A UV ABSORBING COMPOUND IN HPLC PIGMENT CHROMATOGRAMS OBTAINED FROM ICELANDIC BASIN PHYTOPLANKTON

A UV absorbing compound was observed in surface waters of the Iceland Basin during the decline of a phytoplankton bloom in June 1989. The co mpound elutes early during reverse-phase HPLC analyses of phytoplankto n chlorophylls and carotenoids and has a broad absorption band from 30 0 to 470 nm with an absorption maximum at 380 nm. The compound (subseq uently referred to as P380) is characterised by similar, but not ident ical, elution properties and absorption spectrum to scytonemin, an ult raviolet sunscreen pigment not previously found in the phytoplankton. The similarity of P380 to mycosporine-like amino acids (MAAs) is also discussed. P380 concentrations are highest in surface waters, decline sharply within the upper euphotic zone, and are linearly correlated (r (2) = 0.68) with the photoprotective carotenoid diadinoxanthin.