Seawater browning alters community composition and reduces nutritional quality of plankton in a subarctic marine ecosystem

Inflows of coloured terrestrial organic matter cause seawater browning and reduced phytoplankton production in subarctic coastal ecosystems, potentially deteriorating the nutritional quality marine food webs. We analyzed fatty-acid (FA) compositions seston zooplankton taxa Eurytemora affinis cladocerans at three locations northern Baltic Sea. At northerly locations, salinity phosphorus concentrations were low, while humic substances (i.e., matter) high. The southerly location showed opposite trend. ratio between alga-specific ?3 polyunsaturated FA terrigenous monounsaturated (MUFA) decreased from south to north, as did docosahexaenoic acid (DHA) MUFA cladocerans. With increasing substances, biomass DHA-rich content increased. Our results indicate that alters composition, consequently affecting quality.