Type I and Type II chlorophyll-a transformation products associated with algal senescence

► Chlorophyll-a transformation was tracked during the senescence of microalgal cultures. ► Demetallated Type I chl-a transformation products were dominant in Pavlova gyrans. ► Oxidative Type I transformation products were dominant in Isochrysis galbana. ► Type I products were different in the dark and nutrient depleted senescent cultures of I. galbana. ► Novel Type I compounds were detected such as chl-d like compound and a chl-a precursor like compound.