The Effects of Phosphorus Enrichment on the Dominant Phytoplankton Communities of Chaney Lake

• Main Author: Tehrani, Kathy
• Format: Others
• Published: TopSCHOLAR® 1999
• Subjects: Biology; Hydrology
• Online Access: http://digitalcommons.wku.edu/theses/761; http://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=1764&context=theses

Chaney Lake is a temporary karst wetland located in southern Warren County, Kentucky. Because of an impermeable chert layer between the surface and the porous limestone, Chaney Lake fills with water over the winter and spring and then gradually drains over the summer. Three experiments were conducted over the course of the 1998 flooding season to assess the effects of phosphorus addition on the phytoplankton community in Chaney Lake. Ten plastic-sided mesocosms were constructed and placed in the marsh area of the wetland at three different periods: early spring, early summer, and late summer. Phosphorus in the form of K2HPO4 was added by volume to five of the enclosures, with five remaining as controls. The water chemistry parameters measured included soluble reactive phosphate, nitrates, ammonia, and ammonium. Physical parameters such as depth, temperature, dissolved oxygen, dissolved oxygen %, specific conductivity, pH, and turbidity were measured. Chlorophyll a and phytoplankton community structure were also assessed for all three of the experiments. The various parameters were analyzed with Discriminate Function Analysis, ANOVAs, and Pearson Correlations to determine whether there were significant differences between the treated and control enclosures. The results indicate significant differences (P<0.05) between the treated and control enclosures with respect to nitrates, turbidity, and ammonia. There were no significant differences in SRP, chlorophyll a, DO, DO%, SPC, pH, temperature, depth, and phytoplankton composition. It was concluded that phytoplankton in Chaney Lake may not be limited by phosphorus. However, phosphorus may limit bacterioplankton, periphyton, or both. The high nutrient concentrations with low elemental ratios indicate that bacterioplankton may be more efficient in phosphorus utilization and possibly play an important role in nutrient availability for phytoplankton in the marsh area of Chaney Lake.