Algal pigments in Hornsund (Svalbard) sediments as biomarkers of Arctic productivity and environmental conditions

Abstract

Pigments (chloropigments-a and carotenoids) in sediments and macroalgae samples, collected in Hornsund, in July 2015 and July 2016, were analysed (HPLC) in this work. In spite of the aerobic conditions and the periodic intensive solar irradiation in the Arctic environment, neither of which favour pigment preservation in water column and surface sediments, our results indicate that these compounds can provide information about phytoplankton composition, primary production and environmental conditions in this region. The sum of chloropigments-a, a marker of primary production, in the Hornsund sediments varied from 0.40 to 14.97 nmol/g d.w., while the sum of carotenoids ranged from 0.58 to 8.08 nmol/g d.w. Pheophorbides-a and pyropheophorbides-a made up the highest percentage in the sum of chloropigments-a in these sediments, supplying evidence for intensive zooplankton and/or zoobenthos grazing. Among the carotenoids, fucoxanthin and its derivatives (19'-hexanoyloxyfucoxanthin and 19'-hexanoyloxy-4-ketofucoxanthin) contributed the highest percentage, which points to the occurrence mainly of diatoms and/or haptophytes in the water. The pigment markers show that the input of macroalgae to the total biomass could be considerable only in the intertidal zone.