UNDER EMBARGO - This dataset is part of BE/2023 sampling campagn in SW Greenland fjords (Igaliku and Tunulliarfik). The dataset reports the final concentrations (μg L⁻¹) of each detected photosynthetic pigment, used to infer phytoplankton functional groups and compare community composition across fjords with differing glacial influence and between seasons (spring–summer). For pigment analysis, seawater volumes ranging from 700 mL to 1 L were filtered onto 25-mm diameter Whatman GF/F filters and immediately stored at -80°C until further analysis. Pigments were extracted using 90% acetone and analysed by High-Performance Liquid Chromatography (HPLC) following the method of Van Heukelem and Thomas (2001). Calibration was performed using pigment standards from DHI Water and Environment (Hørsholm, Denmark). In the dataset is indicated the final consentration (μg/L) of each detected photosyntetic pigment.

UNDER EMBARGO - This dataset contains marine organic matter source samples, artificial mixtures of known composition, and compound-specific nitrogen stable isotope data of amino acids (δ¹⁵N-AA). Source materials include phytoplankton, zooplankton, and faecal pellets from the marine fouling species Mytilus edulis and Metridium senile.Samples were collected and processed in the laboratory under controlled conditions. Artificial mixtures were prepared by combining source materials in defined proportions to generate experimental samples representing multiple marine organic matter source combinations. Metadata describing sample collection, preparation, and mixture composition are included.Compound-specific nitrogen isotope ratios of individual amino acids were measured using stable isotope analysis. The dataset includes isotopic measurements for all source samples and artificial mixtures, along with associated metadata required to document sampling, laboratory preparation, and analytical procedures.