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The role of nitrogen fixation in cyanobacterial bloom toxicity in a temperate, eutrophic lake.
PLoS One. 2013; 8(2):e56103.Plos

Abstract

Toxic cyanobacterial blooms threaten freshwaters worldwide but have proven difficult to predict because the mechanisms of bloom formation and toxin production are unknown, especially on weekly time scales. Water quality management continues to focus on aggregated metrics, such as chlorophyll and total nutrients, which may not be sufficient to explain complex community changes and functions such as toxin production. For example, nitrogen (N) speciation and cycling play an important role, on daily time scales, in shaping cyanobacterial communities because declining N has been shown to select for N fixers. In addition, subsequent N pulses from N(2) fixation may stimulate and sustain toxic cyanobacterial growth. Herein, we describe how rapid early summer declines in N followed by bursts of N fixation have shaped cyanobacterial communities in a eutrophic lake (Lake Mendota, Wisconsin, USA), possibly driving toxic Microcystis blooms throughout the growing season. On weekly time scales in 2010 and 2011, we monitored the cyanobacterial community in a eutrophic lake using the phycocyanin intergenic spacer (PC-IGS) region to determine population dynamics. In parallel, we measured microcystin concentrations, N(2) fixation rates, and potential environmental drivers that contribute to structuring the community. In both years, cyanobacterial community change was strongly correlated with dissolved inorganic nitrogen (DIN) concentrations, and Aphanizomenon and Microcystis alternated dominance throughout the pre-toxic, toxic, and post-toxic phases of the lake. Microcystin concentrations increased a few days after the first significant N(2) fixation rates were observed. Then, following large early summer N(2) fixation events, Microcystis increased and became most abundant. Maximum microcystin concentrations coincided with Microcystis dominance. In both years, DIN concentrations dropped again in late summer, and N(2) fixation rates and Aphanizomenon abundance increased before the lake mixed in the fall. Estimated N inputs from N(2) fixation were large enough to supplement, or even support, the toxic Microcystis blooms.

Authors+Show Affiliations

Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America. lbeversdorf@wisc.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

23405255

Citation

Beversdorf, Lucas J., et al. "The Role of Nitrogen Fixation in Cyanobacterial Bloom Toxicity in a Temperate, Eutrophic Lake." PloS One, vol. 8, no. 2, 2013, pp. e56103.
Beversdorf LJ, Miller TR, McMahon KD. The role of nitrogen fixation in cyanobacterial bloom toxicity in a temperate, eutrophic lake. PLoS One. 2013;8(2):e56103.
Beversdorf, L. J., Miller, T. R., & McMahon, K. D. (2013). The role of nitrogen fixation in cyanobacterial bloom toxicity in a temperate, eutrophic lake. PloS One, 8(2), e56103. https://doi.org/10.1371/journal.pone.0056103
Beversdorf LJ, Miller TR, McMahon KD. The Role of Nitrogen Fixation in Cyanobacterial Bloom Toxicity in a Temperate, Eutrophic Lake. PLoS One. 2013;8(2):e56103. PubMed PMID: 23405255.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The role of nitrogen fixation in cyanobacterial bloom toxicity in a temperate, eutrophic lake. AU - Beversdorf,Lucas J, AU - Miller,Todd R, AU - McMahon,Katherine D, Y1 - 2013/02/06/ PY - 2012/09/05/received PY - 2013/01/09/accepted PY - 2013/2/14/entrez PY - 2013/2/14/pubmed PY - 2013/8/21/medline SP - e56103 EP - e56103 JF - PloS one JO - PLoS One VL - 8 IS - 2 N2 - Toxic cyanobacterial blooms threaten freshwaters worldwide but have proven difficult to predict because the mechanisms of bloom formation and toxin production are unknown, especially on weekly time scales. Water quality management continues to focus on aggregated metrics, such as chlorophyll and total nutrients, which may not be sufficient to explain complex community changes and functions such as toxin production. For example, nitrogen (N) speciation and cycling play an important role, on daily time scales, in shaping cyanobacterial communities because declining N has been shown to select for N fixers. In addition, subsequent N pulses from N(2) fixation may stimulate and sustain toxic cyanobacterial growth. Herein, we describe how rapid early summer declines in N followed by bursts of N fixation have shaped cyanobacterial communities in a eutrophic lake (Lake Mendota, Wisconsin, USA), possibly driving toxic Microcystis blooms throughout the growing season. On weekly time scales in 2010 and 2011, we monitored the cyanobacterial community in a eutrophic lake using the phycocyanin intergenic spacer (PC-IGS) region to determine population dynamics. In parallel, we measured microcystin concentrations, N(2) fixation rates, and potential environmental drivers that contribute to structuring the community. In both years, cyanobacterial community change was strongly correlated with dissolved inorganic nitrogen (DIN) concentrations, and Aphanizomenon and Microcystis alternated dominance throughout the pre-toxic, toxic, and post-toxic phases of the lake. Microcystin concentrations increased a few days after the first significant N(2) fixation rates were observed. Then, following large early summer N(2) fixation events, Microcystis increased and became most abundant. Maximum microcystin concentrations coincided with Microcystis dominance. In both years, DIN concentrations dropped again in late summer, and N(2) fixation rates and Aphanizomenon abundance increased before the lake mixed in the fall. Estimated N inputs from N(2) fixation were large enough to supplement, or even support, the toxic Microcystis blooms. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/23405255/The_role_of_nitrogen_fixation_in_cyanobacterial_bloom_toxicity_in_a_temperate_eutrophic_lake_ L2 - https://dx.plos.org/10.1371/journal.pone.0056103 DB - PRIME DP - Unbound Medicine ER -