PYROPHAEOPORPHYRINS C(1) AND C(2) - GRAZING PRODUCTS OF CHLOROPHYLL-CIN AQUATIC ENVIRONMENTS

Pyrophaeoporphyrins c(1) and c(2) (I a, b), transformation products of chlorophylls c(1) and c(2) (II a, b) occur as minor pigments in the s urface sediment (0-5 cm) of Priest Pot, a small eutrophic lake (Cumbri a, U.K.) and in the products from feeding the diatom Thalassiosira wei ssflogii to the copepod Calanus helgolandicus. These findings, based o n comparisons with standards prepared from the chlorophylls c(1) and c (2), indicate that enzymatic removal of the C-13(2) carbomethoxy subst ituent, a prerequisite for the diagenetic transformation pathway of th e chlorophylls c to a number of sedimentary alkyl porphyrins, occurs m ainly in the water column as a result of zooplankton herbivory. (C) 19 98 Elsevier Science Ltd. All rights reserved.