Developmental toxicity of Oscillatoria 48−3 extracts. All embryos shown (A–E) are 1 dpf. Within 1 dpf, zebrafish embryos exposed at 4- to 32-cell stage to chloroform extracts (20 μg/mL) of Oscillatoria 48−3 (A–C) arrest development at mid-blastula transition (MBT; A), or are slow to progress to gastrulation (B), compared to control embryos treated with solvent only (E). In some cases, embryos develop beyond gastrulation (C), but are notably slowed compared embryos treated at the same time with solvent only (E). Embryos treated at MBT (D) developed normally as solvent controls (E).