Fungal parasites of microalgae are crucial yet often overlooked in aquatic food webs, as they influence microbial interactions, accelerate nutrient transfer and control host population dynamics. In the rapidly warming Arctic, increased glacier meltwater significantly impacts coastal microphytobenthic communities. Dominated by benthic diatoms, which are preferential hosts for fungal parasites, these communities represent a key component in the functioning of Arctic trophic food webs. In this project, we conducted amplicon sequencing of sediment samples from different locations around Kongsfjorden (Svalbard, Norway), collected along a salinity gradient between August and September 2022.