2016 review

The dual role of nitrogen supply in controlling the growth and toxicity of cyanobacterial blooms

[Review of ]. HARMFUL ALGAE, 54, 87–97.

By: C. Gobler*, J. Burkholder n, T. Davis*, M. Harke *, T. Johengen*, C. Stow *, D. Waal *

co-author countries: Netherlands πŸ‡³πŸ‡± United States of America πŸ‡ΊπŸ‡Έ
author keywords: Nitrogen; Phosphorus; Cyanobacteria; Microcystis; Diazotrophy; Nutrients
MeSH headings : Cyanobacteria / metabolism; Cyanobacteria / physiology; Fresh Water / chemistry; Fresh Water / microbiology; Microcystins / metabolism; Microcystins / toxicity; Nitrogen / metabolism; Phosphorus / metabolism
Source: Web Of Science
Added: August 6, 2018

Historically, phosphorus (P) has been considered the primary limiting nutrient for phytoplankton assemblages in freshwater ecosystems. This review, supported by new findings from Lake Erie, highlights recent molecular, laboratory, and field evidence that the growth and toxicity of some non-diazotrophic blooms of cyanobacteria can be controlled by nitrogen (N). Cyanobacteria such as Microcystis possess physiological adaptations that allow them to dominate low-P surface waters, and in temperate lakes, cyanobacterial densities can be controlled by N availability. Beyond total cyanobacterial biomass, N loading has been shown to selectively promote the abundance of Microcystis and Planktothrix strains capable of synthesizing microcystins over strains that do not possess this ability. Among strains of cyanobacteria capable of synthesizing the N-rich microcystins, cellular toxin quotas have been found to depend upon exogenous N supplies. Herein, multi-year observations from western Lake Erie are presented demonstrating that microcystin concentrations peak in parallel with inorganic N, but not orthophosphate, concentrations and are significantly lower (p<0.01) during years of reduced inorganic nitrogen loading and concentrations. Collectively, this information underscores the importance of N as well as P in controlling toxic cyanobacteria blooms. Furthermore, it supports the premise that management actions to reduce P in the absence of concurrent restrictions on N loading may not effectively control the growth and/or toxicity of non-diazotrophic toxic cyanobacteria such as the cosmopolitan, toxin-producing genus, Microcystis.