Sublethal exposure to Microcystis aeruginosa extracts during embryonic development reduces aerobic swimming capacity in juvenile zebrafish

• Published in: Aquatic toxicology Vol. 243; p. 106074
• Main Authors: Sergi, Emmanolia, Orfanakis, Michail, Dimitriadi, Anastasia, Christou, Maria, Zachopoulou, Anthi, Kourkouta, Chara, Printzi, Alice, Zervou, Sevasti-Kiriaki, Makridis, Pavlos, Hiskia, Anastasia, Koumoundouros, George
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-02-2022
• Subjects: Animals; Critical swimming speed; Ecosystem; Embryo; Embryonic Development; Heart; Microcystins; Microcystis; Skeleton; Swimming; Water Pollutants, Chemical - toxicity; Zebrafish; Heart; Zebrafish; Embryo; Critical swimming speed; Skeleton; Microcystis
• DOI: 10.1016/j.aquatox.2022.106074
• EISSN: 1879-1514
• ISSN: 0166-445X

•The long-term effect of sublethal exposure to Microcystis aeruginosa extracts during the embryonic stage of zebrafish was examined.•Pre-exposed larvae at metamorphosis showed a significant reduction in swimming performance (RUcrit).•Pre-exposed fish also presented rounder cardiac ventricles and a high vertebral abnormalities rate.
In the last decades, cyanobacterial harmful algal blooms (CyanoHABs) pose an intensifying ecological threat. Microcystis aeruginosa is a common CyanoHAB species in freshwater ecosystems, with severe toxic effects in a wide range of organisms. In the present paper we examined whether transient and short (48 h) exposure of fish embryos to sublethal levels of M. aeruginosa crude extract (200 mg biomass dw L−1) affects swimming performance at later life stages (end of metamorphosis, ca 12 mm TL, 22,23 days post-fertilization). Pre-exposed metamorphosing larvae presented a significant decrease in swimming performance (9.7 ± 1.6 vs 11.4 ± 1.7 TL s−1 in the control group, p < 0.01), and a significant decrease in the ventricle length-to-depth ratio (1.23 ± 0.15 vs 1.42 ± 0.15 in control fish, p < 0.05). In addition, extract-exposed fish presented significantly elevated rates of vertebral abnormalities (82 ± 13% vs 7 ± 4% in the control group), mainly consisting of the presence of extra neural and haemal processes. No significant differences between groups were detected in survival and growth rates. Results are discussed in respect to the mechanisms that might mediate the detected cyanobacterial effects. This is the first evidence of a direct link between sublethal exposure to M. aeruginosa during the embryonic period and swimming performance at later life-stages. Decreased swimming performance, altered cardiac shape, and elevated vertebral abnormalities in response to early exposure to M. aeruginosa could have significant effects on fish populations in the wild.