Termination of a toxic Alexandrium bloom with hydrogen peroxide.

The dinoflagellate Alexandrium ostenfeldii is a well-known harmful algal species that can potentially cause paralytic shellfish poisoning (PSP). Usually A. ostenfeldii occurs in low background concentrations only, but in August of 2012 an exceptionally dense bloom of more than 1millioncellsL occurred in the brackish Ouwerkerkse Kreek in The Netherlands.