POTENTIAL OF SOME CAROTENOIDS IN 2 RECENT SEDIMENTS OF KIEL BIGHT AS BIOGENIC INDICATORS OF PHYTODETRITUS

Carotenoids are routinely used as biogenic markers for plant debris in the marine environment. But, like the chlorophylls, carotenoids suffer chemical alteration and even hydrolysation to colourless endproducts when detritus is metabolized by animals and bacteria in the water column. This study investigates the stability of pigments after deposition in surface sediments. In a laboratory experiment using oxic sediment, the carotenoid lutein exhibited greater stability against chemical and microbial breakdown than chlorophyll a, which has a half-life of only 3 wk under oxic conditions. In situ investigations in anoxic mud sediments in Kiel Bight, Germany, showed rapid disintegration of polar xanthophylls and chloropigments. beta-Carotene and lutein were relatively stable in anoxic sediment. Data from a 1 yr field study at 2 stations in Kiel Bight are reported as an example of the applicability of carotenoid pigments as biogenic markers in sediments. Advective transport of macrophyte debris was investigated by measuring the concentration of lutein in different sediments on a down-slope transect. Lutein exhibited a pattern of slowly increasing red macrophyte input to the muddy sediments, starting in autumn and continuing through winter; but it was not detected in shallow sand sediments near the growth sites of the algae. Fucoxanthin and peridinin were found in both muddy and sandy sediment, reflecting sedimentation events resulting from transport of phytoplankton from the water column.