range from freshwater to hypersaline (0.65–270 g∙L−1) and include a variety of brine types, although the majority are dominated by sulfate salts. Canonical correspondence analysis of diatoms in the surface sediments of 66 lakes and associated water chemistry data indicates that diatom distributions are highly correlated with salinity. The ordination also suggests that brine type forms a significant environmental gradient and separates taxa characteristic of bicarbonate/carbonate lakes from those of sulfate-dominated systems. The salinityoptima and tolerances of diatom species are calculated by weighted averaging regression, and these data provide a tool for the reconstruction of past salinity and the inferance of climatic change in arid and semiarid regions.

Century scale paleoclimatic reconstruction from Moon Lake, a closed‐basin lake in the northern Great Plains

“…Evidence for a meromictic state is suggested by the dominance of Cyclotella choctawhatcheeana (Fig. 7A), which is most abundant in modern-day surface samples from meromictic lakes (Fritz et al 1993). Similarly, Medicine Lake, a meromictic lake, became dominated by C. choctawhatcheeana with the expansion of prairie conditions (Radle et al 1989).…”

“…Similarly, Medicine Lake, a meromictic lake, became dominated by C. choctawhatcheeana with the expansion of prairie conditions (Radle et al 1989). C. choctawhatcheeana (Prasad et al 1990) is currently recognized as the correct epithet for the taxon referred to as Cyclotella caspia by Radle et al (1989), Fritz (1990), and Fritz et al (1991, 1993 (Carvalho et al 1995). During the mid-Holocene, a short interval of rapid sediment deposition (N 6600-6300 B.P.)…”

“…Rhoicosphenia curvata, Mastogloia smithii, and Mastogloia elliptica). Taxonomic names and authorities follow those of Fritz et al (1993). Salinity reconstructions were calculated by a salinityweighted-averaging regression and calibration model with the program WACALIB v. 3.3 (Line et al 1994) and based on a transfer function developed by Fritz et al (199 1, 1993).…”

“…Because diatoms are sensitive to lake chemistry, fossil diatom assemblages preserved in lake sediments record past hydrochemical conditions. In this study, we use quantitative salinity-inference techniques based on modern diatom distribution in relation to waterchemistry gradients in the northern Great Plains (Fritz 1990;Fritz et al 199 1, 1993) to reconstruct changes in effective moisture (precipitation minus evapotranspiration, P -ET) for a climatically sensitive site, Moon Lake, North Dakota. Century-scale climatic fluctuations at this site are then compared with other paleoclimatic records from the northern Great Plains to assess broad-scale regional trends vs. local-scale variability.…”

Limnological and Climatic Environments at Upper Klamath Lake, Oregon during the past 45 000 years

“…The occurrence of Cyclotella michiganiana, a planktic diatom whose salinity optimum is between 1 and 2 g/l (Fritz et al 1993) indicates that by 8 ka openwater habitats of Upper Klamath Lake had also become slightly more saline and alkaline. The partial replacement of Staurosira construens by Pseudostaurosira brevistriata at that time and until 5 ka also suggests that the water of Upper Klamath Lake became somewhat more concentrated because P. brevistriata has a higher salinity optimum than S. construens (Cumming and Smol 1993).…”