Title: Quantification of microcystin production and biodegradation rates in the western basin of Lake Erie

Abstract

Abstract Cyanobacterial biomass forecasts currently cannot predict the concentrations of microcystin, one of the most ubiquitous cyanotoxins that threaten human and wildlife health globally. Mechanistic insights into how microcystin production and biodegradation by heterotrophic bacteria change spatially and throughout the bloom season can aid in toxin concentration forecasts. We quantified microcystin production and biodegradation during two growth seasons in two western Lake Erie sites with different physicochemical properties commonly plagued by summer Microcystis blooms. Microcystin production rates were greater with elevated nutrients than under ambient conditions and were highest nearshore during the initial phases of the bloom, and production rates were lower in later bloom phases. We examined biodegradation rates of the most common and toxic microcystin by adding extracellular stable isotope‐labeled microcystin‐LR (1  μ g L ⁻¹ ), which remained stable in the abiotic treatment (without bacteria) with minimal adsorption onto sediment, but strongly decreased in all unaltered biotic treatments, suggesting biodegradation. Greatest biodegradation rates (highest of −8.76 d ⁻¹ , equivalent to the removal of 99.98% in 18 h) were observed during peak bloom conditions, while lower rates were observed with lower cyanobacteria biomass. Cell‐specific nitrogen incorporation from microcystin‐LR by nanoscale imaging mass spectrometry showed that a small percentage of themore » heterotrophic bacterial community actively degraded microcystin‐LR. Microcystin production and biodegradation rates, combined with the microcystin incorporation by single cells, suggest that microcystin predictive models could be improved by incorporating toxin production and biodegradation rates, which are influenced by cyanobacterial bloom stage (early vs. late bloom), nutrient availability, and bacterial community composition.« less

Authors:

Chaffin, Justin D.  ^[1];

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Westrick, Judy A. ^[2]; Furr, Elliot ^[3]; Birbeck, Johnna A. ^[2]; Reitz, Laura A. ^[3]; Stanislawczyk, Keara ^[1]; Li, Wei ^[4]; Weber, Peter K. ^[4]; Bridgeman, Thomas B. ^[5]; Davis, Timothy W. ^[3]; Mayali, Xavier ^[4]

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+ Show Author Affiliations

1. F.T. Stone Laboratory and Ohio Sea Grant The Ohio State University Put‐In‐Bay Ohio USA
2. Lumigen Instrument Center Wayne State University Detroit Michigan USA
3. Department of Biological Sciences Bowling Green State University Bowling Green Ohio USA
4. Physical and Life Sciences Directorate Lawrence Livermore National Laboratory Livermore California USA
5. Lake Erie Center University of Toledo Oregon Ohio USA

Publication Date:

Wed May 04 00:00:00 EDT 2022

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1866304

Alternate Identifier(s):

OSTI ID: 1874111; OSTI ID: 1875319

Report Number(s):

LLNL-JRNL-827378
Journal ID: ISSN 0024-3590

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Published Article

Journal Name:

Limnology and Oceanography

Additional Journal Information:

Journal Name: Limnology and Oceanography Journal Volume: 67 Journal Issue: 7; Journal ID: ISSN 0024-3590

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Cyanobacteria; Eutrophication; Microcystis; Microcystin-LR; NanoSIMS