A harmonised dataset of field observations on zoosporic parasites infecting aquatic primary producers

Zoosporic parasites are a polyphyletic group of microorganisms characterised by a motile spore stage, which play a crucial ecological role in aquatic environments. They are known to influence population dynamics of aquatic primary producers, nutrient cycling, and energy transfer within microbial food webs. Despite their importance, data on their diversity, distribution, and interactions with their hosts remain sparse and fragmented. Here, we present a harmonised dataset of field observations on zoosporic parasites infecting aquatic primary producers. The dataset integrates both published and previously unpublished records, encompassing more than 4,427 observations collected between 2007 and 2021 across 28 sites in Europe and North America. It includes data for 91 unique parasite taxa, along with confirmed and putative parasite–host associations derived from direct microscopic or molecular evidence. All records were standardised using the Darwin Core schema to ensure interoperability and long-term usability. This open-access resource provides a foundation for comparative and meta-analytical studies on parasite–host ecology, biodiversity assessments, and industrial applications related to algal production systems.