Complex sentence: Microcystins are cyclic nonribosomal peptides produced in large quantities during algae blooms by the bacteria genus microcystis or planktothrix cyanobacteria (i.e. the species "Microcystis aeruginosa"), blooms are often called blue-green algae, depending on their appearance.
Split into simpler sentences: Microcystins are cyclic nonribosomal peptides produced in large quantities during algae blooms by the bacteria genus microcystis or planktothrix cyanobacteria (i.e. the species "Microcystis aeruginosa"). Cyanobacteria blooms are often called blue-green algae bloom, depending on their appearance.