Algal growth potential and nutrient limitation in the Las Vegas Bay, Lake Mead, Nevada

Algal bioassays were conducted to determine algal growth potential (AGP) and nutrient limitation of the Las Vegas (LV) Bay of Lake Mead using the standard test organism Selenastrum capricornutum and the Lake phytoplankton. Results for the current nutrient levels in the LV Bay revealed that the AGP of the LV Bay waters, measured by the maximum specific growth rates is limited by phosphorus (P). Both the growth rates and the biomass content indicated the LV Bay is P-limited. Bioassay results, using higher nitrogen (N) and phosphorus levels, showed that increasing the N and P of the Bay concentrations to levels higher than the current values, significantly increased the algal growth rates and the biomass content of the Bay. Correlation of algal growth rates and biomass with P and N levels for all control waters, showed a very strong relationship between algal growth rates and the dissolved ortho-phosphate concentrations for the Lake phytoplankton. This relationship is weaker for S. capricornutum demonstrating the sensitivity of the Lake phytoplankton to increased P levels.