Pigment content analysis in two HAB forming dinoflagellate species during the growth period

Dinoflagellates form a large group of microalgae that have different pigments and the pigment content can vary depending on environmental conditions such as temperature, salinity, and their growth phase. They have the potential to cause red tides in coastal waters, so it is important to identify their pigments. In this study, two bloom forming dinoflagellate species, Scrippsiella trochoidea and Gyrodinium instriatum from the Oman Sea, were studied for their pigment content by HPLC every 5 days over a 30-day growth period. In both species, 10 pigment types were identified: unknown carotenoids, chlorophyll (chl) c 2 , peridinin, peridinin-like, diadinochrome, diadinoxanthin, dinoxanthin, diatoxanthin, chl a , and β,β-carotene. Although both species have the same pigment types, they vary in concentration in different days of growth. The highest cell density in S. trochoidea species was on day 15 of the growth period and the predominant pigments were chl c 2 , diadinoxanthin, and chl a . Peridinin, peridinin-like, diadinochrome, and β,β-carotene were predominant pigments on day 10, before the cell reached its maximum density. In G. instriatum , the highest cell density during the growth period was in day 10. The highest levels of unknown carotenoids, chl c 2 , diadinoxanthin, dinoxanthin, peridinin, peridinin-like, diadinochrome, and β,β-carotene pigments were measured on day 25 of growth. The type of chloroplast in both species was the peridinin type. In interpreting the pigment concentration and type, the age of the species should be considered.