Document Type
Article
Author ORCID Identifier
Gabriella M. Lawson https://orcid.org/0000-0001-6018-2692
Jakob L. Young https://orcid.org/0009-0008-8266-5810
Erin F. Jones https://orcid.org/0000-0002-9999-1021
Michelle A. Baker https://orcid.org/0000-0002-7188-8639
Hans W. Paerl https://orcid.org/0000-0003-2211-1011
Greg Carling https://orcid.org/0000-0001-5820-125X
Raymond Lee https://orcid.org/0000-0003-4625-9707
Rachel L. Wood https://orcid.org/0000-0001-7953-3173
Journal/Book Title/Conference
Harmful Algae
Volume
143
Publisher
Elsevier BV
Publication Date
2-14-2025
Journal Article Version
Version of Record
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
First Page
1
Last Page
14
Abstract
Though freshwater harmful algal blooms have been described and studied for decades, several important dynamics remain uncertain, including the relationships among nutrient concentrations, phytoplankton growth, and cyanotoxin production. To identify when and where nutrients limit phytoplankton, cyanobacteria, and cyanotoxins, we conducted in situ bioassay studies. We added nitrogen (N), phosphorus (P), or N + P across various seasons in water collected from three locations across Utah Lake, one of the largest freshwater lakes in the western U.S. This shallow, hypereutrophic lake provides a powerful testbed for quantifying nutrient-growthtoxin interactions. We assessed a range of parameters over time, including photopigment concentrations, phytoplankton abundance (cell counts), cyanotoxins, and nutrient concentrations. Despite high background nutrient concentrations in lake water, phytoplankton abundance and composition were strongly affected by nutrient addition. Phosphorus limitation was more common in the spring, with N limitation and N + P limitation becoming more common in the fall. Nutrient additions were positively associated with cyanobacteria (Microcystis, Aphanocapsa, Dolichospermum, Merismopedia, Aphanizomenon spp.), eukaryotes (Aulacoseira, Desmodesmus spp.), and two taxonomical categories of phytoplankton (i.e., unicellular and colonial green algae). When detected, anatoxin-a was positively associated with Aphanizomenon and negatively associated with Microcystis spp. However, overall cyanotoxin concentrations were not associated with cyanobacterial cell density but varied seasonally. These findings highlight the importance of considering seasonal nutrient availability dynamics and provide insights into specific nutrient targets, species, and cyanotoxins that play a significant role in the health and management of similar eutrophic lake environments around the world.
Recommended Citation
Lawson, G.M., Young, J.L., Aanderud, Z.T., et al. Nutrient limitation and seasonality associated with phytoplankton communities and cyanotoxin production in a large, hypereutrophic lake. Harmful Algae 2025 143 https://doi.org/10.1016/j.hal.2025.102809