Title: Allelochemical mediation of tritrophic interactions
Abstract:
Competitive interactions between cyanobacteria and macrophytes can alter the quality and quantity of both players through allelochemicals. Microcystin, a ubiquitous cyanotoxin, is known to suppress macrophyte growth. However, it is unknown how the presence of cyanotoxin alters additional interactions in the community. Such tritrophic interactions could lead to lowered ecosystem stability and potential eco-evolutionary dynamics. We tested the impact of microcystin concentration on macrophyte herbivory using duckweed (Spirodela polyrhiza), small, floating macrophytes frequently used in bioremediation, and the water lily aphid (Rhopalosiphum nymphaeae). Duckweed growth was determined by microcystin concentration (GLM, p << 0.05) though microcystin stress did not alter top-down herbivory pressure (GLM, p = 0.89). Despite the lack of increase in herbivory impact on duckweeds, herbivore populations achieved higher final populations when duckweeds were stressed by microcystin through both the changes in duckweed populations and their interaction with microcystin concentration (GLM, p << 0.05). Our results demonstrate that cyanotoxins may have far-reaching impacts in their community beyond players in which they engage in reciprocal interactions. Future work will explore how selection pressures may be exerted by the toxin amongst all three players in the tritrophic interaction, including the introduction of toxigenic and nontoxigenic ecotypes of cyanobacteria. Results will demonstrate the importance of evolutionarily informed management of cyanobacteria blooms.
Turcotte Lab
Wednesday, February 28th, 2024
12:00PM
Langley A219B