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Abstract Detail


Rzodkiewicz, Lacey [1], Turcotte, Martin [1].

Beyond the abiotic: Elucidating the importance of species interactions in harmful cyanobacteria blooms.

Harmful cyanobacteria blooms pose significant risk to human health as well as ecosystem stability through the production of cyanotoxins.   Production of cyanotoxins and bloom formation in general has previously been characterized through associations with abiotic factors.   However, few have addressed how species interactions may be responsible for 1) the evolution of toxigenicity within a bloom and 2) the ecology of the bloom.   Cyanotoxins are known to act allelopathically on other phytoplankton and macrophytes though the role of cyanotoxins in suppressing herbivory has also been observed.   Therefore, either interaction may be key to understanding how cyanobacteria blooms form.   We used a manipulative outdoor mesocosm study to address how competition by chlorophytes and floating macrophytes (duckweed species) and predation by zooplankton may influence bloom formation.   Cyanobacteria populations composed of equal densities of toxigenic and nontoxigenic genotypes of Microcystis aeruginosa were chosen due to robust quantitative PCR methodology in determining the change in the frequency of toxigenic genes within the population.   All relevant combinations of competitors, predators, and cyanobacteria in addition to monoculture controls were allowed to grow for a total of eight weeks from July through early September. Throughout the duration of the study, we censused population sizes weekly in addition to taking water samples to analyze cyanotoxin content in the water and perform qPCR to determine evolutionary change in cyanobacterial populations.   Current analysis indicates that predation may be a stronger driving force in bloom ecology (population size) than competition though analysis of bloom evolution is ongoing.   Describing the importance of species interactions in cyanobacteria bloom formation may be key to evolutionarily informed management beyond control of abiotic factors.   Additionally, this system provides insights into the role of species interactions in the evolution of toxigenicity when chemical defense varies intraspecifically.   Such insights may allow greater understanding of invasive plant species with toxins known to similarly act as an herbivory.

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1 - University of Pittsburgh, Biological Sciences, 4249 Fifth Avenue, Clapp Hall, 203, Pittsburgh, Pa, 15260, United States


Presentation Type: Oral Paper
Session: ECO2, Ecology: Invasion Biology
Location: /
Date: Tuesday, July 20th, 2021
Time: 1:45 PM(EDT)
Number: ECO2006
Abstract ID:783
Candidate for Awards:None

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