A Paleolimnological Assessment of Possum Kingdom Lake
Reservoirs are typically considered too young and dynamic to validate paleolimnological analysis (Filstrup et al. 2010). Using biological and mineralogical proxies, three shifts were identified in the history of Possum Kingdom Lake, successfully demonstrating the application of paleolimnology in reservoirs. The trends documented may provide insight into the factors driving the P. parvum blooms that have been responsible for extensive economic losses (Southard, Fries & Barkoh, 2010).
Fig. 1 (Top)This figure displays the relative abundance of diatom valves to the dry weight of the sediment they were found in. Diatoms are not present in countable abundances in Zone 1 (bottom of core to 33 cm) and become much more abundant at 17cm. There is also an apparent decrease in the relative abundance of diatoms in the last few years. Fig. 2 (Bottom) This graph depicts the Calcium to Titanium ratio which can be interpreted as an indication of primary productivity (Krause & Whitlock 2013). Titanium is a general indicator of inorganic minerals eroding into the watershed. An increase in calcium that does not correspond with an increase in titanium indicates that the calcite is being precipitated from the water column due to elevated pH caused by algal growth. This data suggests that diatoms are not present in the bottom of the core due to low productivity and not poor preservation.
