Trophic conditions and nutrient limitations in the headwaters of Beaver Lake, Arkansas, during a dry hydrologic year, 2005--2006

Algal nutrient limitation and trophic state were evaluated in Beaver Lake, AR from 2005 to 2006. Longitudinal Nitrogen and Phosphorus concentration gradients were observed, and the greatest concentrations were in the riverine zone. Vertical patterns were observed, were SRP showed greater concentrations in the hypolimnion. Chlorophyll-alpha concentrations showed a positive and significant linear relationship with TP and TN. The comparison of historic water quality data showed that in Beaver Lake Chl-alpha and TP concentrations have increased in the past 25 years and the trophic status of the reservoir was eutrophic for the riverine and transitional zone. The increase in Ch-alpha and TP may be attributed to a very dry season and low water levels in the reservoir. Nutrient enrichment bioassays suggest that Beaver Lake nutrient limitations shift from either N or P limitations to co-limitation.