Cyanobacteria and Cyanotoxins: The Influence of Nitrogen versus Phosphorus

Abstract

The importance of nitrogen (N) versus phosphorus (P) in explaining total cyanobacterial biovolume, the biovolume of specific cyanobacterial taxa, and the incidence of cyanotoxins was determined for 102 north German lakes, using methods to separate the effects of joint variation in N and P concentration from those of differential variation in N versus P. While the positive relationship between total cyanobacteria biovolume and P concentration disappeared at high P concentrations, cyanobacteria biovolume increased continually with N concentration, indicating potential N limitation in highly P enriched lakes. The biovolumes of all cyanobacterial taxa were higher in lakes with above average joint NP concentrations, although the relative biovolumes of some Nostocales were higher in less enriched lakes. Taxa were found to have diverse responses to differential N versus P concentration, and the differences between taxa were not consistent with the hypothesis that potentially N 2 -fixing Nostocales taxa would be favoured in low N relative to P conditions. In particular Aphanizomenon gracile and the subtropical invasive species Cylindrospermopsis raciborskii often reached their highest biovolumes in lakes with high nitrogen relative to phosphorus concentration. Concentrations of all cyanotoxin groups increased with increasing TP and TN, congruent with the biovolumes of their likely producers. Microcystin concentration was strongly correlated with the biovolume of Planktothrix agardhii but concentrations of anatoxin, cylindrospermopsin and paralytic shellfish poison were not strongly related to any individual taxa. Cyanobacteria should not be treated as a single group when considering the potential effects of changes in nutrient loading on phytoplankton community structure and neither should the N 2 -fixing Nostocales. This is of particular importance when considering the occurrence of cyanotoxins, as the two most abundant potentially toxin producing Nostocales in our study were found in lakes with high N relative to P enrichment.

Nutrients drive transcriptional changes that maintain metabolic homeostasis but alter genome architecture in Microcystis

“…For decades, phosphorus (P) loading has been cited as the primary cause of bloom events (Schindler, 1977). This paradigm has begun to shift in recent years, however, to recognize a potential role for nitrogen (N) concentrations and chemical forms in driving bloom formation and biological community structure (Dolman et al, 2012). Although this shift remains hotly debated (Downing et al, 2001;Scott and McCarthy, 2010;Paerl et al, 2011;Paterson et al, 2011), it is clear that Microcystis exhibits a differential response when exposed to various N-containing chemical species (Donald et al, 2011) and concentrations (Vézie et al, 2002), as well as various P concentrations both in the environment (Wilhelm et al, 2003;Davis et al, 2010) and in culture (Shen and Song, 2007;Harke et al, 2012).…”

“…Although this shift remains hotly debated (Downing et al, 2001;Scott and McCarthy, 2010;Paerl et al, 2011;Paterson et al, 2011), it is clear that Microcystis exhibits a differential response when exposed to various N-containing chemical species (Donald et al, 2011) and concentrations (Vézie et al, 2002), as well as various P concentrations both in the environment (Wilhelm et al, 2003;Davis et al, 2010) and in culture (Shen and Song, 2007;Harke et al, 2012). Specifically, urea appears to stimulate rapid biomass accumulation of Microcystis when it enters fresh water as fertilizer runoff (Dolman et al, 2012). Despite decades of research, the cellular mechanisms driving these notably different responses to N-reduction and composition versus P-reduction remain undiscovered.…”

Cyanobacterial dynamics and toxins concentrations in Lake Alto Flumendosa, Sardinia, Italy

“…We tested whether CB abundance could be a good proxy for MC concentration in the lake, as it has been shown by many studies on Planktothrix (Briand et al, 2005;Catherine et al, 2008;Dolman et al, 2012;Salmaso et al, 2014). A prerequisite for this relationship to be significant is the presence of a single dominant species (Salmaso et al, 2014).…”

Using Chemically Treated Organic Recycling Materials to Enhance Freshwater Purification

“…11). In addition, strong reduction (86%) was noted on day 11, when a high level of phosphates was measured (1.24 mg PO 4 3-L -1…”

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The development of civilization and its accompanying anthropopressure have increased the accumulation of biogenic elements in aquatic ecosystems, which has accelerated the eutrophication of water bodies all over the world [1][2][3], and by doing so increased the production of tides of toxic cyanobacteria [4][5]. There is, therefore, a need to integrate ecohydrology with engineering solutions on the catchment scale to slow the rate of eutrophication [6], with the potential to permanently decrease the content of bioavailable phosphorus in water supplies Pol.

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