Algal pigment concentrations in meltponds and leads during the Arctic MOSAiC-expedition (Leg 4 and 5).

Algal pigment concentrations were retrieved from meltponds and leads, during Leg 4 and 5 of the MOSAiC expedition (Multidisciplinary drifting Observatory for the Study of Arctic Climate) in 2020. The summer increase in meltpond area and open lead water in the Arctic associated with increased light availability is of specific significance for biological production within the Arctic system (Smith et al. 2023). Over a period of 3.5 months, 46 samples have been collected and analysed. After extraction in 90 % acetone, samples were analysed using high-performance liquid chromatography (HPLC) on a Waters system. Algal pigments contain a multiple set of information. Firstly, pigment concentrations can show the presence of algal biomass in the various water masses sampled. Secondly, marker pigments can reveal seasonal and temporal dynamics in algal community structure, by discerning specific algal classes like diatoms, cryptophytes, haptophytes and chlorophytes that have specific roles in biogeochemical cycles. Thirdly, certain pigments are indicative of the (photo)-physiological state of micro-algae and fourth, degradation products of the main chlorophyll a pigment further give an indication about senescence and grazing in the various habitats.