Nutrients and water temperature are significant predictors of cyanobacterial biomass in a 1147 lakes data set

Abstract

Using a , 1000 lake data set that spans the entire continental United States, we applied empirical modeling approaches to quantify the relative strength of nutrients and water temperature as predictors of cyanobacterial biomass (CBB). Given that cyanobacteria possess numerous traits providing competitive advantage under warmer conditions, we hypothesized that water temperature, in addition to nutrients, is a significant predictor of CBB. Total nitrogen (TN), water temperature, and total phosphorus were all significant predictors of CBB, with TN explaining the most variance. Using multiple linear regression analysis, we found that TN and water temperature provided the best model and explained 25% of the variance in CBB. However, when the data set was divided according to basin type, these same variables explained a higher amount of the variation in deep natural lakes (33%, n 5 253), whereas the least amount of variation was explained by these variables in shallow reservoirs (12%, n 5 307). Competing path models on the full data set using the best variables selected by multiple linear regression show that nitrogen and temperature are indirectly linked to cyanobacteria by association with total algal biomass, which likely reflects changes in light climate and other secondary factors. Our models also indicated that temperature was linked to cyanobacteria by a direct pathway. Under a scenario of atmospheric CO 2 doubling from 1990 levels (resulting in an estimated 3.3uC increase of the maximum lake surface water), we predict on average a doubling of CBB.

Cyanotoxins in inland lakes of the United States: Occurrence and potential recreational health risks in the EPA National Lakes Assessment 2007

“…The genera level was the lowest taxonomic level used in this analysis due to incomplete or inconsistent taxonomy at species level. Contrary to previous reports (Beaulieu et al, 2013), picoplankton were identified in some, but not all, samples. Since there was no means to correct for partial identification of picoplankton in the dataset, picoplankton have significance in the context of microcystin production, and dropping picoplankton from the analysis would decrease the accuracy and precision of the enumeration data; data were evaluated with and without picoplankton.…”

“…Cyanobacteria were identified and enumerated as described in Beaulieu et al (2013). Briefly, preserved samples were counted until 400 natural units were reached.…”

Blooming algae: a Canadian perspective on the rise of toxic cyanobacteria

“…The evidence for the importance of macronutrients in controlling algal biomass and cyanobacterial dominance (or percentage of the assemblage) is overwhelming and stems from early empirical studies (e.g., Trimbee and Prepas 1987;Watson et al 1997), more recent crosssystem modelling of large datasets (Downing et al 2001;Kosten et al 2012;Dolman et al 2012;Beaulieu et al 2013), and the remarkable experiments at the ecosystem scale (Schindler 1977). These studies led to changes in legislation banning P in detergents and regulating loads from point-sources.…”

“…In fact, the only inland waters where cyanobacteria are completely absent from the plankton seem to be acidic (approximately less than pH 5.5; Brock 1973). Total phosphorus (TP) and total nitrogen (TN) are strong predictors of mean cyanobacterial biomass (with snapshot samplings) over large concentration gradients (Downing et al 2001;Beaulieu et al 2013), including Canadian lakes where the nutrient-cyanobacterial models do not differ substantially across regions (Beaulieu et al 2014). These specific factors are not necessarily operative at the within-lake scale (either seasonal or interannual; Tillmanns and Pick 2011).…”

Tracking past changes in lake-water phosphorus with a 251-lake calibration dataset in British Columbia: tool development and application in a multiproxy assessment of eutrophication and recovery in Osoyoos Lake, a transboundary lake in Western North America

“…This typically includes increases in algal biomass, including cyanobacteria blooms which are recognized as a threat to water quality worldwide (O'Neil et al, 2012). Similar to overall algal production, the factors most strongly related to increases in cyanobacteria are nutrients and temperature (Jöhnk et al, 2008;Kosten et al, 2012;Taranu et al, 2012;Beaulieu et al, 2013), as well as lake depth (Taranu et al, 2015).…”