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

Sublethal exposure to Microcystis aeruginosa extracts during the yolk-sac larval stage reduces aerobic swimming speed in juvenile zebrafish

“…All trials were performed in two independent replicates. Following a 42-h exposure period, first-feeding larvae were reared up to the metamorphosis stage (22 dpf, ca 12–13 mm total length) in clean water, following the methodology of Sergi et al ( 2022 ). In brief, larvae were reared into cubic net pens of 4.5 L volume each (0.1 mm mesh size), at 28.0 °C (± 0.5 °C), 86–95% oxygen saturation, 14/10 h light–dark photoperiod, 520–620 μS cm −1 conductivity, and 7.1–7.6 pH.…”

“…The selection of the tested extract concentration was based on the results of previous studies showing that 200 mg dw L −1 is the higher level that does not affect the survival rate of zebrafish embryos (Sergi et al 2022 ). To test whether the selected level was not lethal for the early larval stage too, preliminary duplicated trials were performed by subjecting zebrafish yolk-sac larvae (54–96 hpf) to five extract concentrations (0, 50, 100, 200, 400 mg dw L −1 ).…”

“…Cell-free crude MA extracts of lyophilized mass of M. aeruginosa (PCC 7806) culture were prepared as described in Sergi et al ( 2022 ). Lyophilised MA mass was diluted in nanopure water and submitted to ultrasonic treatment on ice.…”

“…Following our recent work on the prolonged effects of MA on zebrafish (Sergi et al 2022 ), here, we hypothesized that exposure to sublethal levels of MA during the yolk-sac larval stage (from hatching to swimbladder inflation, 54–96 hpf) could also induce long-lasting effects in the swimming performance and anatomy (ventricular shape, skeleton abnormalities) of zebrafish juveniles.…”

“…At sublethal exposure levels, MA extracts may have less severe but persistent effects on developing fish. Sergi et al ( 2022 ) demonstrated that exposure of zebrafish embryos (up to hatching, 48 h post-fertilization, hpf) to MA extracts resulted in decreased swimming performance, rounder heart ventricles, and elevated rates of vertebral abnormalities at later developmental stages.…”