Amino acid and carbohydrate patterns across Fram Strait during POLARSTERN cruise PS107

Amino acids (AA) and carbohydrates (CHO) are produced by phytoplankton as part of the particulate organic carbon (POC) fraction, and can subsequently be released into the dissolved organic carbon (DOC) pool serving as food for heterotrophs. We investigated changes in quantity and quality of POC and DOC, individual AA and individual CHO across Fram Strait in summer 2017. We evaluate the organic matter processing and show that AA and CHO composition substantially differs between the particulate and dissolved fractions. The particulate fraction was enriched in essential AA and the CHO galactose, xylose/mannose, and muramic acid. In the dissolved fraction non-essential AA, several neutral CHO, and acidic and amino CHO were enriched. Our results are important for the future when changing conditions in the Central Arctic Ocean (Atlantification, warming, decreasing ice concentrations) may increase primary production and consequently degradation. The AA and CHO signatures left behind could be used as tracers after the fact to infer changes in microbial loop processes and food web interactions.