A diatom-inferred water-depth transfer function from a single lake in the northern California Coast Range

Abstract

This study examines the relationship between water depth and diatom assemblages from lake-sediment-surface samples at Kelly Lake, California. A total of 40 surface-sediment samples (integrated upper 5 cm) were taken at various depths within the small (~ 3.74 ha) 5.7 m-deep lake. Secchi depths, water temperature, pH, salinity, conductivity, and total dissolved solids were also measured. Some diatom species showed distinct association with depth (e.g., Fragilaria crotonensis, Nitzschia semirobusta). The relationship between the complete diatom assemblages and water depth was analyzed and assessed by depth-cluster analysis, a one-way analysis of similarity, principal components analysis and canonical correspondence analysis. Statistically significant differences were found between the assemblages associated with shallow depth (0–1.25 m), mid-depth (1.25–3.75 m), and deep-water (3.75–5.2 m) locations. The relationship between diatom assemblages and lake depth allowed two transfer models to be developed using the Modern Analogue Technique and Weighted Averaging Partial Least Squares. These models were compared and assessed by residual scatter plots. The results indicate that diatom-inferred transfer models based on surface-sediment samples from a single, relatively small and shallow lake can be a useful tool for studying past hydroclimatic variability (e.g., lake depth) from similar lakes in California and other regions where the large number of lakes required for traditional transfer-function development may not exist.