Dynamic phytoplankton community structure in a subtropical reservoir during an extended drought, Central Texas, USA

Subtropical lakes remain understudied by comparison to lakes in temperate and tropical regions when considering environmental factors impacting cyanobacterial harmful algal bloom (CyanoHAB) propagation and success. Central Texas, USA, exhibited an extended, severe drought from 2010 to 2015. Phytopla...

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Bibliographic Details
Published in:Aquatic sciences 2023, Vol.85 (1), p.7, Article 7
Main Authors: Gámez, Tatiana E., Groeger, Alan W., Manning, Schonna R.
Format: Article
Language:English
Subjects:
Algae
Algal blooms
Analysis
Biological monitoring
Biomedical and Life Sciences
Community structure
Cyanobacteria
Deoxyribonucleic acid
Diatoms
DNA
DNA barcoding
DNA sequences
DNA sequencing
Drought
Droughts
Ecology
Environmental factors
Environmental impact
Environmental Management
Eutrophic environments
Eutrophication
Freshwater & Marine Ecology
Lakes
Life Sciences
Marine & Freshwater Sciences
Marine microorganisms
Nucleotide sequencing
Nutrient loading
Nutrients
Oceanography
Parameter identification
Phytoplankton
Planktothrix
Research Article
Reservoirs
Sequence analysis
Success
Trophic levels
Trophic status
Trophic structure
Tropical environment
Tropical environments
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Summary:Subtropical lakes remain understudied by comparison to lakes in temperate and tropical regions when considering environmental factors impacting cyanobacterial harmful algal bloom (CyanoHAB) propagation and success. Central Texas, USA, exhibited an extended, severe drought from 2010 to 2015. Phytoplankton data from Lake Buchanan, a large reservoir on the Colorado River, displayed rapid shifts in the community during this period as the reservoir transitioned to more eutrophic conditions. This study serves to assess the likelihood of CyanoHABs considering this recent transition in trophic status and determine factors promoting success of potentially harmful species. Routine monitoring was performed every other month, including measurements of environmental parameters, nutrients, as well as the identification of phytoplankton using DNA barcoding and cell counts. DNA sequencing analysis confirmed the presence of multiple known bloom-forming cyanobacteria. Potential producers of saxitoxins Planktothrix , Aphanizomenon / Chrysosporum , and Raphidiopsis thrived in drought conditions, whereas Limnothrix and Pseudanabaena performed better during non-drought conditions. Following the drought period, Chrysosporum ovalisporum , Phormidium tenue , and Planktothrix sp. were still present along with other potentially harmful species; however, the community had shifted to predominantly diatoms comprised of Fragilaria and Lindavia . These results suggest the drought conditions, i.e., increased conductivity, temperature, and nutrient loads, likely influenced the success of potentially toxic cyanobacteria. The success of these taxa contributed to eutrophication and subsequent decline in diversity. Subtropical lakes should therefore be monitored more closely during extended drought periods, as the risks associated with eutrophication and CyanoHABs are predicted to be significantly higher.
ISSN:1015-1621
1420-9055
DOI:10.1007/s00027-022-00903-1