Cross talk: two way allelopathic interactions between toxic Microcystis and Daphnia.

Savic, Gorenka Bojadzija; Bormans, Myriam; Edwards, Christine; Lawton, Linda; Briand, Enora; Wiegand, Claudia

Abstract

Due to eutrophication, freshwater ecosystems frequently experience cyanobacterial blooms, many of which produce bioactive metabolites that can affect vertebrates and invertebrates life traits. Zooplankton are able to develop tolerance as a physiological response to cyanobacteria and their bioactive compounds, however, this comes with energetic cost that in turn influence Daphnia life traits and may impair populations. Vice versa, it has been suggested that Daphnia are able to reduce cyanobacterial dominance until a certain cyanobacterial density; it remains unclear whether Daphnia metabolites alone influence the physiological state and bioactive metabolites production of cyanobacteria. Hence, this study investigates mutual physiological reactions of toxic Microcystis aeruginosa PCC7806 and Daphnia magna. We hypothesize that a) the presence of D. magna will negatively affect growth, increase stress response and metabolites production in M. aeruginosa PCC7806 and b) the presence of M. aeruginosa PCC7806 will negatively affect physiological responses and life traits in D. magna. In order to test these hypotheses experiments were conducted in a specially designed co-culture chamber that allows exchange of the metabolites without direct contact. A clear mutual impact was evidenced. Cyanobacterial metabolites reduced survival of D.magna and decreased oxidative stress enzyme activity. Simultaneously, presence of D.magna did not affect photosynthetic activity. However, ROS increase and tendencies in cell density decrease were observed on the same day, suggesting possible energy allocation towards anti-oxidative stress enzymes, or other protection mechanisms against Daphnia infochemicals, as the strain managed to recover. Elevated concentration of intracellular and overall extracellular microcystin MC-LR, as well as intracellular concentrations of aerucyclamide A and D in the presence of Daphnia, indicating a potential protective or anti-grazing function. However, more research is needed to confirm these findings.

Citation

SAVIC, G.B., BORMANS, M., EDWARDS, C., LAWTON, L., BRIAND, E. and WIEGAND, C. 2020. Cross talk: two way allelopathic interactions between toxic Microcystis and Daphnia. Harmful algae [online], 94, article ID 101803. Available from: https://doi.org/10.1016/j.hal.2020.101803

• Journal Article Type: Article
• Acceptance Date: Apr 2, 2020
• Online Publication Date: Apr 25, 2020
• Publication Date: Apr 30, 2020
• Deposit Date: Apr 27, 2020
• Publicly Available Date: Apr 26, 2021
• Journal: Harmful algae
• Print ISSN: 1568-9883
• Electronic ISSN: 1878-1470
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 94
• Article Number: 101803
• DOI: https://doi.org/10.1016/j.hal.2020.101803
• Keywords: Zooplankton: Cyanobacteria; Secondary metabolites; PCC7806; Toxic; Oxidative stress
• Public URL: https://rgu-repository.worktribe.com/output/903320